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Sample records for palapa b2r satellite

  1. Modeling And Simulation Of Prolate Dual-Spin Satellite Dynamics In An Inclined Elliptical Orbit: Case Study Of Palapa B2R Satellite

    CERN Preprints

    Muliadi, J; Budiyono, A

    2008-01-01

    In response to the interest to re-use Palapa B2R satellite nearing its End of Life (EOL) time, an idea to incline the satellite orbit in order to cover a new region has emerged in the recent years. As a prolate dual-spin vehicle, Palapa B2R has to be stabilized against its internal energy dissipation effect. This work is focused on analyzing the dynamics of the reusable satellite in its inclined orbit. The study discusses in particular the stability of the prolate dual-spin satellite under the effect of perturbed field of gravitation due to the inclination of its elliptical orbit. Palapa B2R physical data was substituted into the dual-spin's equation of motion. The coefficient of zonal harmonics J2 was induced into the gravity-gradient moment term that affects the satellite attitude. The satellite's motion and attitude were then simulated in the perturbed gravitational field by J2, with the variation of orbit's eccentricity and inclination. The analysis of the satellite dynamics and its stability was conducte...

  2. Equalizers for communications satellites

    MIT - DSpace

    Fay, Leon

    2008-01-01

    This thesis investigates equalization for advanced protected satellite communications systems in development at MIT Lincoln Laboratory. Equalizers facilitate high data rate communication by correcting dispersion in the ...

  3. Satellite communication systems

    CERN Preprints

    Evans, BG

    1999-01-01

    The book is very clear and comprehensive. The scope of the book is very large: almost all aspects of current satellite communication systems are studied. Hence, the book keeps its promise in that it provides a quick start for someone who is new to the satellite communications business.

  4. Optimization of Satellite Constellation Reconfiguration

    Engineering Websites

    Optimization of Satellite Constellation Reconfiguration by Uriel Scialom Submitted Students #12;2 #12;Optimization of Satellite Constellation Reconfiguration by Uriel Scialom Submitted for the degree of Master of Science in Aeronautics and Astronautics Abstract Traditional satellite constellation

  5. Experimental Satellite Quantum Communications

    Quantum Physics (arXiv)

    Giuseppe Vallone; Davide Bacco; Daniele Dequal; Simone Gaiarin; Vincenza Luceri; Giuseppe Bianco; Paolo Villoresi

    2014-06-16

    Quantum Communications on planetary scale require complementary channels including ground and satellite links. The former have progressed up to commercial stage using fiber-cables, while for satellite links, the absence of terminals in orbit has impaired theirs development. However, the demonstration of the feasibility of such links is crucial for designing space payloads and to eventually enable the realization of protocols such as quantum-key-distribution (QKD) and quantum teleportation along satellite-to-ground or intersatellite links. We demonstrated the faithful transmission of qubits from space to ground by exploiting satellite corner cube retroreflectors acting as transmitter in orbit, obtaining a low error rate suitable for QKD. We also propose a two-way QKD protocol exploiting modulated retroreflectors that necessitates a minimal payload on satellite, thus facilitating the expansion of Space Quantum Communications.

  6. Satellite Products and Services Review Board ATBD: Satellite-Derived

    Environmental Sciences and Ecology Websites

    Miami, University of

    Satellite Products and Services Review Board ATBD: Satellite-Derived Ocean Heat Content Version 1.0 July 2012 ___________________________________ #12;NOAA /RSMAS ATBD : Satellite-Derived Ocean Heat/STAR) #12;NOAA /RSMAS ATBD : Satellite-Derived Ocean Heat Content Product Page 3 of 32 TABLE OF CONTENTS

  7. Destriping Satellite Images

    MIT - DSpace

    Horn, B.K.P.

    1978-03-01

    Before satellite images obtained with multiple image sensors can be used in image analysis, corrections must be introduced for the differences in transfer functions on these sensors. Methods are here presented for ...

  8. REZA RABIEI, PhD 2444 Benny Crescent ~ Montreal, Quebec H4B 2R3

    Engineering Websites

    Barthelat, Francois

    (advisor), Pascal Hubert, Rosaire Mongrain M.Sc., Mechanical Engineering Sep. 2004 ­ Feb. 2007 Iran University of Science and Technology, Tehran, Iran, GPA: 3.74/4.0 Dissertation: Optimum design of composite Engineering Sep. 2000 ­ Sep. 2004 Tehran Polytechnic, Tehran, Iran, GPA: 3.63/4.0 Dissertation: Mechanical

  9. Marine Gravity from Satellite Altimetry

    Geosciences Websites

    Sandwell, David T.

    Marine Gravity from Satellite Altimetry Geodynamics, November, 2014 · basic theory · retracking altimeter waveforms and CryoSat · gravity from satellite altimetry · predicting bathymetry from gravity #12 that of CHAMP, GRACE, and GOCE #12;Marine Gravity from Satellite Altimetry · basic theory · gravity from

  10. Dynamical friction on satellite galaxies

    Astrophysics (arXiv)

    Michiko Fujii; Yoko Funato; Junichiro Makino

    2006-06-23

    For a rigid model satellite, Chandrasekhar's dynamical friction formula describes the orbital evolution quite accurately, when the Coulomb logarithm is chosen appropriately. However, it is not known if the orbital evolution of a real satellite with the internal degree of freedom can be described by the dynamical friction formula. We performed N-body simulation of the orbital evolution of a self-consistent satellite galaxy within a self-consistent parent galaxy. We found that the orbital decay of the simulated satellite is significantly faster than the estimate from the dynamical friction formula. The main cause of this discrepancy is that the stars stripped out of the satellite are still close to the satellite, and increase the drag force on the satellite through two mechanisms. One is the direct drag force from particles in the trailing tidal arm, a non-axisymmetric force that slows the satellite down. The other is the indirect effect that is caused by the particles remaining close to the satellite after escape. The force from them enhances the wake caused in the parent galaxy by dynamical friction, and this larger wake in turn slows the satellite down more than expected from the contribution of its bound mass. We found these two have comparable effects, and the combined effect can be as large as 20% of the total drag force on the satellite.

  11. Correspondence Satellites: make data

    Biology and Medicine Websites

    Courchamp, Franck

    from the US Landsat satellites with those from the European Space Agency's planned Sentinel-2.foody@nottingham.ac.uk *On behalf of 7 co-signatories. See go.nature.com/wu1f3e for full list. Monster fern makes IUCN go.nature.com/qa9z1g). After a position on the list fell vacant as a result of the global eradication

  12. Interferometric Observations of Geosynchronous Satellites

    CERN Preprints

    Subrahmanya, C R; Somashekar, R

    2011-01-01

    In recent years, a large number of geosynchronous satellites are being planned to provide augmentation services for enhancing the precision to global positioning systems, e.g., GPS, in applications such as aircraft landing. In this paper, we present a scheme for co-locating passive satellite observational facilities with a radio astronomy facility to open a new possibility of providing valuable data for radio astronomical imaging, ionospheric studies and satellite orbit estimation.

  13. NOAA/NMFS Developments Tracked By Satellite

    Environmental Sciences and Ecology Websites

    NOAA/NMFS Developments Sea Turtle Tracked By Satellite A satellite traditionally used to de- tect- veston, Tex., called the unusual use of the Nimbus satellite an unqualified success. "Satellite tracking near Washington, D. C. , where they were processed by com- puter. Satellite tracking of turtles

  14. On board computers for satellites

    CERN Preprints

    Perry, M A

    1972-01-01

    The paper is concerned with stored program general purpose digital computers for use on satellites. Environmental and other constraints which render satellite computers different from equivalent ground machines are discussed and several approaches to the realization of such computers are briefly illustrated where three representative architectures are described. Finally the architecture of an on board computer under development by ESRO is described. (14 refs).

  15. Theory of satellite geodesy applications of satellites to geodesy

    CERN Preprints

    Kaula, William M

    2000-01-01

    The main purpose of this classic text is to demonstrate how Newtonian gravitational theory and Euclidean geometry can be used and developed in the earth's environment. The second is to collect and explain some of the mathematical techniques developed for measuring the earth by satellite.Book chapters include discussions of the earth's gravitational field, with special emphasis on spherical harmonies and the potential of the ellipsoid; matrices and orbital geometry; elliptic motion, linear perturbations, resonance, and other aspects of satellite orbit dynamics; the geometry of satellite obser

  16. Redefining the Missing Satellites Problem

    Astrophysics (arXiv)

    Louis E. Strigari; James S. Bullock; Manoj Kaplinghat; Juerg Diemand; Michael Kuhlen; Piero Madau

    2007-10-24

    Numerical simulations of Milky-Way size Cold Dark Matter (CDM) halos predict a steeply rising mass function of small dark matter subhalos and a substructure count that greatly outnumbers the observed satellites of the Milky Way. Several proposed explanations exist, but detailed comparison between theory and observation in terms of the maximum circular velocity (Vmax) of the subhalos is hampered by the fact that Vmax for satellite halos is poorly constrained. We present comprehensive mass models for the well-known Milky Way dwarf satellites, and derive likelihood functions to show that their masses within 0.6 kpc (M_0.6) are strongly constrained by the present data. We show that the M_0.6 mass function of luminous satellite halos is flat between ~ 10^7 and 10^8 M_\\odot. We use the ``Via Lactea'' N-body simulation to show that the M_0.6 mass function of CDM subhalos is steeply rising over this range. We rule out the hypothesis that the 11 well-known satellites of the Milky Way are hosted by the 11 most massive subhalos. We show that models where the brightest satellites correspond to the earliest forming subhalos or the most massive accreted objects both reproduce the observed mass function. A similar analysis with the newly-discovered dwarf satellites will further test these scenarios and provide powerful constraints on the CDM small-scale power spectrum and warm dark matter models.

  17. The tidal stripping of satellites

    Astrophysics (arXiv)

    J. I. Read; M. I. Wilkinson; N. W. Evans; G. Gilmore; Jan T. Kleyna

    2005-11-15

    We present an improved analytic calculation for the tidal radius of satellites and test our results against N-body simulations. The tidal radius in general depends upon four factors: the potential of the host galaxy, the potential of the satellite, the orbit of the satellite and {\\it the orbit of the star within the satellite}. We demonstrate that this last point is critical and suggest using {\\it three tidal radii} to cover the range of orbits of stars within the satellite. In this way we show explicitly that prograde star orbits will be more easily stripped than radial orbits; while radial orbits are more easily stripped than retrograde ones. This result has previously been established by several authors numerically, but can now be understood analytically. For point mass, power-law (which includes the isothermal sphere), and a restricted class of split power law potentials our solution is fully analytic. For more general potentials, we provide an equation which may be rapidly solved numerically. Over short times ($\\simlt 1-2$ Gyrs $\\sim 1$ satellite orbit), we find excellent agreement between our analytic and numerical models. Over longer times, star orbits within the satellite are transformed by the tidal field of the host galaxy. In a Hubble time, this causes a convergence of the three limiting tidal radii towards the prograde stripping radius. Beyond the prograde stripping radius, the velocity dispersion will be tangentially anisotropic.

  18. Shape Alignments of Satellite Galaxies

    Astrophysics (arXiv)

    G. M. Bernstein; P. Norberg

    2002-05-29

    We test a sample of satellites of isolated primary galaxies, extracted from the 2dF Galaxy Redshift Survey (2dFGRS), for any tendency to be aligned along (or against) the primary-to-satellite radius vector. If tidal effects induce such an alignment, it would contaminate recent measurements of galaxy halo masses which use the coherent alignment induced on background galaxies by gravitational lensing. The mean tangential ellipticity of 1819 satellites within 500 kpc projected radius is = +0.004+-0.008, so no tidal alignment is detected. This implies at 95% confidence that satellite alignment is less than a 20% contamination of the alignment signal attributed to galaxy-galaxy lensing by Smith et al. (2001) and McKay et al. (2001).

  19. Transiting Exoplanet Survey Satellite (TESS)

    MIT - DSpace

    Ricker, George R.

    The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be ...

  20. Satellites of Isolated Elliptical Galaxies

    Astrophysics (arXiv)

    Rodney M. Smith; Vicent J. Martinez

    2003-09-30

    Using well-defined selection criteria applied to the LEDA galaxy catalogue we have derived a sample of elliptical galaxies that can be classified as isolated. From this we have investigated the neighbourhood of these galaxies to determine the frequency and radial distribution of faint galaxies around them and hence derive an estimate of their surrounding satellite population. The results are compared and contrasted to the satellite population around isolated spiral galaxies.

  1. Satellite Transport Protocol Handling Bit Corruption,

    Computer Technologies and Information Sciences Websites

    Barbeau, Michel

    containing low Earth orbiting (LEO) satellite links. Although wireless and satellite links certainly share protocol (STP) for satellite networks. This paper proposes a new error control strategy for STP that makesSatellite Transport Protocol Handling Bit Corruption, Handoff and Limited Connectivity MAGED E

  2. Modern Digital Satellite Television: How It Works

    Computer Technologies and Information Sciences Websites

    Valenti, Matthew C.

    Modern Digital Satellite Television: How It Works Matthew C. Valenti Lane Department of Computer #12;Outline 1 Satellite Television Standards 2 DVB-S2 Modulation 3 LDPC Coding 4 Tricks for Improving Virginia UniverLDPC Codes Nov. 7, 2011 2 / 33 #12;Satellite Television Standards Outline 1 Satellite

  3. A networking perspective on satellite constellations

    Engineering Websites

    Wood, Lloyd

    A networking perspective on satellite constellations Ecole d'Hiver des Télécommunications de Sophia networking perspective on satellite constellations - Lloyd Wood 2 We aim to build up a picture of satellite constellations and how we can simulate them as networks. To do that, we'll cover: · orbital geometry of satellite

  4. Realizing Future Broadband Satellite Network Services

    Computer Technologies and Information Sciences Websites

    Jain, Raj

    Realizing Future Broadband Satellite Network Services Sastri Kota Arjan Durresi, Raj Jain Lockheed@cis.ohio-state.edu ABSTRACT Future satellite communication systems proposed use geosynchronous (GEO) satellites, medium earth orbit (MEO), and low earth orbit (LEO) constellations. Most of the next generation satellite systems

  5. Satellite Remote Sensing SIO 135/SIO 236

    Geosciences Websites

    Sandwell, David T.

    Satellite Remote Sensing SIO 135/SIO 236 Satellite Radar and Laser Altimetry #12;SNOW (s) SEA level #12;What is the ellipsoid? #12;Altimetersatellites #12;#12;Altimeter satellite coverage #12;ERS transmitted pulse returned pulse Satellite T ·Altimeter measures the time delay (T) taken for a radar pulse

  6. Want to Install A Satellite Dish ?

    Environmental Sciences and Ecology Websites

    Maxwell, Bruce D.

    Want to Install A Satellite Dish ? Good News! Satellite dishes are allowed in Family & Graduate of units to allow for installation of satellite dishes are not permitted. If damage oc- curs to Family damage to satellite dish equipment. 3. Residents are expected to maintain the grounds/area surrounding

  7. More Satellites of Spiral Galaxies

    Astrophysics (arXiv)

    Dennis Zaritsky; Rodney Smith; Carlos Frenk; Simon D. M. White

    1996-11-24

    We present a revised and expanded catalog of satellite galaxies of a set of isolated spiral galaxies similar in luminosity to the Milky Way. This sample of 115 satellites, 69 of which were discovered in our multifiber redshift survey, is used to further probe the results obtained from the original sample (Zaritsky et al. 1993). The satellites are, by definition, at projected separations <~ 500 kpc, have absolute recessional velocity differences with respect to the parent spiral of less than 500 km/s and are at least 2.2 mag fainter than their associated primary galaxy. A key characteristic of this survey is the strict isolation of these systems, which simplifies any dynamical analysis. We find no evidence for a decrease in the velocity dispersion of the satellite system as a function of radius out to galactocentric radii of 400 kpc, suggesting that the halo extends well beyond 200 kpc. Furthermore, the new sample affirms our previous conclusions (Zaritsky et al. 1993) that (1) the velocity difference between a satellite and its primary is not strongly correlated with the rotation speed of the primary, (2) the system of satellites has a slight net rotation (34 \\pm 14 km\\s) in the same sense as the primary's disk, and (3) that the halo mass of an ~ L* spiral galaxy is in excess of 2 x 10^{12} solar masses.

  8. Characterizing switching problems in low earth orbit satellite constellations with satellite failures 

    Texas A&M University - TxSpace

    Wadsworth, Brandon Scott

    1999-01-01

    In this research, we study the ability of LEO satellite constellations to handle data traffic. LEO satellites offer a number of advantages over traditional space based communications via geosynchronous orbit satellites (GEO). However...

  9. Gaussian Entanglement Distribution via Satellite

    CERN Preprints

    Hosseinidehaj, Nedasadat

    2014-01-01

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the trade-off between space-based engineering complexity and the rate of ground-station entanglement generation...

  10. Gaussian Entanglement Distribution via Satellite

    Quantum Physics (arXiv)

    Nedasadat Hosseinidehaj; Robert Malaney

    2015-02-05

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the trade-off between space-based engineering complexity and the rate of ground-station entanglement generation.

  11. Dark Matter tested with satellites

    CERN Preprints

    Combes, F

    2009-01-01

    Recently, the distribution of velocity dispersion as far as 400kpc around red isolated galaxies was derived from statistical studies of satellites in the SDSS (Klypin & Prada 2009). This could help to constrain dark matter models at intermediate scales. We compare the predictions of different DM distributions, LCDM with NFW or cored profiles, and also modified gravity models, with observations. It is shown how the freedom in the various parameters (radial distribution of satellites, velocity anisotropy, external field effect), prevents to disentangle the models, which all can give pretty good fits to the data. In all cases, realistic radial variations of velocity anisotropy are used for the satellites, and a constant stellar-mass to light ratio for the host galaxies.

  12. Small satellites and their regulation

    CERN Preprints

    Jakhu, Ram S

    2014-01-01

    Since the launch of UoSat-1 of the University of Surrey (United Kingdom) in 1981, small satellites proved regularly to be useful, beneficial, and cost-effective tools. Typical tasks cover education and workforce development, technology demonstration, verification and validation, scientific and engineering research as well as commercial applications. Today the launch masses range over almost three orders of magnitude starting at less than a kilogram up to a few hundred kilograms, with budgets of less than US$ 100.00 and up to millions within very short timeframes of sometimes less than two years. Therefore each category of small satellites provides specific challenges in design, development and operations. Small satellites offer great potentials to gain responsive, low-cost access to space within a short timeframe for institutions, companies, regions and countries beyond the traditional big players in the space arena. For these reasons (particularly the low cost of construction, launch and operation), small (m...

  13. Chameleon gravity and satellite geodesy

    HEP - Theory (arXiv)

    J. R. Morris

    2014-09-29

    We consider the possibility of the detection of a chameleon effect by an earth orbiting satellite such as LAGEOS, and possible constraints that might be placed on chameleon model parameters. Approximate constraints presented here result from using a simple monopole approximation for the gravitational field of the earth, along with results from the Khoury-Weltman chameleon model, solar system constraints obtained from the Cassini mission, and parameter bounds obtained from the LAGEOS satellite. It is furthermore suggested that a comparison of ground-based and space-based multipole moments of the geopotential could reveal a possible chameleon effect.

  14. Chameleon gravity and satellite geodesy

    CERN Preprints

    Morris, J R

    2014-01-01

    We consider the possibility of the detection of a chameleon effect by an earth orbiting satellite such as LAGEOS, and possible constraints that might be placed on chameleon model parameters. Approximate constraints presented here result from using a simple monopole approximation for the gravitational field of the earth, along with results from the Khoury-Weltman chameleon model, solar system constraints obtained from the Cassini mission, and parameter bounds obtained from the LAGEOS satellite. It is furthermore suggested that a comparison of ground-based and space-based multipole moments of the geopotential could reveal a possible chameleon effect.

  15. Transmission scheduling for wireless and satellite systems

    MIT - DSpace

    Ganti, Anand, 1975-

    2003-01-01

    We study queuing systems with time-varying service rates, as a natural model of satellite and wireless communication systems. Packets arrive at a satellite to be transmitted to one of the sub-regions (channels) in a service ...

  16. Satellite altimeter remote sensing of ice caps 

    Edinburgh, University of - Research Archive

    Rinne, Eero Juhani

    2011-11-24

    This thesis investigates the use of satellite altimetry techniques for measuring surface elevation changes of ice caps. Two satellite altimeters, Radar Altimeter 2 (RA-2) and Geoscience Laser Altimeter System (GLAS) are ...

  17. Are rotating planes of satellite galaxies ubiquitous?

    CERN Preprints

    Phillips, John I; Bullock, James S; Boylan-Kolchin, Michael

    2015-01-01

    We compare the dynamics of satellite galaxies in the Sloan Digital Sky Survey to simple models in order to test the hypothesis that a large fraction of satellites co-rotate in coherent planes. We confirm the previously-reported excess of co-rotating satellite pairs located near diametric opposition with respect to the host, but show that this signal is unlikely to be due to rotating discs (or planes) of satellites. In particular, no overabundance of co-rotating satellites pairs is observed within $\\sim 20^{\\circ}-50^{\\circ}$ of direct opposition, as would be expected for planar distributions inclined relative to the line-of-sight. Instead, the excess co-rotation for satellite pairs within $\\sim 10^{\\circ}$ of opposition is consistent with random noise associated with undersampling of an underlying isotropic velocity distribution. We conclude that at most $10\\%$ of the hosts in our sample harbor co-rotating satellite planes (as traced by the luminous satellite population).

  18. Landsat--Earth Observation Satellites Since 1972, Landsat satellites have continuously acquired space-

    Geosciences Websites

    Landsat--Earth Observation Satellites Since 1972, Landsat satellites have continuously acquired instruments and the spacecraft, then launches and validates the performance of the instruments and satellites. The USGS then assumes ownership and operation of the satellites, in addition to managing all ground

  19. Analysis of Low Earth Orbit Satellite Networks with Inter-satellite Links

    Computer Technologies and Information Sciences Websites

    Sen, Arunabha

    Earth Orbit (LEO) satellite networks are increasingly being deployed to carry out communicationAnalysis of Low Earth Orbit Satellite Networks with Inter-satellite Links Arunabha Sen #3 Engineering Arizona State University Tempe, AZ 85287, USA Abstract Low Earth Orbit (LEO) satellite networks

  20. Reliable Multicast Transport by Satellite: a Hybrid Satellite/Terrestrial Solution with Erasure Codes

    Computer Technologies and Information Sciences Websites

    Mailhes, Corinne

    multipoint communication service. In the context of reliable multicast communications, a new hybrid satellite/terrestrial approach is proposed. It aims at reducing the overall communication cost using satellite broadcasting onlyReliable Multicast Transport by Satellite: a Hybrid Satellite/Terrestrial Solution with Erasure

  1. Information Delivery Through Broadcasting in Satellite Communication Networks

    Engineering Websites

    Tassiulas, Leandros

    Information Delivery Through Broadcasting in Satellite Communication Networks Leandros Tassiulas­range multicasting capability of satellites and the asymmetry of satellite communications (high bandwidth downlink. We consider a data broadcasting model that is encountered in most asymmetric satellite communication

  2. SCTP over Satellite Networks Shaojian Fu

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    SCTP over Satellite Networks Shaojian Fu Mohammed Atiquzzaman School of Computer Science University of Oklahoma, Norman, OK 73019-6151. William Ivancic Satellite Networks & Architectures Branch NASA Glenn of SCTP for data communications over satellite links. We describe SCTP features that allow SCTP to bet

  3. Extracting River Discharge from Satellite Altimetry

    Geosciences Websites

    Stuttgart, Universität

    Extracting River Discharge from Satellite Altimetry M. J. Tourian1,2, N. Sneeuw1, A. Bárdossy2, such as satellite altimetry, have been in- vestigated for monitoring inland water level. In this contribution we. The prerequisite for computing a high-quality level-discharge is a reliable level from satellite altimetry

  4. Relations between Kauffman and Homfly satellite invariants

    Mathematics Websites

    Morton, Hugh

    Relations between Kauffman and Homfly satellite invariants H. R. Morton and N. D. A. Ryder, to the general Kauffman and Homfly satellite invariants. 1 Introduction The result of Rudolph [5] relating. In this paper we show how Rudolph's result can be extended to general Kauffman satellite invariants. Our results

  5. MICHAELMATSON NOAA National Earth Satellite Service

    Environmental Sciences and Ecology Websites

    Dozier, Jeff

    MICHAELMATSON NOAA National Earth Satellite Service Washington, DC 20233 JEFFDOZIER Department the 3.8-pm and 11-pm sensors on board the NOAA-6 satellite. INTRODUCTION THE THIRD-GENERATION,polar orbiting, TIROS-N series of environmental satellites provides two thermal infrared (IR) channels for twice

  6. Using Satellite Data to Forecast . Bleaching Events

    Environmental Sciences and Ecology Websites

    1 Using Satellite Data to Forecast . Bleaching Events . By Tyler Christensen . NOAA Coral Reef Watch Satellite Imagery Worksheet The main condition that is linked to coral bleaching is unusually high water temperature. Your assignment is to use satellite data to investigate whether this condition

  7. HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES

    Mathematics Websites

    Politècnica de Catalunya, Universitat

    HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES Jaume Llibre and Merc`e Oll'e Dept. Matem@ma1.upc.es Abstract We consider the motion of coorbital satellites in the framework of the Restricted satellites Janus and Epimetheus. Key words and expressions: coorbital motion ­ horseshoe periodic orbits ­ Re

  8. THREE-BODY CAPTURE OF IRREGULAR SATELLITES

    Physics Websites

    Hamilton, Douglas P.

    ­ 1 ­ THREE-BODY CAPTURE OF IRREGULAR SATELLITES: APPLICATION TO JUPITER Catherine Philpott1 satellites of the giant planets: capture of one member of a 100-km binary asteroid after tidal disruption to the observed orbits of the irregular satellites. Instead, the long-lived capture orbits subsequently evolve

  9. Eavesdropping on Satellite Telecommunication Benedikt Driessen

    Multidisciplinary Databases and Resources Websites

    International Association for Cryptologic Research (IACR)

    Eavesdropping on Satellite Telecommunication Systems draft Benedikt Driessen Horst-Goertz Institute own communication in the Thuraya satellite network. We have used open-source software to build in the competing satellite communication standards GMR-1 and GMR-2. To break Thu- raya's encryption (which

  10. A Satellite LO system B. G. Clark

    Physics Websites

    Groppi, Christopher

    system was that the satellite beacons being used for the purpose are actually very good oscillators on the satellite carrying the beacon. The analysis below ignores the dispersive e#11;ects of the ionosphere, which, looking at the satellite beacon. The beacon is radiating at frequency (angular) f : exp(if t

  11. Instant Active Positioning with One LEO Satellite

    Engineering Websites

    Levanon, Nadav

    on the earth's surface and a single low earth orbit LEO satellite makes it possible to derive range and range and low-rate data Z .communication to user terminals UTs on the earth. The satellite constellation includes 48 low Z .earth orbit LEO satellites at a height of 1400 km, arranged in eight orbits

  12. The Aerospace Corporation 2009 Communication Satellite Systems

    Computer Technologies and Information Sciences Websites

    Low, Steven H.

    © The Aerospace Corporation 2009 Communication Satellite Systems Trends and Network Aspects Paul://www.aero.org/ Lee Center, Caltech 13 April 2009 #12;22 Communication Satellites · Brief History by Decade · Trends: ­ Communication Satellites, fifth edition, by D. Martin, P. Anderson, L. Bartamian, Aerospace / AIAA Press, 2006

  13. Satellite atmospheres Melissa A. McGrath

    Physics Websites

    Johnson, Robert E.

    19 Satellite atmospheres Melissa A. McGrath Space Telescope Science Institute Emmanuel Lellouch University of Virginia 19.1 INTRODUCTION Study of the Galilean satellite atmospheres is a field that has). At the time of that book, only one of these satellites, Io, was thought to possess an atmosphere, although

  14. Electromagnetic Formation Flight of Satellite Arrays

    Engineering Websites

    Electromagnetic Formation Flight of Satellite Arrays Daniel W. Kwon and David W. Miller February 2005 SSL # 2-05 #12;#12;Electromagnetic Formation Flight of Satellite Arrays By DANIEL W. KWON S;#12;Electromagnetic Formation Flight of Satellite Arrays by DANIEL W. KWON Submitted to the Department of Aeronautics

  15. Dynamics and Control of Electromagnetic Satellite Formations

    Engineering Websites

    Dynamics and Control of Electromagnetic Satellite Formations Umair Ahsun, David W. Miller June 2007 SSL # 12-07 #12;2 #12;Dynamics and Control of Electromagnetic Satellite Formations by Umair Ahsun B page] #12;3 Dynamics and Control of Electromagnetic Satellite Formations by Umair Ahsun Abstract

  16. NOAA Satellite and Information Service The National Environmental Satellite, Data, and Information Service (NESDIS) is dedicated to providing

    Environmental Sciences and Ecology Websites

    NOAA Satellite and Information Service Mission The National Environmental Satellite, Data satellites and other sources to promote, protect, and enhance the Nation's economy, security, environment the Nation's operational environmental satellites, · operates the NOAA National Data Centers, · provides data

  17. A satellite is a platform. A platform carries a sensor. A sensor makes measurements. Advantages of Satellites

    Geosciences Websites

    Small, Christopher

    Satellites A satellite is a platform. A platform carries a sensor. A sensor makes measurements. Advantages of Satellites: Greater altitude than Aircraft Greater platform speed - covers more territory coverage Longer duration --> homogeneous data, repeat observations Disadvantages of Satellites: Greater

  18. VT iDirect, Inc. Secure Satellite Broadband Solutions

    Physics Websites

    VT iDirect, Inc. Secure Satellite Broadband Solutions Modules Names: Evolution e8350 ­ Satellite Router [1], iConnex e800 ­Satellite Router Board [2], iConnex e850MP ­ Satellite Router Board [3], iConnex e850MP-IND Satellite Router Board [4], iConnex e850MP-IND with Heat Sink Satellite Router Board [5

  19. Satellite decay in flattened dark matter haloes

    Astrophysics (arXiv)

    Jorge Penarrubia; Pavel Kroupa; Christian M. Boily

    2002-02-13

    We carry out a set of self-consistent N-body calculations to compare the decay rates of satellite dwarf galaxies orbiting a disc galaxy embedded in a dark matter halo (DMH). We consider both spherical and oblate axisymmetric DMHs of aspect ratio q_h=0.6. The satellites are given different initial orbital inclinations, orbital periods and mass. The live flattened DMHs with embedded discs and bulges are set-up using a new fast algorithm, MaGalie (Boily, Kroupa and Pe\\~{n}arrubia 2001). We find that the range of survival times of satellites within a flattened DMH becomes of the order of 100% larger than the same satellites within a spherical DMH. In the oblate DMH, satellites on polar orbits have the longest survival time, whereas satellites on coplanar prograde orbits are destroyed most rapidly. The orbital plane of a satellite tilts as a result of anisotropic dynamical friction, causing the satellite's orbit to align with the plane of symmetry of the DMH. Polar orbits are not subjected to alignment. Therefore the decay of a satellites in an axisymmetric DMH may provide a natural explanation for the observed lack of satellites within (0-30) degrees of their host galaxy's disc (Holmberg 1969; Zaritsky and Gonz\\'alez 1999). The computations furthermore indicate that the evolution of the orbital eccentricity $e$ is highly dependent of its initial value e(t=0) and the DMH's shape. We also discuss some implications of flattened DMHs for satellite debris streams.

  20. On the Orbits of Infalling Satellite Halos

    CERN Preprints

    Wetzel, Andrew R

    2010-01-01

    The orbital properties of infalling satellite halos set the initial conditions which control the subsequent evolution of subhalos and the galaxies that they host, with implications for mass stripping, star formation quenching, and merging. Using a high-resolution, cosmological N-body simulation, I examine the orbital parameters of satellite halos as they merge with larger host halos, focusing primarily on orbital circularity and pericenter. I explore in detail how these orbital parameters depend on mass and redshift. Satellite orbits become more radial and plunge deeper into their host halo at higher host halo mass, but they do not significantly depend on satellite halo mass. Additionally, satellite orbits become more radial and plunge deeper into their host halos at higher redshift. I also examine satellite velocities, finding that most satellites infall with less specific angular momentum than their host halo but are `hotter' than the host virial circular velocity. I discuss the implications of these result...

  1. Satellite abundances around bright isolated galaxies

    CERN Preprints

    Wang, Wenting

    2012-01-01

    We study satellite galaxy abundances in SDSS by counting photometric galaxies around isolated bright primaries. We present results as a function of the luminosity, stellar mass and colour of the satellites, and of the stellar mass and colour of the primaries. For massive primaries the luminosity and stellar mass functions of satellites are similar in shape to those of field galaxies, but for lower mass primaries they are significantly steeper. The steepening is particularly marked for the stellar mass function. Satellite abundance increases strongly with primary stellar mass, approximately in proportion to expected dark halo mass. Massive red primaries have up to a factor of 2 more satellites than blue ones of the same stellar mass. Satellite galaxies are systematically redder than field galaxies of the same stellar mass. Satellites are also systematically redder around more massive primaries. At fixed primary mass, they are redder around red primaries. We select similarly isolated galaxies from mock catalogu...

  2. Discs of Satellites: the new dwarf spheroidals

    CERN Preprints

    Metz, Manuel; Jerjen, Helmut

    2009-01-01

    The spatial distributions of the most recently discovered ultra faint dwarf satellites around the Milky Way and the Andromeda galaxy are compared to the previously reported discs-of-satellites (DoS) of their host galaxies. In our investigation we pay special attention to the selection bias introduced due to the limited sky coverage of SDSS. We find that the new Milky Way satellite galaxies follow closely the DoS defined by the more luminous dwarfs, thereby further emphasizing the statistical significance of this feature in the Galactic halo. We also notice a deficit of satellite galaxies with Galactocentric distances larger than 100 kpc that are away from the disc-of-satellites of the Milky Way. In the case of Andromeda, we obtain similar results, naturally complementing our previous finding and strengthening the notion that the discs-of-satellites are optical manifestations of a phase-space correlation of satellite galaxies.

  3. Sweeping and shaking dwarf satellites

    Astrophysics (arXiv)

    Lucio Mayer; James Wadsley

    2003-09-02

    We present the first high-resolution N-Body/SPH simulations that follow the evolution of low surface brightness disk satellites in a primary halo containing both dark matter and a hot gas component. Tidal shocks turn the stellar disk into a spheroid with low $v/\\sigma$ and remove most of the outer dark and baryonic mass. In addition, by weakening the potential well of the dwarf, tides enhance the effect of ram pressure, and the gas is stripped down to radius three times smaller than the stellar component A very low gas/stars ratio results after several Gyr, similarly to what seen in dwarf spheroidal satellites of the Milky Way and M31.

  4. Star Formation in Satellite Galaxies

    Astrophysics (arXiv)

    Jose G. Funes SJ; Carlos M. Gutierrez; Francisco Prada; Marco Azzaro; Marcelo B. Ribeiro

    2003-09-22

    The study of satellite galaxies can provide information on the merging and aggregation processes which, according to the hierarchical clustering models, form the larger spiral galaxies we observe. With the aim of testing hierarchical models of galaxy formation, we have conducted an observational program which comprises H$\\alpha$ imaging for both the parent and the satellite galaxies, taken from the compilation by Zaritsky et al. (1997) that contains 115 galaxies orbiting 69 primary isolated spiral galaxies. We have observed a subsample of 37 spiral and irregular galaxies taken from the compilation mentioned above. The aim of this study is to determine star formation properties of the sample galaxies. In this work we present the preliminary results of this program that we have carried out with the 1.8-m Vatican Telescope (VATT).

  5. Asteroseismology with the WIRE satellite

    Astrophysics (arXiv)

    H. Bruntt

    2007-02-01

    I give a summary of results from the WIRE satellite, which has been used to observe bright stars from 1999-2000 and 2003-2006. The WIRE targets are monitored for up to five weeks with a duty cycle of 30-40%. The aim has been to characterize the flux variation of stars across the Hertzsprung-Russell diagram. I present an overview of the results for solar-like stars, delta Scuti stars, giant stars, and eclipsing binaries.

  6. Controls Field Exam Consider a satellite orbiting the earth. The satellite's distance from earth is denoted by r(t). The satellite

    Engineering Websites

    de Weck, Olivier L.

    Controls Field Exam Question 1 Consider a satellite orbiting the earth. The satellite's distance from earth is denoted by r(t). The satellite is put on orbit such that its nominal distance to earth on the satellite. The dynamics of the satellite can be described the following differential equation: ¨r(t) = 2 r

  7. The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites

    Astrophysics (arXiv)

    Manuel Metz; Pavel Kroupa; Noam I. Libeskind

    2008-02-26

    Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter (CDM) simulations, tailored specifically to solve the MW satellite problem. We show that the CDM satellite orbital poles are fully consistent with being drawn from a random distribution, while the MW satellite orbital poles indicate that the disc-of-satellites of the Milky Way is rotationally supported. Furthermore, the bootstrapping analysis of the spatial distribution of theoretical CDM satellites also shows that they are consistent with being randomly drawn. The theoretical CDM satellite population thus shows a significantly different orbital and spatial distribution than the MW satellites, most probably indicating that the majority of the latter are of tidal origin rather than being DM dominated sub-structures. A statistic is presented that can be used to test a possible correlation of satellite galaxy orbits with their spatial distribution.

  8. The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites

    CERN Preprints

    Metz, Manuel; Libeskind, Noam I

    2008-01-01

    Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter (CDM) simulations, tailored specifically to solve the MW satellite problem. We show that the CDM satellite orbital poles are fully consistent with being drawn from a random distribution, while the MW satellite orbital poles indicate that the disc-of-satellites of the Milky Way is rotationally supported. Furthermore, the bootstrapping analysis of the spatial distribution of theoretical CDM satellites also shows that they are consistent with being randomly drawn. The theoretical CDM satellite population thus shows a significantly different orbital and spatial distribution than the MW satellites, most probably indicating that the majority of the latter are of tidal origin rather than being DM dominated sub-structures. A statistic is presented that can be used to test a possible correlation of satellite galaxy orbits...

  9. Satellite-based quantum clock synchronization

    CERN Preprints

    Wang, Jieci; Jing, Jiliang; Fan, Heng

    2015-01-01

    We propose a practical satellite-based quantum clock synchronization scheme with dispersion cancellation and by taking into account effects of gravitational frequency shift of the Earth. Two frequency entangled pulses are employed to synchronize two clocks, one at a ground station and the other at a satellite. The time discrepancy of the two clocks is introduced into the pulses by moving mirrors and is extracted by measuring the coincidence rate of the pulses in the interferometer. We find that the pulses are distorted due to effects of the gravitational frequency shift when they propagate between the Earth and the satellite. It is shown that the coincidence rate as well as precision of the time discrepancy are remarkably affected by gravitational frequency shift effects both for the low earth orbits satellite and geostationary earth orbits satellite cases. We also find that the precision of the clock synchronization are sensitive to the source parameters and the altitude of the satellite. Our proposal can be...

  10. The Satellite-substructure Connection

    Astrophysics (arXiv)

    James E. Taylor; Arif Babul; Joseph Silk

    2003-11-28

    We describe our recent attempts to model substructure in dark matter halos down to very small masses, using a semi-analytic model of halo formation. The results suggest that numerical simulations of halo formation may still be missing substructure in the central regions of halos due to purely numerical effects. If confirmed, this central 'overmerging' problem will have important consequences for the interpretation of lensing measurements of substructure. We also show that the spatial distribution of subhalos relative to the satellite companions of the Milky Way rules out at least one simple model of how dwarf galaxies form in low-mass halos.

  11. SaVi: satellite constellation visualization

    CERN Preprints

    Wood, Lloyd

    2012-01-01

    SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational and teaching purposes. SaVi is introduced and described briefly here.

  12. Satellite Ecology: The Dearth of Environment Dependence

    Astrophysics (arXiv)

    Frank C. van den Bosch; Anna Pasquali; Xiaohu Yang; H. J. Mo; Simone Weinmann; Daniel H. McIntosh; Daniel Aquino

    2008-05-01

    Using the Sloan Digital Sky Survey (SDSS) galaxy group catalogue of Yang et al. (2007), we study the average colour and average concentration of satellite galaxies as function of (i) their stellar mass, (ii) their group mass, and (iii) their group-centric radius. We find that the colours and concentrations of satellite galaxies are (almost) completely determined by their stellar mass. In particular, at fixed stellar mass, the average colours and concentrations of satellite galaxies are independent of either halo mass or halo-centric radius. We find clear evidence for mass segregation of satellite galaxies in haloes of all masses, and argue that this explains why satellites at smaller halo-centric radii are somewhat redder and somewhat more concentrated. In addition, the weak colour and concentration dependence of satellite galaxies on halo mass is simply a reflection of the fact that more massive haloes host, on average, more massive satellites. Combining these results with the fact that satellite galaxies are, on average, redder and somewhat more concentrated than central galaxies of the same stellar mass, the following picture emerges: galaxies become redder and somewhat more concentrated once they fall into a bigger halo (i.e., once they become a satellite galaxy). This is a clear manifestation of environment dependence. However, there is no indication that the magnitude of the transformation (or its timescale) depends on environment; a galaxy undergoes a transition when it becomes a satellite, but it does not matter whether it becomes a satellite of a small (Milky Way sized) halo, or of a massive cluster. We discuss the implication of this `dearth' of environment dependence for the physical processes responsible for transforming satellite galaxies.

  13. A Search for Satellite around Ceres

    CERN Preprints

    Bieryla, A; Young, E F; McFadden, L A; Russell, C T; Stern, S A; Sykes, M V; Gladman, B

    2011-01-01

    We conducted a satellite search around the dwarf planet 1 Ceres using Hubble Space Telescope and ground-based Palomar data. No candidate objects were found orbiting Ceres in its entire stability region down to ~500km from the surface of Ceres. Assuming a satellite would have the same albedo as Ceres, which has a visual geometric albedo of 0.07-0.10, our detection limit is sensitive to satellites larger than 1-2 km in diameter.

  14. Origin of Europa and the Galilean Satellites

    Astrophysics (arXiv)

    Robin M. Canup; William R. Ward

    2008-12-30

    Europa is believed to have formed near the very end of Jupiter's own accretion, within a circumplanetary disk of gas and solid particles. We review the formation of the Galilean satellites in the context of current constraints and understanding of giant planet formation, focusing on recent models of satellite growth within a circumjovian accretion disk produced during the final stages of gas inflow to Jupiter. In such a disk, the Galilean satellites would have accreted slowly, in more than 10^5 yr, and in a low pressure, low gas density environment. Gravitational interactions between the satellites and the gas disk lead to inward orbital migration and loss of satellites to Jupiter. Such effects tend to select for a maximum satellite mass and a common total satellite system mass compared to the planet's mass. One implication is that multiple satellite systems may have formed and been lost during the final stages of Jupiter's growth, with the Galilean satellites being the last generation that survived as gas inflow to Jupiter ended. We conclude by discussing open issues and implications for Europa's conditions of formation.

  15. Satellites of the largest Kuiper belt objects

    CERN Preprints

    Brown, M E; Bouchez, A H; Le Mignant, D; Campbell, R D; Chin, J C Y; Conrad, A; Hartman, S K; Johansson, E M; Lafon, R E; Rabinowitz, D L; Stomski, P J; Summers, D M; Trujillo, C A; Wizinowich, P L

    2006-01-01

    We have searched the four brightest objects in the Kuiper belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known), 2003 EL61, and 2003 UB313. The object 2005 FY9, the brightest Kuiper belt object after Pluto, does not have a satellite detectable within 0.4 arcseconds with a brightness of more than 0.5% of the primary. The presence of satellites to 3 of the 4 brightest Kuiper belt objects is inconsistent with the fraction of satellites in the Kuiper belt at large at the 99.1% confidence level, suggesting a different formation mechanism for these largest KBO satellites. The satellites of 2003 EL61 and 2003 UB313, with fractional brightnesses of 5% and 2% of their primaries, respectively, are significantly fainter relative to their primaries than other known Kuiper belt object satellites, again pointing to possible differences in their origin.

  16. Satellites of the largest Kuiper belt objects

    Astrophysics (arXiv)

    M. E. Brown; M. A. van Dam; A. H. Bouchez; D. Le Mignant; R. D. Campbell; J. C. Y. Chin; A. Conrad; S. K. Hartman; E. M. Johansson; R. E. Lafon; D. L. Rabinowitz; P. J. Stomski, Jr.; D. M. Summers; C. A. Trujillo; P. L. Wizinowich

    2005-10-03

    We have searched the four brightest objects in the Kuiper belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known), 2003 EL61, and 2003 UB313. The object 2005 FY9, the brightest Kuiper belt object after Pluto, does not have a satellite detectable within 0.4 arcseconds with a brightness of more than 0.5% of the primary. The presence of satellites to 3 of the 4 brightest Kuiper belt objects is inconsistent with the fraction of satellites in the Kuiper belt at large at the 99.1% confidence level, suggesting a different formation mechanism for these largest KBO satellites. The satellites of 2003 EL61 and 2003 UB313, with fractional brightnesses of 5% and 2% of their primaries, respectively, are significantly fainter relative to their primaries than other known Kuiper belt object satellites, again pointing to possible differences in their origin.

  17. Origin of Europa and the Galilean Satellites

    CERN Preprints

    Canup, Robin M

    2008-01-01

    Europa is believed to have formed near the very end of Jupiter's own accretion, within a circumplanetary disk of gas and solid particles. We review the formation of the Galilean satellites in the context of current constraints and understanding of giant planet formation, focusing on recent models of satellite growth within a circumjovian accretion disk produced during the final stages of gas inflow to Jupiter. In such a disk, the Galilean satellites would have accreted slowly, in more than 10^5 yr, and in a low pressure, low gas density environment. Gravitational interactions between the satellites and the gas disk lead to inward orbital migration and loss of satellites to Jupiter. Such effects tend to select for a maximum satellite mass and a common total satellite system mass compared to the planet's mass. One implication is that multiple satellite systems may have formed and been lost during the final stages of Jupiter's growth, with the Galilean satellites being the last generation that survived as gas in...

  18. Ravens satellite mission concept study

    CERN Preprints

    Donovan, Eric F

    2011-01-01

    The concept for Ravens satellite mission was proposed in response to a CSA AO for potential Canadian mission contributions to the International Living With a Star (ILWS) program. Ravens was conceived of to fill an important gap in the ILWS program: global imaging. Ravens will build on the heritage of world-class global imaging carried out in Canada. It would do much more than provide global observations to complete the system level capabilities of ILWS. Ravens would be comprised of two satellites on elliptical polar orbits, relatively phased on those orbits to provide the first-ever continuous (ie., 24 hours per day 7 days per week) global imaging of the northern hemisphere auroral and polar cap regions. This would provide the first-ever unbroken sequences of global images of the auroral response during long duration geomagnetic processes like storms and steady magnetospheric convection events. Ravens could track the spatio-temporal evolution of the global electron and proton auroral distribution, and would o...

  19. Dynamics of the Galaxy's Satellites

    Astrophysics (arXiv)

    James Binney

    2000-06-28

    The Milky Way's satellites provide unique information about the density of the Galactic halo at large radii. The inclusion of even a few rather inaccurate proper motions resolves an ambiguity in older mass estimates in favour of higher values. Many of the satellites are concentrated into streams. The dynamics of the Magellanic Stream provided an early indication that the halo reaches out to beyond 100 kpc. Tidal forces between the Clouds are currently disturbing the Clouds' internal dynamics. One would expect this damage to worsen rapidly as the tidal field of the MW excites the eccentricity of the Clouds' mutual orbit. This process, which has yet to be completely modelled, is important for understanding the degree of self-lensing in searches for gravitational lensing events. The Sagittarius Dwarf galaxy very likely contributes significantly to the Galactic warp. The direction of the warp's line of nodes is incorrectly predicted by the simplest models of the Dwarf's orbit. More sophisticated models, in which a complex distribution of stripped dark matter is predicted, may be more successful.

  20. Satellite Services Rate Schedule Effective March 26, 2014

    Computer Technologies and Information Sciences Websites

    Acton, Scott

    Satellite Services Rate Schedule Effective March 26, 2014 SCPS offers satellite communications Satellite Services email satellite@virginia.edu or call 434-982-5268. Services UVa/State Regular* UVa Studio to Vyvx $335 $500 $400 $600 IFB & PL $15 $20 $20 $30 Tape Playback $65 $100 $85 $125 Satellite

  1. Satellite Transport Protocol (STP): An SSCOPbased Transport Protocol for Datagram Satellite Networks

    Computer Technologies and Information Sciences Websites

    California at Berkeley, University of

    1 Satellite Transport Protocol (STP): An SSCOP­based Transport Protocol for Datagram Satellite­based protocol, the Service Specific Connection Oriented Protocol (SSCOP), for use as a transport protocol. We then compare the performance of the modified protocol (the Satellite Transport Protocol, or STP

  2. PERFORMANCE EVALUATION OF LEO SATELLITE CONSTELLATIONS WITH INTER-SATELLITE LINKS

    Computer Technologies and Information Sciences Websites

    Papapetrou, Evaggelos

    1 PERFORMANCE EVALUATION OF LEO SATELLITE CONSTELLATIONS WITH INTER-SATELLITE LINKS UNDER SELF orbit (LEO) satellite constellations, used for the interconnection of high-speed networks, is presented worldwide for supporting real-time communications. Low Earth Orbit (LEO) constellations, specially those

  3. Satellite based retrieval of aerosol optical thickness: The effect of sun and satellite geometry

    Environmental Sciences and Ecology Websites

    Satellite based retrieval of aerosol optical thickness: The effect of sun and satellite geometry-pixel size cloud problems. We analyze 18 pairs of images, taken close to nadir and back along the track of aerosol optical thickness: The effect of sun and satellite geometry, Geophys. Res. Lett., 30(11), 1553

  4. Fig.1. A hybrid network of MANET-satellite-Internet. Adaptive Hierarchical Resource Management for Satellite Channel in Hybrid MANET-

    Engineering Websites

    Baras, John S.

    MANET MANET MANET Service center Internet Satellite MANET MANET MANET Service center Internet Satellite Fig.1. A hybrid network of MANET-satellite-Internet. Adaptive Hierarchical Resource Management for Satellite Channel in Hybrid MANET- Satellite-Internet Network Nelson X. Liu Xiaoming Zhou John S. Baras

  5. Title: Satellite Streetview: Nova Scotia Data Creator /

    Computer Technologies and Information Sciences Websites

    Title: Satellite Streetview: Nova Scotia Data Creator / Copyright Owner: DMTI Spatial Inc/A Updates: N/A Abstract: Satellite images generated for cities and/or regions in Nova Scotia. Areas include Coordinates: -141 (west), -43 (east), 84 (north), 41.5 (south) Index Map: N/A Keywords (Place): Canada; Nova

  6. Title: Satellite Streetview: New Brunswick Data Creator /

    Computer Technologies and Information Sciences Websites

    Title: Satellite Streetview: New Brunswick Data Creator / Copyright Owner: DMTI Spatial Inc/A Updates: N/A Abstract: Satellite images generated for cities and/or regions in New Brunswick. Areas (east), 84 (north), 41.5 (south) Index Map: N/A Keywords (Place): Canada; New Brunswick; Fredericton

  7. Satellite decay in flattened dark matter haloes

    CERN Preprints

    Penarrubia-Garrido, J; Boily, C M; Penarrubia, Jorge; Kroupa, Pavel; Boily, Christian M.

    2002-01-01

    We carry out a set of self-consistent N-body calculations to compare the decay rates of satellite dwarf galaxies orbiting a disc galaxy embedded in a dark matter halo (DMH). We consider both spherical and oblate axisymmetric DMHs of aspect ratio q_h=0.6. The satellites are given different initial orbital inclinations, orbital periods and mass. The live flattened DMHs with embedded discs and bulges are set-up using a new fast algorithm, MaGalie (Boily, Kroupa and Pe\\~{n}arrubia 2001). We find that the range of survival times of satellites within a flattened DMH becomes of the order of 100% larger than the same satellites within a spherical DMH. In the oblate DMH, satellites on polar orbits have the longest survival time, whereas satellites on coplanar prograde orbits are destroyed most rapidly. The orbital plane of a satellite tilts as a result of anisotropic dynamical friction, causing the satellite's orbit to align with the plane of symmetry of the DMH. Polar orbits are not subjected to alignment. Therefore ...

  8. MFR PAPER 1230 Finding Fish With Satellites

    Environmental Sciences and Ecology Websites

    -The LANDSA T (Land Satellite) Investigation began in April 1975 to determine if satellites can be used to collect supplementary and corroborative data on chlorophyll, surface water temperature, salinity, color, turbidity, and fish school location and size. Data analyses so far indicate that water color and turbidity

  9. DISASTER RECOVERY APPLICATIONS FOR SATELLITE COMMUNICATIONS SYSTEMS

    Engineering Websites

    Kruse, Hans

    DISASTER RECOVERY APPLICATIONS FOR SATELLITE COMMUNICATIONS SYSTEMS Hans Kruse, Tony Mele, Sara by Ohio University and The Huntington National Bank. Our aim was to determine if ACTS-based data in the ACTS system. Finally, we project possible applications for satellite based data communication services

  10. Satellite Navigation Integrity Assurance: Lessons Learned

    Engineering Websites

    Stanford University

    Satellite Navigation Integrity Assurance: Lessons Learned from Hurricane Katrina ION GNSS 2008 by the FAA Satellite Navigation Program Office #12;17 September 2008 Lessons Learned from Hurricane Katrina 2 Outline · The Destruction of Much of Greater New Orleans in late August 2005 (Hurricane Katrina) · Flaws

  11. Satellite galaxies in nearby groups of galaxies

    CERN Preprints

    Vennik, J

    2015-01-01

    We analyse distribution, kinematics and star-formation (SF) properties of satellite galaxies in three different samples of nearby groups. We find that studied groups are generally well approximated by low-concentration NFW model, show a variety of LOS velocity dispersion profiles and signs of SF quenching in outskirts of dwarf satellite galaxies.

  12. AbstractThe satellite-borne

    Multidisciplinary Databases and Resources Websites

    Kansas, University of

    Abstract­The satellite-borne Scanning for a Satellite Radar Wind Sounder (RAWS) RK Moore, B. Beh, and S. Song University of Kansas, Radar Systems and Remote Sensing Laboratory 2291 Irving Hill Road Radar Wind Sounder (RAWS) is a proposed radar capable of measuring wind alofi using Doppler shifts

  13. Global Electrical Conductivity Magnetic Satellite Induction Studies

    Fossil Fuels Websites

    Constable, Steve

    .Constable SCRIPPSINST ITUTION OF OCE ANOGRAPHY UCSD #12;Electromagnetic Induction: Faraday's Law states that a timeGlobal Electrical Conductivity and Magnetic Satellite Induction Studies Steven Constable Catherine conductivity · Background: EM induction · Some satellite results 2ndCHAMPMeeting, September2003 c S

  14. INTRODUCTION Satellites contain onboard equipment for sens-

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    INTRODUCTION Satellites contain onboard equipment for sens- ing Earth and space, and communications links that transmit the data back to Earth for pro- cessing. Depending on altitude and movement, satellites are classified into three types: geosyn- chronous Earth orbit (GEO), medium Earth orbit (MEO

  15. Advantages of Satellites: Greater altitude than Aircraft

    Geosciences Websites

    Small, Christopher

    is closest to the earth is the Perigee and the point at which it is furthest away is theApogee. The geometry of satellite orbits results in both Ascending and Descending nodes. If the satellite orbits the earth in the direction of the earth's rotation then the orbit is called Prograde; if it orbits in the opposite direction

  16. Numerical Homotopy Algorithms for Satellite Trajectory Control

    Mathematics Websites

    Verschelde, Jan

    ]) to a control engineering problem, which appeared as case study in the literature. Our methodology extendsNumerical Homotopy Algorithms for Satellite Trajectory Control by Pole Placement 1 Jan Verschelde 2 is to illustrate the application of numerical homotopy algorithms to control the trajectory of a satellite. We

  17. Numerical Homotopy Algorithms for Satellite Trajectory Control

    Mathematics Websites

    Verschelde, Jan

    of our knowledge ­ to apply the new Pieri homotopies (see [6], [7] and [10]) to a control engineeringNumerical Homotopy Algorithms for Satellite Trajectory Control by Pole Placement1 Jan Verschelde2 is to illustrate the application of numerical homotopy algorithms to control the trajectory of a satellite. We

  18. COORDINATED CONTROL OF SATELLITES: THE ATTITUDE CASE

    Engineering Websites

    Gravdahl, Jan Tommy

    by means of reaction wheels and magnetic torquers. In this approach one satellite is defined as the leader. In addition we propose a momentum dumping scheme for satellites with redundant reaction wheel assemblies. I of the for- mation as an agent and the control action for each agent is defined by a weighted average

  19. Observing geomagnetic induction in magnetic satellite measurements and associated

    Geosciences Websites

    Key, Kerry

    Observing geomagnetic induction in magnetic satellite measurements and associated implications distributed land observatories. Satellite-borne magnetometers, such as flown on Magsat, Ørsted, and Champ by harmonic Dst (``disturbance storm time'') excitation of the magnetospheric ring current in satellite

  20. A Feedback Implosion Suppression Algorithm for Satellite Reliable Multicast

    Engineering Websites

    Baras, John S.

    A Feedback Implosion Suppression Algorithm for Satellite Reliable Multicast Gun Akkor, John S. Baras, and Michael Hadjitheodosiou Center for Satellite and Hybrid Communication Networks, Institute multicast transport protocols operating over a satellite network. A reliable transport protocol needs

  1. Ion Micro-Propulsion and Cost Modeling for Satellite Clusters

    Engineering Websites

    of satellites in a cluster are altered by "tidal" accelerations which are a function of the cluster baseline the relative positions of the satellites within allowable tolerances. Satellite mass, volume, and power

  2. Capture of Irregular Satellites at Jupiter

    CERN Preprints

    Nesvorny, D; Deienno, R

    2014-01-01

    The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early Solar System instability when encounters between the outer planets occurred (Nesvorny, Vokrouhlicky & Morbidelli 2007, AJ 133; hereafter NVM07). NVM07 already showed that the irregular satellites of Saturn, Uranus and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary d...

  3. Sinking Satellites and Tilting Disk Galaxies

    Astrophysics (arXiv)

    Siqin Huang; R. G. Carlberg

    1995-11-16

    The infall of a satellite galaxy onto a galactic disk generally brings in angular momentum that is not aligned with the axis of the disk. The main dynamical issues addressed are what fraction of the orbital angular momentum of the satellite and the associated energy is added to the disk, as opposed to being left in the halo, and whether the absorbed fraction is added coherently or thermalized in the disk. By employing fully self-consistent disk+halo+satellite N-body simulations, we study the particular case of the satellite and main halo having similar density profiles, with internal velocities having the ``cosmological'' scaling $\\sigma\\propto M^{1/3}$. We find that most of the orbital angular momentum of the infalling satellite is left in the tidally stripped satellite remnants, with only $2\\%$, $6\\%$ and $9\\%$ of the orbital angular momentum being transferred to disks and halos for $10\\%$, $20\\%$ and $30\\%$ disk-mass satellites respectively. Because the disks are tilted by the infall of $10\\%$, $20\\%$ and $30\\%$ disk-mass satellites by angles of $(2.9\\pm0.3)^\\circ$, $(6.3\\pm0.1)^\\circ$ and $(9.7\\pm0.2)^\\circ$ respectively, the kinetic energy associated with the vertical motion in the initial coordinate frame of the three disks is respectively increased by $(6\\pm3)\\%$, $(26\\pm3)\\%$ and $(51\\pm5)\\%$ whereas the corresponding disk thermal energy associated with the vertical random motion in the tilted coordinate frame is only increased by $(4\\pm3)\\%$, $(6\\pm2)\\%$ and $(10\\pm2)\\%$, respectively. Under our initial conditions, a satellite having up to 20\\% of the disk mass would produce little observable thickening whereas a 30\\% disk-mass satellite produces little observable thickening inside the half-mass radius of the disk but great damage beyond the half-mass radius.

  4. The Orbital Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Stéphane Herbert-Fort; Dennis Zaritsky; Yeun Jin Kim; Jeremy Bailin; James E. Taylor

    2007-11-26

    We measure the distribution of velocities for prograde and retrograde satellite galaxies using a combination of published data and new observations for 78 satellites of 63 extremely isolated disc galaxies (169 satellites total). We find that the velocity distribution is non-Gaussian (>99.9% confidence), but that it can be described as the sum of two Gaussians, one of which is broad (sigma = 176 \\pm 15 km/s), has a mean prograde velocity of 86 \\pm 30 km/s, and contains ~55% of the satellites, while the other is slightly retrograde with a mean velocity of -21 \\pm 22 km/s and sigma = 74 \\pm 18 km/s and contains ~45% of the satellites. Both of these components are present over all projected radii and found in the sample regardless of cuts on primary inclination or satellite disc angle. The double-Gaussian shape, however, becomes more pronounced among satellites of more luminous primaries. We remove the potential dependence of satellite velocity on primary luminosity using the Tully-Fisher relation and still find the velocity distribution to be asymmetric and even more significantly non-Gaussian. The asymmetric velocity distribution demonstrates a connection between the inner, visible disc galaxy and the kinematics of the outer, dark halo. The reach of this connection, extending even beyond the virial radii, suggests that it is imprinted by the satellite infall pattern and large-scale effects, rather than by higher-level dynamical processes in the formation of the central galaxy or late-term evolution of the satellites.

  5. Gas Shepherding by an Infalling Satellite

    Astrophysics (arXiv)

    P. Chang

    2008-05-22

    I calculate the action of a satellite, infalling through dynamical friction, on a coplanar gaseous disk of finite radial extent. The disk tides, raised by the infalling satellite, couple the satellite and disk. Dynamical friction acting on the satellite then shrinks the radius of the coupled satellite-disk system. Thus, the gas is ``shepherded'' to smaller radii. In addition, gas shepherding produces a large surface density enhancement at the disk edge. If the disk edge then becomes gravitationally unstable and fragments, it may give rise to enhanced star formation. On the other hand, if the satellite is sufficiently massive and dense, the gas may be transported from $\\sim 100$ pc to inside of a 10 to 10s of parsecs before completely fragmenting into stars. I argue that gas shepherding may drive the fueling of active galaxies and central starbursts and I compare this scenario to competing scenarios. I argue that sufficiently large and dense super star clusters (acting as the shepherding satellites) can shepherd a gas disk down to ten to tens of parsecs. Inside of ten to tens of parsecs, another mechanism may operate, i.e., cloud-cloud collisions or a marginally (gravitationally) stable disk, that drives the gas $\\lesssim 1$ pc, where it can be viscously accreted, feeding a central engine.

  6. Probing Dark Matter Haloes with Satellite Kinematics

    Astrophysics (arXiv)

    Frank C. van den Bosch; Peder Norberg; H. J. Mo; Xiaohu Yang

    2004-05-14

    Using detailed mock galaxy redshift surveys we investigate to what extent the kinematics of large samples of satellites galaxies extracted from flux-limited surveys can be used to constrain halo masses. Previous host-satellite selection criteria yield relatively large fractions of interlopers and with a velocity distribution that, contrary to what has typically been assumed, differs strongly from uniform. A new adaptive selection criterion is proposed which yields much larger host-satellite samples and with strongly reduced interloper fractions. We show that satellite weighting, which occurs naturally when stacking many host-satellite pairs, introduces a bias towards higher velocity dispersions compared to the true, host-averaged mean. A further bias, in the same direction, is introduced when using flux-limited, rather than volume-limited surveys. We apply our adaptive selection criterion to the 2dFGRS and obtain a sample of 12613 satellite galaxies and 8004 host galaxies. The satellite kinematics are in excellent agreement with predictions based on the conditional luminosity function (CLF), providing independent, dynamical confirmation of the average mass-to-light ratios predicted by the CLF formalism.

  7. Spatial and luminosity distributions of galactic satellites

    CERN Preprints

    Guo, Quan; Eke, Vincent; Frenk, Carlos; Helly, John

    2013-01-01

    We investigate the luminosity functions (LFs) and projected number density profiles of galactic satellites around isolated primaries of different luminosities. We measure these quantities for model satellites placed into the Millennium and Millennium II dark matter simulations by the GALFORM semi-analytic galaxy formation model for different bins of primary galaxy magnitude and we investigate their dependence on satellite luminosity. We compare our model predictions to the data of Guo et al. from the Sloan Digital Sky Survey Data Release 8 (SDSS DR8). First, we use a mock light-cone catalogue to verify that the method we used to count satellites in the SDSS DR8 is unbiased. We find that the radial distributions of model satellites are similar to those around comparable primary galaxies in the SDSS DR8, with only slight differences at low luminosities and small projected radii. However, when splitting the satellites by colour, the model and SDSS satellite systems no longer resemble one another, with many red m...

  8. Luminous satellite galaxies in gravitational lenses

    Astrophysics (arXiv)

    S. E. Bryan; S. Mao; S. T. Kay

    2008-09-18

    Substructures, expected in cold dark matter haloes, have been proposed to explain the anomalous flux ratios in gravitational lenses. About 25% of lenses in the Cosmic Lens All-Sky Survey (CLASS) appear to have luminous satellites within ~ 5 kpc/h of the main lensing galaxies, which are usually at redshift z ~ 0.2-1. In this work we use the Millennium Simulation combined with galaxy catalogues from semi-analytical techniques to study the predicted frequency of such satellites in simulated haloes. The fraction of haloes that host bright satellites within the (projected) central regions is similar for red and blue hosts and is found to increase as a function of host halo mass and redshift. Specifically, at z = 1, about 11% of galaxy-sized haloes (with masses between 10^{12} M_sun/h and 10^{13} M_sun/h) host bright satellite galaxies within a projected radius of 5 kpc/h. This fraction increases to about 17% (25%) if we consider bright (all) satellites of only group-sized haloes (with masses between 10^{13} M_sun/h and 10^{14} M_sun/h). These results are roughly consistent with the fraction (~ 25%) of CLASS lensing galaxies observed to host luminous satellites. At z = 0, only ~ 3% of galaxy-sized haloes host bright satellite galaxies. The fraction rises to ~ 6%, (10%) if we consider bright (all) satellites of only group-sized haloes at z = 0. However, most of the satellites found in the inner regions are `orphan' galaxies where the dark matter haloes have been completely stripped. Thus the agreement crucially depends on the true survival rate of these `orphan' galaxies. We also discuss the effects of numerical resolution and cosmologies on our results.

  9. Satellite galaxies in cosmological dark matter halos

    Astrophysics (arXiv)

    Stuart P. D. Gill; Alexander Knebe; Brad K. Gibson

    2003-11-28

    We present preliminary results from a series of high-resolution N-body simulations that focus on 8 dark matter halos each of order a million particles within the virial radius. We follow the time evolution of hundreds of individually tracked satellite galaxies and relate their physical properties to the differing halo environmental conditions. Our main science driver is to understand how satellite galaxies lose their mass and react to tidal stripping. Unlike previous work our results are performed in a fully self-consistent cosmological context. The preliminary results demonstrate that while environment may vary considerably with respects to formation time and richness of substructure, the satellites evolve similarly.

  10. Disruption of satellites in cosmological haloes

    Astrophysics (arXiv)

    Giuliano Taffoni; Lucio Mayer; Monica Colpi; Fabio Governato

    2001-09-03

    We investigate how the survival of dark matter satellites inside virialized halos depends on tidal stripping and dynamical friction. We use an analytic approach and then compare the results with N-Body simulations. Both the satellites and the primary halos are similar to cosmological haloes and have NFW density profiles. Satellites can either merge with the primary halo or continue to move on barely perturbed orbits, eventually being disrupted, depending on the relative strength of friction and tidal forces. We propose that their actual fate depends simply on their mass ratio relative to the primary halo.

  11. The Transiting Exoplanet Survey Satellite

    CERN Preprints

    Ricker, George R; Vanderspek, Roland; Latham, David W; Bakos, Gaspar A; Bean, Jacob L; Berta-Thompson, Zachory K; Brown, Timothy M; Buchhave, Lars; Butler, Nathaniel R; Butler, R Paul; Chaplin, William J; Charbonneau, David; Christensen-Dalsgaard, Jorgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, E W; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J; Howard, Andrew W; Ida, Shigeru; Jenkins, Jon; Jernigan, Garrett; Johnson, John Asher; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M; Lin, Douglas; Lissauer, Jack J; MacQueen, Phillip; Marcy, Geoffrey; McCullough, P R; Morton, Timothy D; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, S A; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel

    2014-01-01

    The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I<13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler missio...

  12. The MAP Satellite Feed Horns

    Astrophysics (arXiv)

    C. Barnes; M. Limon; L. Page; C. Bennett; S. Bradley; M. Halpern; G. Hinshaw; N. Jarosik; W. Jones; A. Kogut; S. Meyer; O. Motrunich; G. Tucker; D. Wilkinson; E. J. Wollack

    2003-01-10

    We present the design, manufacturing methods, and characterization of 20 microwave feed horns currently in use on the Microwave Anisotropy Probe (MAP) satellite. The nature of the cosmic microwave background (CMB) anisotropy requires a detailed understanding of the properties of every optical component of a microwave telescope. In particular, the properties of the feeds must be known so that the forward gain and sidelobe response of the telescope can be modeled and so that potential systematic effects may be computed. MAP requires low emissivity, azimuthally symmetric, low-sidelobe feeds in five microwave bands (K, Ka, Q, V, and W) that fit within a constrained geometry. The beam pattern of each feed is modeled and compared with measurements; the agreement is generally excellent to the -60 dB level (80 degrees from the beam peak). This agreement verifies the beam-predicting software and the manufacturing process. The feeds also affect the properties and modeling of the microwave receivers. To this end, we show that the reflection from the feeds is less than -25 dB over most of each band and that their emissivity is acceptable. The feeds meet their multiple requirements.

  13. The MAP Satellite Feed Horns

    CERN Preprints

    Barnes, C; Page, L; Bennett, C; Bradley, S; Halpern, M; Hinshaw, G; Jarosik, N C; Jones, W; Kogut, A J; Meyer, S; Motrunich, O; Tucker, G S; Wilkinson, D; Wollack, E J

    2002-01-01

    We present the design, manufacturing methods, and characterization of 20 microwave feed horns currently in use on the Microwave Anisotropy Probe (MAP) satellite. The nature of the cosmic microwave background (CMB) anisotropy requires a detailed understanding of the properties of every optical component of a microwave telescope. In particular, the properties of the feeds must be known so that the forward gain and sidelobe response of the telescope can be modeled and so that potential systematic effects may be computed. MAP requires low emissivity, azimuthally symmetric, low-sidelobe feeds in five microwave bands (K, Ka, Q, V, and W) that fit within a constrained geometry. The beam pattern of each feed is modeled and compared with measurements; the agreement is generally excellent to the -60 dB level (80 degrees from the beam peak). This agreement verifies the beam-predicting software and the manufacturing process. The feeds also affect the properties and modeling of the microwave receivers. To this end, we sho...

  14. Dark Satellites and Cosmic Reionization

    Astrophysics (arXiv)

    Andrea V. Maccio'; Ben Moore; Joachim Stadel; Doug Potter

    2006-09-06

    A possible explanation of the present discrepancy between the abundance of galactic subhaloes predicted by N-Body simulations with those observed in the Local Group is presented. We study the impact of an early reionization on the baryonic component of the Universe using SPH simulations on group and galactic scales. We use a simplified model for reionization described as an instantaneous increment of the IGM temperature (with 1e5 8). We find that a key role is played by compton cooling (interaction between hot electrons and the CMB photons); at high redshift (z_r>10) this cooling is very efficient and it is able to counteract any heating of the gas within few Myrs. This means that a late reionization is needed (z_r<9) to sufficiently reduce the number of luminous dwarf satellites around our Galaxy. For a reionization redshift z_r=8 and a reionization temperature of T_{IGM}~1e5 K we are able to reproduce the observed number of Local Group dwarf galaxies in our simulations.

  15. Saturn satellites as seen by Cassini Mission

    CERN Preprints

    Coradini, A; Cerroni, P; Filacchione, G; Magni, G; Orosei, R; Tosi, F; Turrini, D

    2009-01-01

    In this paper we will summarize some of the most important results of the Cassini mission concerning the satellites of Saturn. Given the long duration of the mission, the complexity of the payload onboard the Cassini Orbiter and the amount of data gathered on the satellites of Saturn, it would be impossible to describe all the new discoveries made, therefore we will describe only some selected, paramount examples showing how Cassini's data confirmed and extended ground-based observations. In particular we will describe the achievements obtained for the satellites Phoebe, Enceladus and Titan. We will also put these examples in the perspective of the overall evolution of the system, stressing out why the selected satellites are representative of the overall evolution of the Saturn system.

  16. Atmospheric delay modeling for satellite laser altimetry

    MIT - DSpace

    Quinn, Katherine J. (Katherine Jane), 1971-

    2002-01-01

    NASA's Ice, Cloud, and Land Elevation Satellite (ICESat) is a laser altimetry mission with the primary purpose of measuring the mass balance of the ice sheets of Greenland and Antarctica. It will provide 5 years of topography ...

  17. Emerging trends in the satellite industry

    MIT - DSpace

    Salazar, Vagn Knudsen

    2012-01-01

    Risk aversion in the satellite industry has fostered long development cycles and low rates of innovation in the past. Emerging trends in propulsion technology development and spacecraft architecture design could lead to ...

  18. Altimeter sampling characteristics using a single satellite

    University of Kansas - KU ScholarWorks

    Parke, Michael E.; Born, George; Leben, Robert; McLaughlin, Craig A.; Tierney, Craig

    1998-05-15

    Altimetric satellites have characteristic sampling patterns in both space and time based on their repeat period and orbit inclination. Aliased phenomena measured by altimetric measurements can appear as propagating waves with both wavelength...

  19. Quantum interference along satellite-ground channels

    Quantum Physics (arXiv)

    Giuseppe Vallone; Daniele Dequal; Marco Tomasin; Francesco Vedovato; Matteo Schiavon; Vincenza Luceri; Giuseppe Bianco; Paolo Villoresi

    2015-09-25

    Observing quantum interference by moving terminals in Space is a great challenge and a necessary tool for testing Quantum Mechanics in an unexplored scenario. Here we experimentally demonstrate single photon interference due to a superposition of two temporal modes reflected by a rapidly moving satellite thousand kilometers away from the ground station. The relative speed of the satellite induces a varying modulation in the interference pattern. The measurement of the satellite distance in real time by laser ranging allowed us to precisely predict the instantaneous value of the interference phase. We observed the interference patterns with visibility up to 67% with three different satellites. Our results pave the way for quantum communication and tests of Quantum Mechanics and General Relativity.

  20. Anisotropies in the Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Dennis Zaritsky; Rodney Smith; Carlos S. Frenk; Simon D. M. White

    1996-11-26

    We find that satellites of isolated disk galaxies at projected radii between 300 and 500 kpc are distributed asymmetrically about the parent galaxy and aligned preferentially with the disk minor axis. The dynamical timescale at these radii is sufficiently long that the shape of this distribution must reflect the formation history of the outer halo rather than its internal evolution. We also find that the orbital angular momenta of satellites at projected major axis distances of $\\ltsim$ 200 kpc tend to align with that of the central disk. These results demonstrate that satellites are dynamically related to their primary galaxy. Satellites drawn from current simulations of hierarchical galaxy formation exhibit neither the systematic alignment nor the net rotation with the central disk that we find in the data.

  1. Dynamics and control of electromagnetic satellite formations

    MIT - DSpace

    Ahsun, Umair, 1972-

    2007-01-01

    Satellite formation flying is an enabling technology for many space missions, especially for space-based telescopes. Usually there is a tight formation-keeping requirement that may need constant expenditure of fuel or at ...

  2. The Formation of Pluto's Low Mass Satellites

    CERN Preprints

    Kenyon, Scott J

    2013-01-01

    Motivated by the New Horizons mission, we consider how Pluto's small satellites -- currently P5, Nix, P4, and Hydra -- grow in debris from the giant impact that forms the Pluto-Charon binary or in solid material captured from the protoplanetary debris disk. If the satellites have masses close to their minimum masses, our analysis suggests that capture of material into a circumplanetary or circumbinary debris disk is a viable mechanism for satellite formation. If the satellites are more massive, they probably form in debris from the giant impact. After the impact, Pluto and Charon accrete some of the debris and eject the rest from the binary orbit. During the ejection, high velocity collisions among debris particles produce a collisional cascade, leading to the ejection of some debris from the system and enabling the remaining debris particles to find stable orbits around the binary. Our numerical simulations of viscous diffusion, coagulation, and migration show that collisional evolution within a ring or disk...

  3. On the Secular Behavior of Irregular Satellites

    CERN Preprints

    Cuk, Matija

    2004-01-01

    Although analytical studies on the secular motion of the irregular satellites have been published recently, these theories have not yet been satisfactorily reconciled with the results of direct numerical integrations. These discrepancies occur because in secular theories the disturbing function is averaged over orbital motions, whereas instead one should take into account some large periodic terms, most notably the so-called ``evection''. We demonstrate that such terms can be incorporated into the Kozai formalism, and that our synthetic approach produces much better agreement with results from symplectic integrations. Using this method, we plot the locations of secular resonances in the orbital-element space, and we note that the distribution of irregular satellite clusters appears to be non-random. We find that the large majority of irregular-satellite groups cluster close to the secular resonances, with several objects having practically stationary pericenters. None of the largest satellites belong to this ...

  4. Simulation Methodologies for Satellite Solar Array Dynamics 

    Texas A&M University - TxSpace

    Mohsenizadeh, Navid

    2010-07-16

    The purpose of the present thesis is to furnish diverse studies on the dynamic response of satellite solar arrays. The term flexible structure or, briefly, structure has different interpretations and definitions, depending on source...

  5. Resource management for advanced transmission antenna satellites

    MIT - DSpace

    Chan, Vincent W. S.

    In satellite communications, narrow spotbeams can provide high power and data rates to the desired location while reducing spatial interference. Advanced transmission antenna technology is critical to generate and switch ...

  6. Synthetic Aperture Radar Interferometry with 3 satellites

    MIT - DSpace

    Wong, Wallace D. (Wallace Dazheng)

    2005-01-01

    Our study investigates interferometric SAR (InSAR) post-processing height retrieval techniques. We explore the possible improvements by adding a third satellite to the two already in orbit, and examine some potential uses ...

  7. The Anisotropic Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Jeremy Bailin; Chris Power; Peder Norberg; Dennis Zaritsky; Brad K. Gibson

    2008-08-12

    We identify satellites of isolated galaxies in SDSS and examine their angular distribution. Using mock catalogues generated from cosmological N-body simulations, we demonstrate that the selection criteria used to select isolated galaxies and their satellites must be very strict in order to correctly identify systems in which the primary galaxy dominates its environment. The criteria used in many previous studies instead select predominantly group members. We refine a set of selection criteria for which the group contamination is estimated to be less than 7% and present a catalogue of the resulting sample. The angular distribution of satellites about their host is biased towards the major axes for spheroidal galaxies and probably also for red disc galaxies, but is isotropic for blue disc galaxies, i.e. it is the colour of the host that determines the distribution of its satellites rather than its morphology. The similar anisotropy measured in this study as in studies that were dominated by groups implies that group-specific processes are not responsible for the angular distribution. Satellites that are most likely to have been recently accreted show a tendancy to lie along the same axis as the surrounding large scale structure. The orientations of isolated early and intermediate-type galaxies also align with the surrounding large scale structures. We discuss the origin of the anisotropic satellite distribution and consider the implications of our results, critically assessing the respective roles played by the orientation of the visible galaxy within its dark matter halo; anisotropic accretion of satellites from the larger scale environment; and the biased nature of satellites as tracers of the underlying dark matter subhalo population. (Abridged)

  8. MODEL CHECKING SATELLITE OPERATIONAL PROCEDURES Federico Cavaliere1

    Computer Technologies and Information Sciences Websites

    Tronci, Enrico

    Motivations When orbiting, satellites are controlled from the ground by means of satellite Operational ProMODEL CHECKING SATELLITE OPERATIONAL PROCEDURES Federico Cavaliere1 , Federico Mari2 , Igor Melatti/ESTEC, Keplerlaan 1, PO Box 299, 2200AG Noordwijk, The Netherlands, Email: Yuri.Yushtein@esa.int ABSTRACT Satellite

  9. Using Internet nodes and routers onboard satellites W. Ivancic,

    Engineering Websites

    Wood, Lloyd

    Using Internet nodes and routers onboard satellites L. Wood,@ W. Ivancic, D. Hodgson,+* E. Miller router in Low Earth Orbit (CLEO) onboard a small satellite is one step towards extending the terrestrial onboard the UK-DMC disaster monitoring constellation satellite built by Surrey Satellite Technology Ltd

  10. SAMISCTM/MJFF Satellite Meeting 22 February/S Murphy

    Mathematics Websites

    Murphy, Susan A.

    SAMISCTM/MJFF Satellite Meeting 22 February/S Murphy ISCTM/MJFF Satellite Meeting 22 February of AIDS are a form of adaptive txt strategy Individualized interventions #12;SAMISCTM/MJFF Satellite Meeting 22 February/S Murphy ISCTM/MJFF Satellite Meeting 22 February/S Murphy 2 2 Outline · Why Adaptive

  11. istruzioni di montaggio Montiamo insieme il satellite Agile!

    Physics Websites

    manuale istruzioni di montaggio Montiamo insieme il satellite Agile! ( preparazione dei pezzi: 30 minuti - tempo di montaggio: 1 ora circa ) ecco come apparirà il satellite una volta assemblate tutte le satellite. incolla i due sensori stellari laterali del satellite dopo averli piegati con cura #12;manuale

  12. Studying the Ocean CIOSSCooperative Institute for Oceanographic Satellite Studies

    Geosciences Websites

    Kurapov, Alexander

    Studying the Ocean from Space CIOSSCooperative Institute for Oceanographic Satellite Studies #12;CIOSSCooperative Institute for Oceanographic Satellite Stud-What CIOSS Does CIOSS research helps develop our present and past satellites and helping plan future satellite sensors. CIOSS performs research that helps

  13. 1. INTRODUCTION Satellite Doppler navigation, developed between 1957

    Engineering Websites

    Levanon, Nadav

    1. INTRODUCTION Satellite Doppler navigation, developed between 1957 Theoretical Bounds on and 1963. At Random Erro rs i n Satellite least three different satellite systems provide Doppler navigation: 1) the U, geodesy and surveying; 2) the French ARGOS system, on board the U.S. TIROS satellites, which is used

  14. Using the ARPS Satellite Data Remapper Keith Brewster

    Geosciences Websites

    Droegemeier, Kelvin K.

    Using the ARPS Satellite Data Remapper Keith Brewster Center for Analysis and Prediction of Storms satellite data in the ARPS data analysis system (ADAS), it is necessary to remap the observed McIDAS GVAR AREA file satellite data from the satellite-observed pixels to the ARPS grid. 2.Usage makearps mci2arps

  15. A Satellite Mission Control System Brian Schmidt Hermansen

    Mathematics Websites

    communication with the satellite and the Ground Station is the tracking and maintaining of the communication to and then use to communication with a given satellite. This means that one can service more than one satelliteA Satellite Mission Control System Brian Schmidt Hermansen Kongens Lyngby 2006 IMM­THESIS­2006

  16. A Satellite Mission Control System Brian Schmidt Hermansen

    Mathematics Websites

    communication with the satellite and the Ground Station is the tracking and maintaining of the communication to and then use to communication with a given satellite. This means that one can service more than one satelliteA Satellite Mission Control System Brian Schmidt Hermansen Kongens Lyngby 2006 IMM-THESIS-2006

  17. Satellites and Haloes of Dwarf Galaxies

    CERN Preprints

    Sales, Laura V; White, Simon D M; Navarro, Julio F

    2012-01-01

    We study the abundance of satellite galaxies as a function of primary stellar mass using the SDSS/DR7 spectroscopic catalogue. In contrast with previous studies, which focussed mainly on bright primaries, our central galaxies span a wide range of stellar mass, 10^7.5 < M_*^pri/M_sun < 10^11, from dwarfs to central cluster galaxies. Our analysis confirms that the average number of satellites around bright primaries, when expressed in terms of satellite-to-primary stellar mass ratio (m_*^sat/M_*^pri), is a strong function of M_*^pri. On the other hand, satellite abundance is largely independent of primary mass for dwarf primaries (M_*^pri<10^10 M_sun). These results are consistent with galaxy formation models in the LCDM scenario. We find excellent agreement between SDSS data and semi-analytic mock galaxy catalogues constructed from the Millennium-II Simulation. Satellite galaxies trace dark matter substructure in LCDM, so satellite abundance reflects the dependence on halo mass, M_200, of both substru...

  18. Measuring Mass Loss Rates from Galactic Satellites

    Astrophysics (arXiv)

    Kathryn V. Johnston; Steinn Sigurdsson; Lars Hernquist

    1998-05-21

    We present the results of a study that uses numerical simulations to interpret observations of tidally disturbed satellites around the Milky Way. When analysing the simulations from the viewpoint of an observer, we find a break in the slope of the star count and velocity dispersion profiles in our models at the location where unbound stars dominate. We conclude that `extra-tidal' stars and enhanced velocity dispersions observed in the outskirts of Galactic satellites are due to contamination by stellar debris from the tidal interaction with the Milky Way. However, a significant bound population can exist beyond the break radius and we argue that it should not be identified with the tidal radius of the satellite. We also develop and test a method for determining the mass loss rate from a Galactic satellite using its extra-tidal population. We apply this method to observations of globular clusters and dwarf spheroidal satellites of the Milky Way, and conclude that a significant fraction of both satellite systems are likely be destroyed within the next Hubble time. Finally, we demonstrate that this mass loss estimate allows us to place some limits on the initial mass function (IMF) of stars in a cluster from the radial dependence of its present day mass function (PDMF).

  19. Formation and evolution of Pluto's small satellites

    CERN Preprints

    Walsh, Kevin J

    2015-01-01

    Pluto's system of 5 known satellites are in a puzzling orbital configuration. Each of the four small satellites are on low-eccentricity and low-inclination orbits situated near a mean motion resonance with the largest satellite Charon. The Pluto-Charon binary likely formed as a result of a giant impact and so the simplest explanation for the small satellites is that they accreted from debris of that collision. The Pluto-Charon binary has evolved outward since its formation due to tidal forces, which drove them into their current doubly synchronous state. Meanwhile, leftover debris from the formation of Charon was not initially distant enough from Pluto-Charon to explain the orbits of the current small satellites. The outstanding problems of the system are the movement of debris outward and the small satellites location near mean motion resonances with Charon. This work explores the dynamical behavior of collisionally interacting debris orbiting the Pluto-Charon system. While this work specifically tests initi...

  20. Satellite Systems around Galaxies in Hydrodynamic Simulations

    CERN Preprints

    Libeskind, N I; Frenk, C S; Okamoto, T; Jenkins, A; Libeskind, Noam I; Cole, Shaun; Frenk, Carlos S; Okamoto, Takashi; Jenkins, Adrian

    2006-01-01

    We investigate the properties of satellite galaxies formed in N-body/SPH simulations of galaxy formation in the $\\Lambda$CDM cosmology. The simulations include the main physical effects thought to be important in galaxy formation and, in several cases, produce realistic spiral discs. In total, a sample of 9 galaxies of luminosity comparable to the Milky Way was obtained. At magnitudes brighter than the resolution limit, $M_V=-12$, the luminosity function of the satellite galaxies in the simulations is in excellent agreement with data for the Local Group. The radial number density profile of the model satellites, as well as their gas fractions also match observations very well. In agreement with previous N-body studies, we find that the satellites tend to be distributed in highly flattened configurations whose major axis is aligned with the major axis of the (generally triaxial) dark halo. In 2 out of 3 systems with sufficiently large satellite populations, the satellite system is nearly perpendicular to the p...

  1. Star Formation in Satellite Galaxies

    Astrophysics (arXiv)

    C. M. Gutierrez; M. S. Alonso; J. G. Funes; M. B. Ribeiro

    2006-04-14

    We present narrow-band observations of the H$\\alpha$ emission in a sample of 31 satellite orbiting isolated giant spiral galaxies. The sample studied spans the range $-19

  2. History of NOAA Satellite Programs--Updated June 2011 Page 1 History of the NOAA Satellite Program

    Geosciences Websites

    History of NOAA Satellite Programs--Updated June 2011 Page 1 History of the NOAA Satellite Program Gary Davis NOAA Satellite and Information Service 1335 East-West Highway, Silver Spring, Maryland, 20910, USA www.osd.noaa.gov Abstract For more than 50 years, NOAA's environmental satellites have been

  3. Why satellite networking often isn't really satellite networking, and what can be done about it

    Engineering Websites

    Wood, Lloyd

    LECTURE Why satellite networking often isn't really satellite networking, and what can be done about it: moving satellites towards a fuller networking role. Lloyd Wood Global Defense and Space Group, Cisco Systems Abstract Networking via satellites is currently done by a range of separate, non

  4. Where are the missing galactic satellites?

    Astrophysics (arXiv)

    Anatoly A. Klypin; Andrey V. Kravtsov; Octavio Valenzuela; Francisco Prada

    1999-01-21

    Using published data, we have compiled the circular velocity (Vc) distribution function (VDF) of galaxy satellites in the Local Group. We find that within the volumes of radius of 570 kpc (400/h kpc for h=0.7) centered on the Milky Way and Andromeda, the average VDF is roughly approximated as n(>Vc)~ 45(Vc/10 km/s)^{-1} h^3 Mpc^{-3} for Vc in the range ~10-70 km/s. The observed VDF is compared with results of high-resolution cosmological simulations. We find that the VDF in models is very different from the observed one: n(>Vc)~1200(Vc/10 km/s)^{-2.75}h^3 Mpc^{-3}. Cosmological models thus predict that a halo of the size of our Galaxy should have about 50 dark matter satellites with circular velocity >20 km/s and mass >3x10^8/h Msun within a 570 kpc radius. This number is significantly higher than the approximate dozen satellites actually observed around our Galaxy. The observed and predicted VDFs cross at ~50 km/s, indicating that the predicted abundance of satellites with Vc> 50 km/s is in reasonably good agreement with observations. We conclude, therefore, that unless a large fraction of the Local Group satellites has been missed in observations, there is a dramatic discrepancy between observations and hierarchical models, regardless of the model parameters. We discuss several possible explanations for this discrepancy including identification of some satellites with the High Velocity Clouds observed in the Local Group, and the existence of dark satellites that failed to accrete gas and form stars due either to the expulsion of gas in the supernovae-driven winds or to gas heating by the intergalactic ionizing background. (Abridged)

  5. The satellite distribution of M31

    Astrophysics (arXiv)

    Alan McConnachie; Mike Irwin

    2005-10-21

    (Abridged) The spatial distribution of the Galactic satellite system plays an important role in Galactic dynamics and cosmology, where its successful reproduction is a key test of simulations of galaxy halo formation. Here, we examine its representative nature by conducting an analysis of the 3-dimensional spatial distribution of the M31 subgroup of galaxies. We begin by a discussion of distance estimates and incompleteness concerns, before revisiting the question of membership of the M31 subgroup. Comparison of the distribution of M31 and Galactic satellites relative to the galactic disks suggests that the Galactic system is probably modestly incomplete at low latitudes by ~20%. We find that the radial distribution of satellites around M31 is more extended than the Galactic subgroup; 50% of the Galactic satellites are found within ~100kpc of the Galaxy, compared to ~200kpc for M31. We search for ``ghostly streams'' of satellites around M31, in the same way others have done for the Galaxy, and find several. The lack of M31-centric kinematic data, however, means we are unable to probe whether these streams represent real physical associations. Finally, we find that the M31 satellites are asymmetrically distributed with respect to our line-of-sight to this object, so that the majority of its satellites are on its near side with respect to our line-of-sight. We quantify this result and find it to be significant at the ~3 sigma level. Until such time as a satisfactory explanation for this finding is presented, our results warn against treating the M31 subgroup as complete, unbiased and relaxed.

  6. January 30, 2003 1 Center for Satellite and HybridCenter for Satellite and Hybrid

    Computer Technologies and Information Sciences Websites

    Gligor, Virgil D.

    administration of shared applications · Joint Administration Services ­ Joint administration requirements: JointJanuary 30, 2003 1 Center for Satellite and HybridCenter for Satellite and Hybrid Communication NetworksCommunication Networks Integrated Security Services for DynamicIntegrated Security Services

  7. Proposed Nomenclature for Surface Features on Pluto and Its Satellites and Names for Newly Discovered Satellites

    CERN Preprints

    Mamajek, Eric E; Cameron, David A; Olmedo, Manuel; Fogerty, Shane; Franklin, Eric; Lambrides, Erini; Hasan, Imran; Sarkis, Richard E; Thorndike, Stephen; Nordhaus, Jason

    2015-01-01

    In anticipation of the July 2015 flyby of the Pluto system by NASA's New Horizons mission, we propose naming conventions and example names for surface features on Pluto and its satellites (Charon, Nix, Hydra, Kerberos, Styx) and names for newly discovered satellites.

  8. Notes on the Missing Satellites Problem

    CERN Preprints

    Bullock, James S

    2010-01-01

    The Missing Satellites Problem (MSP) broadly refers to the overabundance of predicted Cold Dark Matter (CDM) subhalos compared to satellite galaxies known to exist in the Local Group. The most popular interpretation of the MSP is that the smallest dark matter halos in the universe are extremely inefficient at forming stars. The question from that standpoint is to identify the feedback source that makes small halos dark and to identify any obvious mass scale where the truncation in the efficiency of galaxy formation occurs. Among the most exciting developments in near-field cosmology in recent years is the discovery of a new population satellite galaxies orbiting the Milky Way and M31. Wide field, resolved star surveys have more than doubled the dwarf satellite count in less than a decade, revealing a population of ultrafaint galaxies that are less luminous that some star clusters. For the first time, there are empirical reasons to believe that there really are missing satellite galaxies in the Local Group, lu...

  9. On the Secular Behavior of Irregular Satellites

    Astrophysics (arXiv)

    Matija Cuk; Joseph A. Burns

    2004-08-05

    Although analytical studies on the secular motion of the irregular satellites have been published recently, these theories have not yet been satisfactorily reconciled with the results of direct numerical integrations. These discrepancies occur because in secular theories the disturbing function is averaged over orbital motions, whereas instead one should take into account some large periodic terms, most notably the so-called ``evection''. We demonstrate that such terms can be incorporated into the Kozai formalism, and that our synthetic approach produces much better agreement with results from symplectic integrations. Using this method, we plot the locations of secular resonances in the orbital-element space, and we note that the distribution of irregular satellite clusters appears to be non-random. We find that the large majority of irregular-satellite groups cluster close to the secular resonances, with several objects having practically stationary pericenters. None of the largest satellites belong to this class, so we argue that this dichotomy implies that the smaller near-resonant satellites might have been captured differently than the largest irregulars.

  10. Macho Parallaxes From A Single Satellite

    Astrophysics (arXiv)

    Andrew Gould

    1994-08-10

    Massive Compact Objects (Machos) are currently being discovered at substantially higher rates than would be expected from standard models of known stellar populations. To determine whether they are due to non-standard distri- butions of known populations or to a heretofore unknown (`dark') population, one must acquire more information about the individual events. Space-based parallaxes are potentially the best tool for extracting additional information. To leading order, parallax measurements by a single satellite result in a four- fold degeneracy: two possible values of $\\tilde v$ and two possible signs for the component of motion perpendicular to the projected satellite-Earth vector. It had been believed that a second satellite would be required to break this degeneracy. I show that the velocity difference between the satellite and the Earth allows one to partially or totally break the degeneracy using a single satellite. For most Macho events it is possible to measure $\\tilde v$ and $\\tilde r_e$. For some it is also possible to measure $\\Phi$. The proposed Space Infrared Telescope could measure $\\sim 100$ parallaxes per year by applying $\\sim 400\\,$hr of telescope time.

  11. Star Formation and Quenching of Satellite Galaxies

    CERN Preprints

    Lu, Zhankui

    2015-01-01

    We study the quenching of satellite galaxies by gradual depletion of gas due to star formation, by ram-pressure striping and by tidally triggered starburst. Using progenitors constrained by the empirical model of Lu et al., in which outflow loading factor is low, we do not find an over-quenching problem in satellites even if there is no further cold gas supply from the cooling of the halo gas after a galaxy is accreted by its host. Gradual depletion alone predicts a unimodal distribution in specific star formation, in contrast to the bimodal distribution observed, and under-predicts the quenched fraction in low mass halos. Ram-pressure stripping nicely reproduces the bimodal distribution but under-predicts the quenched fraction in low-mass halos. Starbursts in gas-rich satellites triggered by tidal interactions with central galaxies can nicely reproduce the quenched satellite population in low-mass halos, but become unimportant for low-mass satellites in massive halos. The combined processes, together with th...

  12. Quasi-satellite dynamics in formation flight

    CERN Preprints

    Mikkola, Seppo

    2016-01-01

    The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three satellites in low eccentricity near Earth orbits. With the help of weak ion thrusters it is possible to accomplish tandem flight. With ion thrusters it is also possible to mimic many kinds of mutual force laws between the satellites. We found that both a constant repulsive force or an attractive force that decreases with the distance are able to preserve the formation in which the eccentricities cause the actual relative motion and the weak thrusters keep the mean longitude difference small. Initial values are important for the formation flight but very exact adjustment of orbital elements is not important. Simplicity is one of our goals in this study and this result is achieved at least in the way that, when constant force thrusters are used, the satellites only need to detect the...

  13. The dynamics of tidal tails from massive satellites

    CERN Preprints

    Choi, J H; Katz, N; Choi, Jun-Hwan; Weinberg, Martin D.; Katz, Neal

    2007-01-01

    (Abbreviated) We investigate the dynamical mechanisms responsible for producing tidal tails from dwarf satellites using N-body simulations. We identify two important dynamical co-conspirators: 1) the points where the attractive force of the host halo and satellite are balanced do not occur at equal distances from the satellite centre or at the same equipotential value for massive satellites, breaking the morphological symmetry of the leading and trailing tails; and 2) the escaped ejecta in the leading (trailing) tail continues to be decelerated (accelerated) by the satellite's gravity leading to large offsets of the ejecta orbits from the satellite orbit. The effect of the satellite's self gravity decreases only weakly with a decreasing ratio of satellite mass to host halo mass, demonstrating the importance of these effects over a wide range of subhalo masses. Not only will the morphology of the leading and trailing tails for massive satellites be different, but the observed radial velocities of the tails wil...

  14. On Asymmetric Distributions of Satellite Galaxies

    CERN Preprints

    Bowden, A; Belokurov, V

    2014-01-01

    We demonstrate that the asymmetric distribution of M31 satellites cannot be produced by tides from the Milky Way as such effects are too weak. However, loosely bound associations and groups of satellites can fall into larger haloes and give rise to asymmetries. We compute the survival times for such associations. We prove that the survival time is always shortest in Keplerian potentials, and can be ~ 3 times longer in logarithmic potentials. We provide an analytical formula for the dispersal time in terms of the size and velocity dispersion of the infalling structure. We show that, if an association of ~10 dwarfs fell into the M31 halo, its present aspect would be that of an asymmetric disk of satellites. We also discuss the case of cold substructure in the Andromeda II and Ursa Minor dwarfs.

  15. Introducing Relativity in Global Navigation Satellite Systems

    General Relativity & Quantum Cosmology (arXiv)

    J. -F. Pascual-Sanchez

    2006-12-13

    Today, the Global Navigation Satellite Systems, used as global positioning systems, are the GPS and the GLONASS. They are based on a Newtonian model and hence they are only operative when several relativistic effects are taken into account. The most important relativistic effects (to order 1/c^2) are: the Einstein gravitational blue shift effect of the satellite clock frequency (Equivalence Principle of General Relativity) and the Doppler red shift of second order, due to the motion of the satellite (Special Relativity). On the other hand, in a few years the Galileo system will be built, copying the GPS system unless an alternative project is designed. In this work, it will be also shown that the SYPOR project, using fully relativistic concepts, is an alternative to a mere copy of the GPS system. According to this project, the Galileo system would be exact and there would be no need for relativistic corrections.

  16. Dwarf satellite galaxies in the modified dynamics

    Astrophysics (arXiv)

    Rafael Brada; Mordehai Milgrom

    2000-05-11

    In the modified dynamics (MOND) the inner workings of dwarf satellites can be greatly affected by their mother galaxy-over and beyond its tidal effects. Because of MOND's nonlinearity a system's internal dynamics can be altered by an external field in which it is immersed (even when this field, by itself, is constant in space). As a result, the size and velocity dispersion of the satellite vary as the external field varies along its orbit. A notable outcome of this is a substantial increase in the dwarf's vulnerability to eventual tidal disruption-rather higher than Newtonian dynamics (with a dark-matter halo) would lead us to expect for a satellite with given observed parameters.

  17. Modeling the Milky-Way Satellite galaxies

    Astrophysics (arXiv)

    X. Kang

    2008-06-19

    We revisit the Milky Way satellite problem using a semi-analytical model of galaxy formation and compare the predicted luminosity function to recent result from the SDSS. With cosmic photoionization, the luminosity function can be brought into broad agreement with the data between $-15< M_{V} <-2$. This improvement over previous semi-analytical model results (e.g., Benson et al.2002) is from our adoption of improved models for galaxy merger history and galaxy merging time-scales. The very faint satellites ($M_{v} > -5$) formed in halos with virial temperature over $10^{4}K$ (mass around $10^{9} M_{\\odot}$ before accretion), but their baryon content are strongly suppressed by photoionization. We model the mass evolution of the subhalos, and compare the predicted mass-to-light ratio with the data. We find that the measured total mass inside the luminous radii of satellites are about 5% of their present total dark matter mass.

  18. Simulating Sinking Satellites with SUPERBOX-10

    CERN Preprints

    Bien, Reinhold; Just, Andreas

    2012-01-01

    SUPERBOX-10 is the successor of SUPERBOX, a particle-mesh code where additional grids and sub-grids are applied to regions of high particle density. Previous limitations have been solved. For instance, the vertical resolution is improved considerably when flattened grids are used. Since the computationally most intensive part is the Fast Fourier Transform, we introduce a parallelised version using the library FFTW, resulting in a speed-up of a few. The new features are tested using a galaxy model consisting of an exponential disc, a bulge and a dark matter halo. We demonstrate that the use of flattened grids efficiently reduces numerical heating. We simulate the merging of disc-bulge-halo galaxies with small spherical satellites. As a result, satellites on orbits with both low eccentricity and inclination heat the disc most efficiently. Moreover, we find that most of the satellite's energy and angular momentum is transfered to the halo.

  19. Satellite Systems around Galaxies in Hydrodynamic Simulations

    Astrophysics (arXiv)

    Noam I Libeskind; Shaun Cole; Carlos S Frenk; Takashi Okamoto; Adrian Jenkins

    2006-07-11

    We investigate the properties of satellite galaxies formed in N-body/SPH simulations of galaxy formation in the $\\Lambda$CDM cosmology. The simulations include the main physical effects thought to be important in galaxy formation and, in several cases, produce realistic spiral discs. In total, a sample of 9 galaxies of luminosity comparable to the Milky Way was obtained. At magnitudes brighter than the resolution limit, $M_V=-12$, the luminosity function of the satellite galaxies in the simulations is in excellent agreement with data for the Local Group. The radial number density profile of the model satellites, as well as their gas fractions also match observations very well. In agreement with previous N-body studies, we find that the satellites tend to be distributed in highly flattened configurations whose major axis is aligned with the major axis of the (generally triaxial) dark halo. In 2 out of 3 systems with sufficiently large satellite populations, the satellite system is nearly perpendicular to the plane of the galactic disc, a configuration analogous to that observed in the Milk Way. The discs themselves are perpendicular to the minor axis of their host halos in the inner parts, and the correlation between the orientation of the galaxy and the shape of the halo persists even out to the virial radius. However, in one case the disc's minor axis ends up, at the virial radius, perpendicular to the minor axis of the halo. The angular momenta of the galaxies and their host halo tend to be well aligned.

  20. Construction of an Electrostatic Energy Analyzer for the EQUARS Scientific Satellite

    Plasma Physics and Fusion Websites

    Construction of an Electrostatic Energy Analyzer for the EQUARS Scientific Satellite The ELISA and Scintillations EQUARS - Equatorial Atmosphere Research SatelliteEQUARS - Equatorial Atmosphere Research Satellite

  1. A relativistic and autonomous navigation satellite system

    General Relativity & Quantum Cosmology (arXiv)

    Pacôme Delva; Andrej Cadez; Uros Kostic; Sante Carloni

    2011-06-17

    A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

  2. A relativistic and autonomous navigation satellite system

    CERN Preprints

    Delva, Pacôme; Kosti?, Uros; Carloni, Sante

    2011-01-01

    A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

  3. On the orbit of the LARES satellite

    General Relativity & Quantum Cosmology (arXiv)

    Ignazio Ciufolini

    2006-09-20

    This paper is motivated by the recent possibility to find an inexpensive launching vehicle for the LARES satellite, however at an altitude much lower than originally planned for the LAGEOS III/LARES satellite. We present here a preliminary error analysis corresponding to a lower, quasi-polar, orbit, in particular we analyze the effect on the LARES node of the Earth's static gravitational field, and in particular of the Earth's even zonal harmonics, the effect of the time dependent Earth's gravitational field, and in particular of the K1 tide, and the effect of particle drag.

  4. International Symposium on Formal Methods 2012 Autonomy in Satellite Systems

    Engineering Websites

    Liberzon, Daniel

    International Symposium on Formal Methods 2012 Autonomy in Satellite Systems · Number of satellites controlled autonomous & complex operations Image courtesy NASA #12;International Symposium on Formal Methods Faculty Fellowship Program (SFFP). Rachel Dudley Iowa State University International Symposium on Formal

  5. Cooperative Institute for Meteorological Satellite Studies University of Wisconsin -Madison

    Geosciences Websites

    Collett Jr., Jeffrey L.

    Cooperative Institute for Meteorological Satellite Studies University of Wisconsin University of Wisconsin #12;Cooperative Institute for Meteorological Satellite Studies University of Wisconsin - Madison In 1979.... #12;Cooperative Institute for Meteorological

  6. ATMOSPHERIC DENSITY ESTIMATION USING SATELLITE PRECISION ORBIT EPHEMERIDES

    University of Kansas - KU ScholarWorks

    Arudra, Anoop Kumar

    2011-04-22

    results in erroneous density values that are not accurate enough to calculate the drag estimates acting on a satellite, thus leading to errors in the prediction of satellite orbits. This research utilized precision orbit ephemerides (POE) data from...

  7. Building technological capability within satellite programs in developing countries

    MIT - DSpace

    Wood, Danielle Renee

    2012-01-01

    Global participation in space activity is growing as satellite technology matures and spreads. Countries in Africa, Asia and Latin America are creating or reinvigorating national satellite programs. These countries are ...

  8. STABILITY OF SATELLITES IN CLOSELY PACKED PLANETARY SYSTEMS

    MIT - DSpace

    Payne, Matthew J.

    We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary systems with tightly packed inner planets (STIPs). We find that the majority ...

  9. Regional Navigation System Using Geosynchronous Satellites and Stratospheric Airships

    Engineering Websites

    Won, Chang-Hee

    - 1 - Regional Navigation System Using Geosynchronous Satellites and Stratospheric Airships Chang navigation system using geosynchronous satellites and stratospheric airships. One important factor in designing a navigation system is dilution of precision. We design a regional navigation system based

  10. INSURED project (INtegrated Satellite UMTS Real Environment Demonstrator)

    Engineering Websites

    Vouyioukas, Demosthenes

    satellite system (IRIDIUM) and a GSM network. The trials carried out with the demonstrator are of paramount; the first pre-operational IRIDIUM satellites are available for experimentation. The INSURED project

  11. Achieving broad access to satellite control research with zero robotics

    MIT - DSpace

    Katz, Jacob G

    2013-01-01

    Since operations began in 2006, the SPHERES facility, including three satellites aboard the International Space Station (ISS), has demonstrated many future satellite technologies in a true microgravity environment and ...

  12. Accounting for Uncertainties of the TRMM Satellite Estimates

    University of California eScholarship Repository

    AghaKouchak, Amir; Nasrollahi, Nasrin; Habib, Emad

    2009-01-01

    uncertainty estimation of satellite rainfall observations inBellerby, T. Satellite rainfall uncertainty estimation usingsatellite precipitation error, a great deal of effort has been made in describing estimation error of radar rainfall

  13. Satellite Observations of Tropospheric Chemistry: Retrievals and Interpretation

    Geosciences Websites

    Martin, Randall

    Satellite Observations of Tropospheric Chemistry: Retrievals and Interpretation A thesis presented;Daniel J. Jacob Randall V. Martin Satellite Observations of Tropospheric Chemistry: Retrievals and Interpretation Abstract This thesis exploits nascent capabilities for observation of tropospheric chemistry from

  14. Satellite Tagging and Cardiac Physiology Reveal Niche

    Environmental Sciences and Ecology Websites

    Block, Barbara A.

    Satellite Tagging and Cardiac Physiology Reveal Niche Expansion in Salmon Sharks Kevin C. Weng,1. Schallert,3 Kenneth J. Goldman,4 Barbara A. Block1 . Shark populations are declining globally, yet to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have

  15. NASA Launches Next-Generation Communications Satellite

    Physics Websites

    Christian, Eric

    NASA Launches Next-Generation Communications Satellite Pg 3 Triumph Over Tragedy: Columbia's Last Mission Pg 6 Goddard Day of Remembrance Pg 9 National Aeronautics and Space Administration www.nasa.gov Volume 9 Issue 1 February 2013 #12;T he first of NASA's three next-generation Tracking and Data Relay

  16. Ocean Surface Currents From Geostationary Satellite SST

    Geosciences Websites

    Kurapov, Alexander

    Ocean Surface Currents From Geostationary Satellite SST -We are implementing and evaluating a feature tracking approach to estimate ocean surface currents. - This approach allows us to estimate in the global ocean where images are available. Uses include search and rescue, monitoring trajectories

  17. Isolated Galaxies and Isolated Satellite Systems

    CERN Preprints

    Ann, H B; Choi, Yun-Young

    2009-01-01

    We search for isolated galaxies using a volume-limited sample of galaxies with 0.02r_{vir,nei} and \\rho <\\bar{\\rho} well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.

  18. The surprising inefficiency of dwarf satellite quenching

    CERN Preprints

    Wheeler, Coral; Cooper, Michael C; Boylan-Kolchin, Mike; Bullock, James S

    2014-01-01

    We study dwarf satellite galaxy quenching using observations from the Geha et al. (2012) NSA/SDSS catalog together with LCDM cosmological simulations to facilitate selection and interpretation. We show that fewer than 30% of dwarfs (M* ~ 10^8.5-10^9.5 Msun) identified as satellites within massive host halos (Mhost ~ 10^12.5-10^14 Msun) are quenched, in spite of the expectation from simulations that half of them should have been accreted more than 6 Gyr ago. We conclude that whatever the action triggering environmental quenching of dwarf satellites, the process must be highly inefficient. We investigate a series of simple, one-parameter quenching models in order understand what is required to explain the low quenched fraction and conclude that either the quenching timescale is very long (> 9.5 Gyr, a "slow starvation" scenario) or that the environmental trigger is not well matched to accretion within the virial volume. We discuss these results in light of the fact that most of the low mass dwarf satellites in ...

  19. SATELLITE LOCATIONS University of California Berkeley

    Chemistry Websites

    Iglesia, Enrique

    SATELLITE LOCATIONS University of California Berkeley 2222 Bancroft Way, 3rd Floor Berkeley CA (510 including academic success, life management, career and life planning and personal growth and development counseling · Workshops (ex. stress managament, career planning) · Evaluation and Follow up for psychiatric

  20. Modern Digital Satellite Television: How It Works

    Computer Technologies and Information Sciences Websites

    Valenti, Matthew C.

    #12;Outline 1 Satellite Television Standards 2 DVB-S2 Modulation 3 LDPC Coding 4 Constellation Shaping Television Standards 2 DVB-S2 Modulation 3 LDPC Coding 4 Constellation Shaping 5 Conclusion M.C. Valenti-S2 Modulation 3 LDPC Coding 4 Constellation Shaping 5 Conclusion M.C. Valenti ( Lane Department

  1. National Environmental Satellite, Data, and Information Service

    Geosciences Websites

    satellite observations and integrated products and to provide long-term stewardship for global environmental weather ·Primary input for numerical prediction models ·Real-time images/products Resilient Coastal information for predictive environmental and atmospheric modeling systems and space-based distress alert

  2. An Algorithm to Estimate Satellite Rainfall Rate

    Geosciences Websites

    Gilbes, Fernando

    . · The projection algorithm was used to detect cloud rainy pixels and the time a spatial lags model was used satellite imagery. #12;Methodology #12;Detection algorithm: Pixel Classification · The calibration data algorithm was implemented over Puerto Rico and it was found that some warm clouds were not detected

  3. Thursday, March 16, 2006 THE GALILEAN SATELLITES

    Physics Websites

    Rathbun, Julie A.

    center. Preliminary results indicate that magma will pond at shallow depths under a volatile layer. 9 distribution within a convective ice shell on Europa. Our simulations demonstrate that the grain size. C. * McKinnon W. B. Convection in Icy Satellites with Self-Consistent Grain Size [#2130] Ice grain

  4. Signal Deformations On Nominally Healthy GPS Satellites

    Engineering Websites

    Stanford University

    Signal Deformations On Nominally Healthy GPS Satellites Alexander M. Mitelman, R. Eric Phelts Engineering from Stanford University in 1995. His research is focused on local area differential GPS de- sign University, Sweden, and then as Research Associate with the GPS Laboratory at Stanford University. Currently

  5. The chemical composition of the Galileian satellites

    Astrophysics (arXiv)

    V. Celebonovic

    1998-07-20

    Using the semiclassical theory of dense matter proposed by P.Savic and R.Kasanin,the mean molecular masses of the Galilean satellites of Jupiter are determined.The calculated values are fitted by plausible combinations of chemical elements,and the results are in good agreement with the observations by "Galileo".Possible cosmogonical explanations are briefly discussed.

  6. Asymmetric Warfare: M31 and its Satellites

    CERN Preprints

    Fardal, Mark A

    2009-01-01

    Photometric surveys of M31's halo vividly illustrate the wreckage caused by hierarchical galaxy formation. Several of M31's satellites are being disrupted by M31's tidal field, among them M33 and And I, while other tidal structures are the corpses of satellites already destroyed. The extent to which M31's satellites have left battle scars upon it is unknown; to answer this we need accurate orbits and masses of the perturbers. I focus here on M31's 150-kpc-long Giant Southern Stream (GSS) as an example of how these can be determined even in the absence of a visible progenitor. Comparing N-body models to photometric and spectroscopic data, I find this stream resulted from the disruption of a large satellite galaxy by a close passage about 750 Myr ago. The GSS is connected to several other debris structures in M31's halo. Bayesian sampling of the simulations estimates the progenitor's initial mass as log(Mstar/Msun) = 9.5 +- 0.2, showing it was one of the most massive Local Group galaxies until quite recently. T...

  7. PERFORMANCE EVALUATION OF NEMO IN SATELLITE NETWORKS

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    of multiple IP-enabled devices on- board a Low Earth Orbit satellite (a mobile network on-board). NEMO. In addition, NEMO protocols can provide continuous connectivity at upper layers using nested NEMO (a mobile shows continuity of connections at upper layers and performance superiority of Saratoga to TCP for NEMO

  8. Euler deconvolution in satellite geodesy Matthias Roth

    Geosciences Websites

    Stuttgart, Universität

    . (2000)). The satellite mission GOCE (Gravity field and steady- state Ocean Circulation Explorer of superposition states that we can consider Earth being assembled by numerous point masses. One of those point (LS) method (Gauss-Markov model) = A + e = ^ = (AT A)-1 AT Each window position delivers one

  9. Satellite Remote Sensing SIO 135/SIO 236

    Geosciences Websites

    Sandwell, David T.

    1 Satellite Remote Sensing SIO 135/SIO 236 Electromagnetic Radiation and Polarization #12;Electromagnetic Radiation Models «To understand the interaction that the EMR undergoes before it reaches by the equation speed of light = frequency x wavelength Electromagnetic waves #12;Wave Model of Electromagnetic

  10. Dynamics and real-time optimal control of satellite attitude and satellite formation systems 

    Texas A&M University - TxSpace

    Yan, Hui

    2006-10-30

    . Three-axis magnetic attitude stabilization is achieved by using a pseudospectral control law via the receding horizon control for satellites in eccentric low Earth orbits. The solutions from the pseudospectral control law are in excellent agreement...

  11. On stacked central configuration of the planar coorbital satellites problem

    CERN Preprints

    Oliveira, Allyson

    2011-01-01

    In this work we look for central configurations of the planar 1 + n body problem such that, after the addition of one or two satellites, we have a new planar central configuration. We determine all such configurations in two cases: the first, the addition of two satellites considering that all satellites have equal infinitesimal masses and the second case where one satellite is added but the infinitesimal masses are not necessarily equal.

  12. Formal Specification and Quantitative Analysis of a Constellation of Navigation Satellites

    Computer Technologies and Information Sciences Websites

    Miller, Alice

    Formal Specification and Quantitative Analysis of a Constellation of Navigation Satellites a single satellite and a navigation satellite constellation and logical specification of their reliability in satellite constellations Correspondence to: Yu Lu, School of Computing Science, University of Glasgow

  13. FY 2010 NOAA BUDGET HIGHLIGHTS (National Environmental Satellite, Data, and Information Service)

    Geosciences Websites

    FY 2010 NOAA BUDGET HIGHLIGHTS Satellites (National Environmental Satellite, Data, and Information Service) The National Environmental Satellite, Data, and Information Service (NESDIS) requests $1,428.6M NOAA's satellite acquisition programs, procures imagery for critical navigational products

  14. Cognitive Satellite Terrestrial Radios Sithamparanathan Kandeepan, Luca De Nardis, Maria-Gabriella Di Benedetto,

    Engineering Websites

    Di Benedetto, Maria-Gabriella

    Cognitive Satellite Terrestrial Radios § Sithamparanathan Kandeepan, Luca De Nardis, Maria the concept of cognitive satellite terrestrial radios (CSTR) for hybrid satellite-terrestrial systems (HSTS of the radio spectrum. The future satellite ground terminals therefore need to integrate and co

  15. Programmable Active Networking supporting Next Generation Multimedia Services in Satellite Networks

    Computer Technologies and Information Sciences Websites

    Bhatti, Saleem N.

    1 Programmable Active Networking supporting Next Generation Multimedia Services in Satellite the space segment of satellite networks could take benefit. The first commercial regenerative satellite routing functionality will become available. However, from the design of these satellite systems

  16. On the Life and Death of Satellite Haloes

    Astrophysics (arXiv)

    Giuliano Taffoni; Lucio Mayer; Monica Colpi; Fabio Governato

    2003-01-14

    We study the evolution of dark matter satellites orbiting inside more massive haloes using semi-analytical tools coupled with high-resolution N-Body simulations. We select initial satellite sizes, masses, orbital energies, and eccentricities as predicted by hierarchical models of structure formation. Both the satellite and the main halo are described by a Navarro, Frenk & White density profile with various concentrations.

  17. On the perturbations on satellites probing General Relativity

    General Relativity & Quantum Cosmology (arXiv)

    S. Sargsyan; G. Yegorian; S. Mirzoyan

    2013-12-19

    Non-gravitational Yarkovsky-Rubincam effect for LAGEOS and LAGEOS 2 satellites used to probe General Relativity has been revealed by means of the Kolmogorov analysis of their perturbations. We present the method and its efficiency at modeling of generated systems with properties expected at the satellite laser ranging measurements and then at satellite residual data analysis.

  18. Performance Modelling of TCP Enhancements in Terrestrial-Satellite Hybrid

    Engineering Websites

    Roy, Sumit

    1 Performance Modelling of TCP Enhancements in Terrestrial-Satellite Hybrid Networks Jing Zhu Abstract In this paper, we focus on the performance of TCP enhancements for a hybrid terrestrial- satellite, fewer work are related to TCP over satellite links, which is the objective of this paper. We studied two

  19. A Satellite Survey of Cloud Cover and Water Vapour

    Physics Websites

    5 2.1 Satellite data 5 2.2 Topography data 6 2.3 Meteorological data 6 2.3.1 Rawinsonde data 7 2 is logistically impossible. Meteorological satellites provide a consistent measurement of cloud cover and water, most of the meteorological satellites observing different areas of the globe are equipped with similar

  20. Secure Floating-Point Arithmetic and Private Satellite Collision Analysis

    Multidisciplinary Databases and Resources Websites

    International Association for Cryptologic Research (IACR)

    Secure Floating-Point Arithmetic and Private Satellite Collision Analysis Liina Kamm1,2 and Jan of a collision between two satellites. For this purpose, we first describe basic floating-point arithmetic these primitives, we implement a satellite conjunction analysis algorithm and give benchmark results

  1. On-Demand Routing in LEO Satellite Systems Stylianos Karapantazis

    Computer Technologies and Information Sciences Websites

    Papapetrou, Evaggelos

    On-Demand Routing in LEO Satellite Systems Stylianos Karapantazis Aristotle University) satellite systems is proposed and evaluated. This protocol can be viewed as a variant of the well-known ad by the characteristics of LEO satellite systems' topology. The LAOR protocol is assessed for different link-cost metrics

  2. FOP Is a Centriolar Satellite Protein Involved in Ciliogenesis

    Biology and Medicine Websites

    Stearns, Tim

    FOP Is a Centriolar Satellite Protein Involved in Ciliogenesis Joanna Y. Lee1 , Tim Stearns1,2 * 1 satellites are proteinaceous granules that are often clustered around the centrosome. Although centriolar satellites have been implicated in protein trafficking in relation to the centrosome and cilium, the details

  3. Irregular Satellites of the Planets: Products of Capture

    Physics Websites

    Jewitt, David C.

    Irregular Satellites of the Planets: Products of Capture in the Early Solar System David Jewitt satellites, characterized by large, highly eccentric and/or inclined orbits that are distinct from the nearly circular, uninclined orbits of the regular satellites. This difference can be traced directly to different

  4. A Review of Impending Small Satellite Formation Flying Missions

    Engineering Websites

    Chung, Soon-Jo

    A Review of Impending Small Satellite Formation Flying Missions Saptarshi Bandyopadhyay , Giri P of Technology, Pasadena, California 91109, USA Small satellites, like popular nanosatellite platforms called. This paper presents a review of thirty-nine missions, using multiple small satellites, in various stages

  5. Virtual Genus of Satellite Links Daniel S. Silver

    Mathematics Websites

    Williams, Susan

    Virtual Genus of Satellite Links Daniel S. Silver Susan G. Williams Department of Mathematics and Statistics, University of South Alabama February 10, 2013 Abstract The virtual genus of a virtual satellite. Then ~= ~1 · · · ~d is a satellite link of with com- panion . It is clear that the virtual genus

  6. TOWARDS NAVIGATION BASED ON 120 SATELLITES: ANALYZING THE NEW SIGNALS

    Engineering Websites

    Stanford University

    TOWARDS NAVIGATION BASED ON 120 SATELLITES: ANALYZING THE NEW SIGNALS A DISSERTATION SUBMITTED Satellite Systems (GNSS) are experiencing a new era. The US Global Positioning System (GPS) now serves over is developing the Galileo system that promises to place 30 more satellite in medium Earth orbit

  7. Optimal Scheduling for Servicing Multiple Satellites in a Circular Constellation

    Engineering Websites

    Tsiotras, Panagiotis

    Optimal Scheduling for Servicing Multiple Satellites in a Circular Constellation Haijun Shen the scheduling of servicing multiple satellites in a circular orbit. Specifically, one servicing spacecraft (SSc) is considered to be initially on the circular orbit of the satellites to be serviced. The SSc then rendezvous

  8. Evaluation of the Route Optimization for NEMO in Satellite Networks

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    Evaluation of the Route Optimization for NEMO in Satellite Networks Abu Zafar M. Shahriar,atiq}@ou.edu William D. Ivancic Satellite Networks and Architectures Branch NASA Glenn Research Center Cleveland, OH architecture that has been proposed for satellite networks to manage the mobility of Internet Protocol

  9. Image deblurring, Spectrum Interpolation and Application to Satellite Imaging

    Mathematics Websites

    Malgouyres, François

    Image deblurring, Spectrum Interpolation and Application to Satellite Imaging Sylvain Durand of satellite SPOT images. Abstract Cet article porte sur deux m'ethodes compl'ementaires de d'econvolution d images satellites SPOT. 1 Introduction This paper deals with two complementary methods in image

  10. SATELLITES OF LEGENDRIAN KNOTS AND REPRESENTATIONS OF THE CHEKANOVELIASHBERG

    Mathematics Websites

    Ng, Lenny

    SATELLITES OF LEGENDRIAN KNOTS AND REPRESENTATIONS OF THE CHEKANOV­ELIASHBERG ALGEBRA LENHARD NG AND DAN RUTHERFORD Abstract. We study satellites of Legendrian knots in R3 and their relation has finite-dimensional representations if and only if there exist certain rulings of satellites

  11. KEY MANAGEMENT FOR SECURE MULTICAST IN HYBRID SATELLITE NETWORKS

    Engineering Websites

    Baras, John S.

    KEY MANAGEMENT FOR SECURE MULTICAST IN HYBRID SATELLITE NETWORKS Ayan Roy-Chowdhury Department This paper proposes a design for key management for secure multicast in hy- brid satellite networks. Communication satellites offer an efficient way to ex- tend IP multicast services for groups in wide

  12. A SIMULATION STUDY OF TCP PERFORMANCE OVER SATELLITE CHANNELS

    Engineering Websites

    1 A SIMULATION STUDY OF TCP PERFORMANCE OVER SATELLITE CHANNELS G. Neglia, V. Mancuso, F. Saitta, I, Italy ABSTRACT This document is mainly about the influence of protocols on the performance of Satellite Communication. It is widely recognized that satellite communications are affected by some peculiar problems

  13. MULTIPLICITY OF COMPLEX HYPERSURFACE SINGULARITIES, ROUCHE SATELLITES AND ZARISKI'S PROBLEM

    Mathematics Websites

    Gasparim, Elizabeth

    MULTIPLICITY OF COMPLEX HYPERSURFACE SINGULARITIES, ROUCH´E SATELLITES AND ZARISKI'S PROBLEM singularit´es d'hypersurfaces complexes, satellites de Rouch´e et probl`eme de Zariski. Soient f, g : (Cn , 0 such an inequality a Rouch´e inequality and we say that g is a Rouch´e satellite of f . In Section 3, we apply

  14. Virtual Genus of Satellite Links Daniel S. Silver

    Mathematics Websites

    Silver, Dan

    Virtual Genus of Satellite Links Daniel S. Silver Susan G. Williams Department of Mathematics and Statistics, University of South Alabama January 21, 2013 Abstract The virtual genus of a virtual satellite. Then ~= ~1 · · · ~d is a satellite link of with com- panion . It is clear that the virtual genus

  15. Response of Burrowing Owls to Experimental Removal of Satellite Burrows

    Environmental Sciences and Ecology Websites

    Rosenberg, Daniel K.

    Note Response of Burrowing Owls to Experimental Removal of Satellite Burrows NOELLE A. RONAN,1 of post-emergent nestlings. We experimentally blocked access to burrows within 20 m of nests (satellite burrowing owls to removal of satellite burrows. We compared reproductive performance and nest fidelity

  16. ASTRONOMY 300B: Satellite Presentation Project Fall 2011

    Physics Websites

    Bechtold, Jill

    ASTRONOMY 300B: Satellite Presentation Project Fall 2011 Prof. Bechtold (after a class important points to get across. The Assignment. You are the project manager for an astronomical satellite the committee, your satellite will be decommissioned and allowed to burn up in the atmosphere. Prepare

  17. An abundant population of small irregular satellites around Jupiter

    Physics Websites

    Jewitt, David C.

    irregular satellites around Jupiter Scott S. Sheppard & David C. Jewitt Institute for Astronomy, University ............................................................................................................................................................................. Irregular satellites have eccentric orbits that can be highly inclined or even retrograde relative the regular satellites that follow unin- clined, nearly circular and prograde orbits1 . Rather

  18. Distributed Load-Aware Routing in LEO Satellite Evangelos Papapetrou

    Computer Technologies and Information Sciences Websites

    Papapetrou, Evaggelos

    Distributed Load-Aware Routing in LEO Satellite Networks Evangelos Papapetrou University a distributed approach to handle the complexity of the satellite system and at the same time provides a hop and confirm the positive characteristics of the proposed protocol. I. INTRODUCTION Satellite systems have

  19. Satellite Meeting to the EBBS 2007 Conference 15 September 2007

    Biology and Medicine Websites

    Treves, Alessandro

    Satellite Meeting to the EBBS 2007 Conference 15 September 2007 Stress, Brain and Behaviour Recent, an important goal of this meeting is to promote discussions. The Satellite will start at 10:30 and last till 17: Registration fees for the EBBS conference include participation of the Satellite. In case you want to attend

  20. Magnetic attitude control for satellites Jan Tommy Gravdahl,

    Engineering Websites

    Gravdahl, Jan Tommy

    Magnetic attitude control for satellites Jan Tommy Gravdahl, Department of Engineering Cybernetics it is proven that three-axis stabi- lization of satellites using magnetorqers is uniformly globally. The results are applied to a model of a Norwegian pico-satellite. I. INTRODUCTION Active control

  1. NO2 lidar profile measurements for satellite interpretation and validation

    Geosciences Websites

    Dirksen, Ruud

    NO2 lidar profile measurements for satellite interpretation and validation H. Volten,1 E. J; accepted 24 August 2009; published 19 December 2009. [1] Satellite instruments are efficient detectors of air pollutants such as NO2. However, the interpretation of satellite retrievals is not a trivial

  2. the Satellite applicationS catapult aiming high with Space

    Physics Websites

    the Satellite applicationS catapult aiming high with Space The UK space sector is world class ·enables satellite telecommunications and broadcasting used in everyday life ·contributes to our understanding of climate change through Earth monitoring and observation satellites ·excites young people

  3. How Many GNSS Satellites are GRACE XINGXIN GAO, Member, IEEE

    Engineering Websites

    Gao, Grace Xingxin

    How Many GNSS Satellites are Too Many? GRACE XINGXIN GAO, Member, IEEE University of Illinois at Urbana--Champaign PER ENGE, Fellow, IEEE Stanford University Global Navigation Satellite Systems (GNSS systems. Along with the growth of the systems, the number of satellites will also increase. The whole

  4. Revised 2007-Jan-09 Irregular Satellites of the Planets

    Physics Websites

    Jewitt, David C.

    Revised 2007-Jan-09 Irregular Satellites of the Planets: Capture Processes in the Early Solar in the Solar system possess irregular satellites, charac- terized by large, highly eccentric and/or inclined orbits that are distinct from the nearly circular, uninclined orbits followed by the regular satellites

  5. High Speed Internet Access Through Unidirectional Geostationary Satellite Channels

    Computer Technologies and Information Sciences Websites

    Cohen, Reuven

    High Speed Internet Access Through Unidirectional Geostationary Satellite Channels Ina Minei Reuven user to a direct satellite channel, at a speed 20 times faster than that of an average telephone modem. Communication over satellite links is often characterized by sporadic high bit-error rates and burst losses

  6. HTTPEP: a HTTP Performance Enhancing Proxy for Satellite Systems

    Computer Technologies and Information Sciences Websites

    Sreenan, Cormac J.

    HTTPEP: a HTTP Performance Enhancing Proxy for Satellite Systems Paul Davern, Noor Nashid, Cormac J Communications, Cairo University, Cairo, Egypt. azahran@eecu.cu.edu.eg Broadband satellites enable Internet) that accelerates web-browsing and improves the utilization of satellite resources. We describe HTTP optimizations

  7. Mary E. Kicza Assistant Administrator for Satellite & Information Services

    Environmental Sciences and Ecology Websites

    Mary E. Kicza Assistant Administrator for Satellite & Information Services National Oceanic and Atmospheric Administration (NOAA) Mary E.Kicza is the NOAA Assistant Administrator for Satellite and Information Services. NOAA Satellite and Information Service is dedicated to providing timely access to global

  8. THE CROSSING NUMBER OF SATELLITE KNOTS MARC LACKENBY

    Mathematics Websites

    Lackenby, Marc

    THE CROSSING NUMBER OF SATELLITE KNOTS MARC LACKENBY 1. Introduction One of the most basic are particular cases of satellite knots, which are defined as follows. Let L be a non-trivial knot in the 3-sphere. Then a knot K is a satellite knot with companion knot L if K lies in a regular neighbourhood N

  9. ighly capable small satellites are commonplace today, but this was-

    Physics Websites

    Rhoads, James

    H ighly capable small satellites are commonplace today, but this was- n't always the case. It wasn't until the late 1980s that modern small satellites came on the scene. This new breed of low-profile, low category? A precise description of small satellites, or "lightsats," as they were also called, was lacking

  10. Bandwidth Allocation for IP Traffic Over Satellite Links

    Computer Technologies and Information Sciences Websites

    Kranakis, Evangelos

    Bandwidth Allocation for IP Traffic Over Satellite Links Claude Bélisle, Peter Andreadis, Steve of Computer Science Ottawa, Ontario, Canada K1S 5B6, barbeau@scs.carleton.ca Satellites are being deployed- education as well as e-mail, web browsing, and e-commerce. Satellite bandwidth is, however, an expensive

  11. COLLISIONAL ORIGIN OF FAMILIES OF IRREGULAR SATELLITES David Nesvorny,1

    Physics Websites

    Nesvorny, David

    COLLISIONAL ORIGIN OF FAMILIES OF IRREGULAR SATELLITES David Nesvorny´,1 Cristian Beauge´,2. The origin of this orbital clustering is unknown. Current rates of collisions among satellites of irregular satellites with similar inclinations at Saturn are also yet to be explained. It is conceivable

  12. ORIGINAL ARTICLE Satellite clock bias estimation for iGPS

    Geosciences Websites

    Larson, Kristine

    performance by combining conventional GPS with a communications and ranging broadcast from the Iridium is key to performance. An approach is presented for estimating the bias of each Iridium satellite clock the communications capability of the satellite network from Iridium Satellite LLC, hereafter referred to as Iridium

  13. (Preprint) AAS 13-279 ATMOSPHERIC DENSITY RECONSTRUCTION USING SATELLITE

    Engineering Websites

    Wohlberg, Brendt

    such measurements from a number of satellites, one can estimate the density scale fac- tor (i.e. a correction to an assumed density model). The problem considered here uses measurements from 100 satellites and solves of the history and recent advancements in density modeling using satellite measurements include Refs. 2, 3, and 5

  14. SATELLITE ATM NETWORK ARCHITECTURAL CONSIDERATIONS AND TCP IP PERFORMANCE1

    Computer Technologies and Information Sciences Websites

    Jain, Raj

    that seamlessly interoperate with existing standards, interfaces and higher layer protocols. With the deployment of the satellite communication network, especially the satellite and the earth station have a high cost and must a transport layer protocol like TCP can satisfactorily work over satellite-ATM networks for large delay

  15. Mirror Routing for Satellite Networks With Cross-layer Optimization

    Computer Technologies and Information Sciences Websites

    have been proposed for routing in the Low Earth Orbit (LEO) satellite networks. The multi-layeredMirror Routing for Satellite Networks With Cross-layer Optimization Zhijiang Chang, Georgi routing ap- proaches are envisioned as promising because they use Middle Earth Orbit (MEO) satellite

  16. GROUP SIZE ESTIMATION FOR HYBRID SATELLITE/TERRESTRIAL RELIABLE

    Computer Technologies and Information Sciences Websites

    Mailhes, Corinne

    hop. Satellite communications seem too expensive at first sight. Neverthe- less, in the context updates. Satellite communications are prone to transmission errors (due to atmo- spheric perturbations the satellite communication) grows. Consequently, the pro- posed approach consists of transmitting data via

  17. WDM Polymer Substrate Mode Photonic Interconnects for Satellite Communications

    Engineering Websites

    Chen, Ray

    WDM Polymer Substrate Mode Photonic Interconnects for Satellite Communications Jian Liu Polar is an enabling technology for future satellite communications to increase capacity ofbandwidth and network-3]. Compared with RF satellite communications, they use much smaller antenna aperture size and consume less

  18. Multi-layer Multicast Congestion Control in Satellite Environments

    Computer Technologies and Information Sciences Websites

    Sikdar, Biplab

    an essential role in the future global dig- ital personal communication system. However, satellite net- working1 Multi-layer Multicast Congestion Control in Satellite Environments Jun Peng and Biplab Sikdar errors, and hand-offs in satellite environments seriously interfere with TCP's congestion control

  19. Adaptive Multimedia Communication over Satellite Routed IP Michael Welzl

    Computer Technologies and Information Sciences Websites

    Welzl, Michael

    Adaptive Multimedia Communication over Satellite Routed IP Michael Welzl Telecooperation Department encountered are the same, it seems as though adaptive multimedia communication over satellite has been was chartered in 1997, numerous issues with TCP over satellite have been addressed. Although the difficulties

  20. Analysis of billing data from a hybrid satellite network

    Computer Technologies and Information Sciences Websites

    Trajkovic, Ljiljana

    Analysis of billing data from a hybrid satellite network Savio Lau saviol@cs.sfu.ca Communication University #12;November 29, 2005 Analysis of billing data from a based hybrid satellite Internet service 2 29, 2005 Analysis of billing data from a based hybrid satellite Internet service 3 ChinaSat hybrid

  1. Decision Making Based on Satellite Images: Optimal Fuzzy Clustering Approach

    Computer Technologies and Information Sciences Websites

    Kreinovich, Vladik

    Decision Making Based on Satellite Images: Optimal Fuzzy Clustering Approach Vladik Kreinovich 1, in processing satellite images, we have an enormous amount of information to process. To speed up the in and Formulation of the Problem For satellite imaging, fuzzy clustering is im­ portant. Decision making

  2. Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function

    Astrophysics (arXiv)

    Erik J. Tollerud; James S. Bullock; Louis E. Strigari; Beth Willman

    2008-10-08

    We correct the observed Milky Way satellite luminosity function for luminosity bias using published completeness limits for the Sloan Digital Sky Survey DR5. Assuming that the spatial distribution of Milky Way satellites tracks the subhalos found in the Via Lactea LCDM N-body simulation, we show that there should be between ~300 and ~600 satellites within 400 kpc of the Sun that are brighter than the faintest known dwarf galaxies, and that there may be as many as ~ 1000, depending on assumptions. By taking into account completeness limits, we show that the radial distribution of known Milky Way dwarfs is consistent with our assumption that the full satellite population tracks that of subhalos. These results alleviate the primary worries associated with the so-called missing satellites problem in CDM. We show that future, deep wide-field surveys such as SkyMapper, the Dark Energy Survey (DES), PanSTARRS, and the Large Synoptic Survey Telescope (LSST) will deliver a complete census of ultra-faint dwarf satellites out to the Milky Way virial radius, offer new limits on the free-streaming scale of dark matter, and provide unprecedented constraints on the low-luminosity threshold of galaxy formation.

  3. The dynamics of tidal tails from massive satellites

    Astrophysics (arXiv)

    Jun-Hwan Choi; Martin D. Weinberg; Neal Katz

    2007-08-03

    (Abbreviated) We investigate the dynamical mechanisms responsible for producing tidal tails from dwarf satellites using N-body simulations. We identify two important dynamical co-conspirators: 1) the points where the attractive force of the host halo and satellite are balanced do not occur at equal distances from the satellite centre or at the same equipotential value for massive satellites, breaking the morphological symmetry of the leading and trailing tails; and 2) the escaped ejecta in the leading (trailing) tail continues to be decelerated (accelerated) by the satellite's gravity leading to large offsets of the ejecta orbits from the satellite orbit. The effect of the satellite's self gravity decreases only weakly with a decreasing ratio of satellite mass to host halo mass, demonstrating the importance of these effects over a wide range of subhalo masses. Not only will the morphology of the leading and trailing tails for massive satellites be different, but the observed radial velocities of the tails will be displaced from that of the satellite orbit; both the displacement and the peak radial velocity is proportional to satellite mass. If the tails are assumed to follow the progenitor satellite orbits, the tails from satellites with masses greater than 0.0001 of the host halo virial mass in a spherical halo will appear to indicate a flattened halo. Therefore, a constraint on the Milky Way halo shape using tidal streams requires mass-dependent modelling. Similarly, we compute the the distribution of tail orbits both in E_{r}-r^{-2} space and in E-L_{z} space, advocated for identifying satellite stream relics. The acceleration of ejecta by a massive satellite during escape spreads the velocity distribution and obscures the signature of a well-defined ``moving group'' in phase space.

  4. Search for Unknown Dark Matter Satellites of the Milky Way

    HEP - Phenomenology (arXiv)

    Alex Drlica-Wagner; Ping Wang; Elliott Bloom; Louis Strigari; for the Fermi-LAT Collaboration

    2011-11-14

    We present a search for Galactic dark matter (DM) satellites using the Large Area Telescope (LAT). N-body simulations based on the Lambda-CDM model of cosmology predict a large number of as yet unobserved Galactic DM satellites. These satellites could potentially produce gamma rays through the self-annihilation of DM particles. Some DM satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We searched for LAT sources with these characteristics. We found no candidate DM satellites matching these criteria in one year of LAT data and interpreted this result in the context of N-body simulations.

  5. The Principle of Navigation Constellation Composed of SIGSO Communication Satellites

    CERN Preprints

    Ji, Hai-Fu; Ai, Guo-Xiang; Shi, Hu-Li

    2012-01-01

    The Chinese Area Positioning System (CAPS), a navigation system based on GEO communication satellites, was developed in 2002 by astronomers at Chinese Academy of Sciences. Extensive positioning experiments of CAPS have been performed since 2005. On the basis of CAPS, this paper studies the principle of navigation constellation composed of Slightly Inclined Geostationary Orbit (SIGSO) communication satellites. SIGSO satellites are derived from end-of-life Geostationary Orbit (GEO) satellites under inclined orbit operation. Considering the abundant frequency resources of SIGSO satellites, multi-frequency observations could be conducted to enhance the precision of pseudorange measurements and ameliorate the positioning performence. The constellation composed of two GEO satellites and four SIGSO satellites with inclination of 5 degrees can provide the most territory of China with 24-hour maximum PDOP less than 42. With synthetic utilization of the truncated precise (TP) code and physical augmentation factor in fo...

  6. Satellites in Discs: Regulating the Accretion Luminosity

    Astrophysics (arXiv)

    Dave Syer; Cathie Clarke

    1995-05-04

    We demonstrate, using a simple analytic model, that the presence of a massive satellite can globally modify the structure and emission properties of an accretion disc to which it is tidally coupled. We show, using two levels of numerical approximation, that the analytic model gives reasonable results. The results are applicable to two astrophysical situations. In the case of an active galactic nucleus, we consider the case of a $\\sim 10^3\\Msun$ compact companion to the central black-hole and show that it could modulate the emitted spectrum on a timescale of $\\sim10^5$ years. In the case of a T Tauri accretion disc, a satellite such as a sub-dwarf or giant planet could modify the disc spectral energy distribution over a substantial fraction of the T Tauri star lifetime.

  7. Efficient statistical classification of satellite measurements

    CERN Preprints

    Mills, Peter

    2012-01-01

    Supervised statistical classification is a vital tool for satellite image processing. It is useful not only when a discrete result, such as feature extraction or surface type, is required, but also for continuum retrievals by dividing the quantity of interest into discrete ranges. Because of the high resolution of modern satellite instruments and because of the requirement for real-time processing, any algorithm has to be fast to be useful. Here we describe an algorithm based on kernel estimation called Adaptive Gaussian Filtering that incorporates several innovations to produce superior efficiency as compared to three other popular methods: k-nearest-neighbour (KNN), Learning Vector Quantization (LVQ) and Support Vector Machines (SVM). This efficiency is gained with no compromises: accuracy is maintained, while estimates of the conditional probabilities are returned. These are useful not only to gauge the accuracy of an estimate in the absence of its true value, but also to re-calibrate a retrieved image and...

  8. On Small Satellites for Oceanography: A Survey

    CERN Preprints

    Guerra, André G C; Villate, Jaime; Agelet, Fernando Aguado; Bertolami, Orfeu; Rajan, Kanna

    2015-01-01

    The recent explosive growth of small satellite operations driven primarily from an academic or pedagogical need, has demonstrated the viability of commercial-off-the-shelf technologies in space. They have also leveraged and shown the need for development of compatible sensors primarily aimed for Earth observation tasks including monitoring terrestrial domains, communications and engineering tests. However, one domain that these platforms have not yet made substantial inroads into, is in the ocean sciences. Remote sensing has long been within the repertoire of tools for oceanographers to study dynamic large scale physical phenomena, such as gyres and fronts, bio-geochemical process transport, primary productivity and process studies in the coastal ocean. We argue that the time has come for micro and nano satellites (with mass smaller than 100 kg and 2 to 3 year development times) designed, built, tested and flown by academic departments, for coordinated observations with robotic assets in situ. We do so primar...

  9. Satellite measurement of the Hannay angle

    General Relativity & Quantum Cosmology (arXiv)

    Alessandro D. A. M. Spallicci

    2004-09-20

    The concept of a measurement of the yet unevaluated Hannay angle, by means of an Earth-bound satellite, adiabatically driven by the Moon, is shown herein. Numerical estimates are given for the angles, the orbital displacements, the shortening of the orbital periods, for different altitudes. It is concluded that the Hannay effect is measurable in high Earth orbits, by means of atomic clocks, accurate Time & Frequency transfer system and precise positioning.

  10. Galaxy Satellites and the Weak Equivalence Principle

    HEP - Phenomenology (arXiv)

    J. A. Keselman; A. Nusser; P. J. E. Peebles

    2009-08-29

    Numerical simulations of the effect of a long-range scalar interaction (LRSI) acting only on nonbaryonic dark matter, with strength comparable to gravity, show patterns of disruption of satellites that can agree with what is seen in the Milky Way. This includes the symmetric Sagittarius stellar stream. The exception presented here to the Kesden and Kamionkowski demonstration that an LRSI tends to produce distinctly asymmetric streams follows if the LRSI is strong enough to separate the stars from the dark matter before tidal disruption of the stellar component, and if stars dominate the mass in the luminous part of the satellite. It requires that the Sgr galaxy now contains little dark matter, which may be consistent with the Sgr stellar velocity dispersion, for in the simulation the dispersion at pericenter exceeds virial. We present other examples of simulations in which a strong LRSI produces satellites with large mass-to-light ratio, as in Draco, or free streams of stars, which might be compared to "orphan" streams.

  11. Photometric Survey of the Irregular Satellites

    Astrophysics (arXiv)

    Tommy Grav; Matthew J. Holman; Brett Gladman; Kaare Aksnes

    2003-01-02

    We present BVRI colors of 13 Jovian and 8 Saturnian irregular satellites obtained with the 2.56m Nordic Optical Telescope on La Palma, the 6.5m Magellan Baade Telescope on La Campanas, and the 6m MMT on Mt. Hopkins. The observations were performed between December 2001 to March 2002. Nearly all of the known irregular satellites can be divided into two distinct classes based on their colors. One, the grey color class, has the similar colors to the C-type asteroid, and the other, the light red color class, has colors similar to P/D-type asteroids. We also find at least one object, the Jovian irregular J XXIII Kalyke, that has colors similar to the red colored Centaurs/TNOs, although its classification is unsecure. We also find that there is a correlation between the physical properties and dynamical properties of the irregular satellites. Most of the dynamical clusters have homogeneous colors, which points to single homogeneous progenitors being cratered or fragmented as the source of each individual cluster. The heterogeneous colored clusters are most easily explained by assuming that there are several dynamical clusters in the area, rather than just one.

  12. A Formation Scenario for the Disk of Satellites: Accretion of Satellites during Mergers

    CERN Preprints

    Smith, Rory; Bournaud, Frederic; Yi, Sukyoung K

    2015-01-01

    The Disk of Satellites (DoS) observed in the Andromeda galaxy is a thin and extended group of satellites, nearly perpendicular to the disk plane, that share a common direction of rotation about the centre of Andromeda. Although a DoS is also observed in the Milky Way galaxy, the prevalance of such structures in more distant galaxies remains controversial. Explanations for the formation of such DoSs vary widely from filamentary infall, or flattening due to the potential field from large scale structure, to galaxy interactions in a Mondian paradigm. Here we present an alternative scenario -- during a merger, a galaxy may bring its own satellite population when merging with another galaxy. We demonstrate how, under the correct circumstances, during the coalescence of the two galaxies, the satellite population can be spread into an extended, flattened structure, with a common direction of rotation about the merger remnant. We investigate the key parameters of the interaction, and the satellite population, that ar...

  13. LARES succesfully launched in orbit: satellite and mission description

    CERN Preprints

    Paolozzi, Antonio

    2013-01-01

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation...

  14. Color Dependence in the Spatial Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Jacqueline Chen

    2008-04-08

    We explore the color dependence of the radial profile of satellite galaxies around isolated parent galaxies. Samples of potential satellites selected from large galaxy redshift surveys are significantly contaminated by interlopers -- objects not bound to the parent galaxy. We use the Sloan Digital Sky Survey to estimate the interloper fraction in samples of candidate satellite galaxies. We show that samples of red and blue satellites have different interloper populations: a larger fraction of blue galaxies are likely to be interlopers compared to red galaxies. Both with and without interloper subtraction, the radial profile of blue satellites is significantly shallower than that of red satellites. In addition, while red and blue primaries have different interloper fractions, the slope of the corrected radial profiles are consistent after interloper correction. We discuss the implications of these results for galaxy formation models.

  15. Some Implications of the Anisotropic Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Dennis Zaritsky; Anthony H. Gonzalez

    1999-08-17

    We examine a possible connection between the anisotropic distribution of satellite galaxies around giant spiral galaxies and the evolution of satellite systems. The observed polar anisotropy (Zaritsky et al.1997) is either imprinted by initial conditions or develops from an initially symmetric distribution. We attempt to discriminate between these two possibilities by exploring the implications of the latter one. From the observed distribution of satellite galaxies relative to the primary galaxy's disk, we derive constrains on the orbital inclinations of the current satellite population. Using this derived inclination limit and assuming that the initial population had no preferred orbital inclination, we estimate the size of the hypothesized original population. We find that our best-fit models imply a population of destroyed (or inhibited) satellites whose combined luminosity (assuming the same M/L as for the observed satellites) is between 18% and 103% of the current disk luminosity.

  16. From Tidal Dwarf Galaxies to Satellite Galaxies

    Astrophysics (arXiv)

    F. Bournaud; P. -A. Duc

    2006-05-15

    Cosmological models have granted dwarf galaxies a key role: their properties constrain the distribution of dark matter and the physical evolution of their hosts. There is increasing evidence that objects with masses of dwarf galaxies form in the tidal tails of colliding galaxies and speculations that they could become satellite-like galaxies around their progenitors and thus be cosmologically important. Yet, whether these "Tidal Dwarf Galaxies" (TDGs) candidates are really long-lived and not only present in young interacting systems is still an open question to which numerical simulations may give answers. We present a set of 96 simulations of colliding galaxies with various mass ratios and encounter geometries, and statistically study the evolution of their TDG candidates. Among the 593 substructures initially identified in tidal tails, about 75% fall back onto their progenitor or are disrupted in a few 10^8 years. The remaining 25% become long-lived bound objects that typically survive more than 2Gyr with masses above 10^8 M_sun. These long-lived, satellite-like objects, are found to form in the outer most regions of the tidal tails. We infer several basic properties that dwarf galaxies should meet to have a tidal origin and apply these criteria to the Local Group dwarfs. We also find that the presence of TDGs would foster the anisotropy observed in the distribution of satellite galaxies around their host. Identifying the conditions required for interacting systems to form long-lived tidal dwarfs, we roughly estimate their contribution to the overall population of dwarfs. We conclude that a small but significant fraction of them - typically a few percent, and possibly more in dense environments or around early-type galaxies - could be of tidal origin.

  17. Andromeda and its satellites - a kinematic perspective

    CERN Preprints

    Collins, Michelle L M; Chapman, Scott C

    2012-01-01

    Using spectroscopic data taken with Keck II DEIMOS by the Z-PAndAS team in the Andromeda-Triangulum region, I present a comparison of the disc and satellite systems of Andromeda with those of our own Galaxy. I discuss the observed discrepancies between the masses and scale radii of Andromeda dwarf spheroidal galaxies of a given luminosity with those of the Milky Way. I also also present an analysis of the newly discovered M31 thick disc, which is measured to be hotter, more extended and thicker than that seen in the Milky Way.

  18. Modelling and control of satellite formations 

    Texas A&M University - TxSpace

    Vaddi, Veera Venkata Sesha Sai

    2004-09-30

    of reference frames. Shown in Fig.(1.1) are the inertial and LVLH reference frames. The motion along x;y; and z will also be referred to as radial, along-track, and out- of-plane motion, respectively. 3 Fig. 1.1: Reference frames The choices for the coordinates... to design impulsive control laws using orbital element models. 1.1 Inertial Coordinates The equations of motion of a satellite in inertial coordinates, under the in°uence of gravitational e®ects is given below: 4 Ä = ¡Ár (1.1) where, r = [X Y Z...

  19. Spatial and kinematic alignments between central and satellite halos

    Astrophysics (arXiv)

    A. Faltenbacher; Y. P. Jing; Cheng Li; Shude Mao; H. J. Mo; Anna Pasquali; Frank C. van den Bosch

    2007-12-18

    Based on a cosmological N-body simulation we analyze spatial and kinematic alignments of satellite halos within six times the virial radius of group size host halos (Rvir). We measure three different types of spatial alignment: halo alignment between the orientation of the group central substructure (GCS) and the distribution of its satellites, radial alignment between the orientation of a satellite and the direction towards its GCS, and direct alignment between the orientation of the GCS and that of its satellites. In analogy we use the directions of satellite velocities and probe three further types of alignment: the radial velocity alignment between the satellite velocity and connecting line between satellite and GCS, the halo velocity alignment between the orientation of the GCS and satellite velocities and the auto velocity alignment between the satellites orientations and their velocities. We find that satellites are preferentially located along the major axis of the GCS within at least 6 Rvir (the range probed here). Furthermore, satellites preferentially point towards the GCS. The most pronounced signal is detected on small scales but a detectable signal extends out to 6 Rvir. The direct alignment signal is weaker, however a systematic trend is visible at distances < 2 Rvir. All velocity alignments are highly significant on small scales. Our results suggest that the halo alignment reflects the filamentary large scale structure which extends far beyond the virial radii of the groups. In contrast, the main contribution to the radial alignment arises from the adjustment of the satellite orientations in the group tidal field. The projected data reveal good agreement with recent results derived from large galaxy surveys. (abridged)

  20. A Survey for Outer Satellites of Mars: Limits to Completeness

    Astrophysics (arXiv)

    Scott S. Sheppard; David Jewitt; Jan Kleyna

    2004-09-22

    We surveyed the Hill sphere of Mars for irregular satellites. Our search covered nearly the entire Hill Sphere, but scattered light from Mars excluded the inner few arcminutes where the satellites Phobos and Deimos reside. No new satellites were found to an apparent limiting red magnitude of 23.5, which corresponds to radii of about 0.09 km using an albedo of 0.07.

  1. The dynamics of satellite disruption in cold dark matter haloes

    Astrophysics (arXiv)

    Jun-Hwan Choi; Martin D. Weinberg; Neal Katz

    2009-08-17

    We investigate the physical mechanisms of tidal heating and satellite disruption in cold dark matter host haloes using N-body simulations based on cosmological initial conditions. We show the importance of resonant shocks and resonant torques with the host halo to satellite heating. A resonant shock (torque) couples the radial (tangential) motion of a satellite in its orbit to its phase space. For a satellite on a circular orbit, an ILR-like resonance dominates the heating and this heating results in continuous satellite mass loss. We estimate the requirements for simulations to achieve these dynamics using perturbation theory. Both resonant shocks and resonant torques affect satellites on eccentric orbits. We demonstrate that satellite mass loss is an outside-in process in energy space; a satellite's stars and gas are thus protected by their own halo against tidal stripping. We simulate the evolution of a halo similar to the Large Magellanic Cloud (LMC) in our Galactic dark matter halo and conclude that the LMC stars have not yet been stripped. Finally, we present a simple algorithm for estimating the evolution of satellite mass that includes both shock heating and resonant torques.

  2. Notes to Saturn satellites Ijiraq and Kiviuq mutual close encounters

    Astrophysics (arXiv)

    A. E. Rosaev

    2006-02-01

    The problem of origin of outer irregular satellites of large planets is considered. The capture way of their origin most probable, however there is not detail theory. There are a number of irregular satellites, discovered in recent time. It gives an ability to investigate the statistics of orbital interaction and try to reconstruct real collision history of these objects We restrict this consideration by pair of orbits with close elements: Kiviuq and Ijiraq and determine period of close encounters between this satellites. It may be considered as a first step on road to the construction of theory of origin of the abundant class of irregular satellites.

  3. Designing Satellite Communication Networks by Zero-One Quadratic Programming

    MIT - DSpace

    Helme, Marcia P.

    In satellite communications networks, distinctive facilities called homing stations perform special transmission functions. Local demand nodes clustered around each homing station communicate with each other via a local ...

  4. The Spatial Distribution of Satellite Galaxies Selected from Redshift Space

    CERN Preprints

    Agustsson, Ingolfur

    2015-01-01

    We investigate the spatial distribution of satellite galaxies that were obtained from a mock redshift survey of the first Millennium Run simulation. The satellites were identified using typical redshift space criteria and, hence, the sample includes both genuine satellites and a large number of interlopers. As expected from previous work, the 3D locations of the satellites are well-fitted by a combination of a Navarro, Frenk & White (NFW) density profile and a power law. At fixed stellar mass, the NFW scale parameter, r_s, for the satellite distribution of red hosts exceeds that for the satellite distribution of blue hosts. In both cases the dependence of r_s on host stellar mass is well-fitted by a power law. For the satellites of red hosts, r_s^{red} \\propto (M_\\ast / M_sun)^{0.71 \\pm 0.05} while for the satellites of blue hosts, r_s^{blue} \\propto (M_\\ast / M_sun)^{0.48 \\pm 0.07}. For hosts with stellar masses greater than 4.0E+10 M_sun, the satellite distribution around blue hosts is much more concent...

  5. The subhalo - satellite connection and the fate of disrupted satellite galaxies

    Astrophysics (arXiv)

    Xiaohu Yang; H. J. Mo; Frank C. van den Bosch

    2008-11-14

    In the standard paradigm, satellite galaxies are believed to be associated with the population of dark matter subhalos. In this paper, we use the conditional stellar mass functions of {\\it satellite galaxies} obtained from a large galaxy group catalogue together with models of the subhalo mass functions to explore the fraction and fate of stripped stars from satellites in galaxy groups and clusters of different masses. The majority of the stripped stars in massive halos are predicted to end up as intra-cluster stars, and the predicted amounts of the intra-cluster component as a function of the velocity dispersion of galaxy system match well the observational results obtained by Gonzalez et al. (2007). The fraction of the mass in the stripped stars to that remain bound in the central and satellite galaxies is the highest ($\\sim 40%$ of the total stellar mass) in halos with masses $M_h\\sim 10^{14}\\msunh$. If all these stars end up in the intra-cluster component (Max), or maximum of them are accreted into the central galaxy (Min), then we can predict that a maximum $\\sim 19%$ and a minimum $\\sim 5%$ of the total stars in the whole universe are in terms of the diffused intra-cluster component. In the former case, in massive halos with $M_h \\sim 10^{15} \\msunh$, the stellar mass of the intra-cluster component is roughly 6 times as large as that of the central galaxy. This factor decreases to $\\sim 2$, 1 and 0.1 in halos with $M_h \\sim 10^{14}$, $10^{13}$, and $10^{12} \\msunh$, respectively. The total amount of stars stripped from satellite galaxies is insufficient to build up the central galaxies in halos with masses $\\la 10^{12.5}\\msunh$, and so the quenching of star formation must occur in halos with higher masses. Abridged.

  6. Fast object detection for use onboard satellites

    Astrophysics (arXiv)

    Martin Bange; Stefan Jordan; Michael Biermann; Thomas Kaempke; R alf-Dieter Scholz

    2003-01-30

    We propose an object detection algorithm which is efficient and fast enough to be used in (almost) real time with the limited computer capacities onboard satellites. For stars below the saturation limit of the CCD detectors it is based on a four neighbourhood local maximum criterion in order to find the centre of a stellar image. For saturated stars it is based on the assumption that the image is increasing monotonically towards the centre in the unsaturated part of the image. The algorithm also calculates approximate stellar magnitudes and efficiently rejects most of the cosmics which would otherwise lead to a large number of false detections. The quality of the algorithm was evaluated with the help of a large set of simulated data for the DIVA satellite mission; different assumptions were made for the noise level, and the presence of cosmics or for a variable sky background. We could show that our algorithm fulfills the requirements for DIVA; only in the case of simulated images which included the bright galaxy M31 some fainter stars could not be detected in the galaxy's vicinity. Since stellar images contain large areas without any stars, we propose an additional block-skipping algorithm which can be coded on special-purpose hardware.

  7. The Big Occulting Steerable Satellite (BOSS)

    Astrophysics (arXiv)

    Craig J. Copi; Glenn D. Starkman

    1999-04-29

    Natural (such as lunar) occultations have long been used to study sources on small angular scales, while coronographs have been used to study high contrast sources. We propose launching the Big Occulting Steerable Satellite (BOSS), a large steerable occulting satellite to combine both of these techniques. BOSS will have several advantages over standard occulting bodies. BOSS would block all but about 4e-5 of the light at 1 micron in the region of interest around the star for planet detections. Because the occultation occurs outside the telescope, scattering inside the telescope does not degrade this performance. BOSS could be combined with a space telescope at the Earth-Sun L2 point to yield very long integration times, in excess of 3000 seconds. If placed in Earth orbit, integration times of 160--1600 seconds can be achieved from most major telescope sites for objects in over 90% of the sky. Applications for BOSS include direct imaging of planets around nearby stars. Planets separated by as little as 0.1--0.25 arcseconds from the star they orbit could be seen down to a relative intensity as little as 1e-9 around a magnitude 8 (or brighter) star. Other applications include ultra-high resolution imaging of compound sources, such as microlensed stars and quasars, down to a resolution as little as 0.1 milliarcseconds.

  8. ISCTM/MJFF Satellite Meeting 22 February/S Murphy 1

    Mathematics Websites

    Murphy, Susan A.

    ISCTM/MJFF Satellite Meeting 22 February/S Murphy 1 #12;ISCTM/MJFF Satellite Meeting 22 February/MJFF Satellite Meeting 22 February/S Murphy 3 #12;ISCTM/MJFF Satellite Meeting 22 February/S Murphy 4 #12;ISCTM/MJFF Satellite Meeting 22 February/S Murphy 5 First review the general principles behind pilot studies. The key

  9. Lake level variations from satellite radar altimetry with

    Geosciences Websites

    Stuttgart, Universität

    Lake level variations from satellite radar altimetry with retracking of multi-leading edge Shirzad with retracking of multi-leading edge 1 #12;RADAR principle http://www.altimetry.info Lake level variations from satellite radar altimetry with retracking of multi-leading edge 2 #12;How can we have more precise water

  10. Effects of Rain Attenuation on Satellite Video Transmission

    Computer Technologies and Information Sciences Websites

    Winkler, Stefan

    Effects of Rain Attenuation on Satellite Video Transmission Yee Hui Lee and Stefan Winkler Nanyang, email: stefan.winkler@adsc.com.sg Abstract--Heavy convective rain events are often experienced] caused by rain or cloud cover. Poor link conditions can lead to signal outage. Satellite service

  11. Physical aspects to consider in radiometric calibration of satellite images

    CERN Preprints

    Delgado-Correal, Camilo

    2012-01-01

    It does a revision about the physical principles involved in digital processing of satellite images, more specifically in radiometric calibration of them. It shows a conceptual description of the interaction between radiation and atmosphere and radiation and soil in order to help the reader understand in more detail which means the information contained in satellite images.

  12. NOAA's National Environmental Satellite, Data, and Information Service

    Geosciences Websites

    to support operational space weather monitoring and forecasting. NOAA Satellites Serve the Nation · NOAA observing systems that provide these data are the foundation of the environmental intelligence NOAA provides developed to succeed POES and GOES, the Joint Polar Satellite System (JPSS) and GOES-R programs

  13. State Estimation 6.4 Satellite Navigation Systems

    Computer Technologies and Information Sciences Websites

    Nourbakhsh, Illah

    Chapter 6 State Estimation Part 4 6.4 Satellite Navigation Systems Mobile Robotics - Prof Alonzo. ­ Like electric power and telephony. ­ Works continuously everywhere 24 hours a day. · Revolutionized Kelly, CMU RI1 #12;Outline · 6.4 Satellite Navigation Systems ­ 6.4.1 Introduction ­ 6

  14. NASA ACTS SATELLITE: A DISASTER RECOVERY TEST Dr. Hans Kruse

    Engineering Websites

    Kruse, Hans

    NASA ACTS SATELLITE: A DISASTER RECOVERY TEST Dr. Hans Kruse School of Communications Systems In September 1993, NASA launched its long- awaited Advanced Communication Technology (ACTS) satellite. ACTS links. The ACTS Disaster Recovery Project was designed to test the Bank's ability to by

  15. Digital Video Broadcasting By Satellite Matthew C. Valenti

    Computer Technologies and Information Sciences Websites

    Valenti, Matthew C.

    Providers Digital Satellite Television in the United States DirecTV Spinoff of Hughes Network Systems. Began Network Systems. DirecTV. M.C. Valenti ( Lane Department of Computer Science and Electrical Engineering West Virginia UniverLDPC Codes Apr. 2, 2012 2 / 41 #12;Outline 1 Satellite Television Standards 2 DVB

  16. Luminous Satellites II: Spatial Distribution, Luminosity Function and Cosmic Evolution

    CERN Preprints

    Nierenberg, A M; Treu, T; Marshall, P J; Fassnacht, C D; Busha, Michael T

    2012-01-01

    We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies ($\\log_{10}[M_{h}^*/M\\odot]>10.5$) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology and satellite luminosity. Exploiting the depth and resolution of the COSMOS HST images, we detect satellites up to eight magnitudes fainter than the host galaxies and as close as 0.3 (1.4) arcseconds (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that $P(R)\\propto R^{\\rpower}$, we find $\\rpower=-1.1\\pm 0.3$. We find no dependency of $\\rpower$ on host stellar mass, redshift, morphology or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is depe...

  17. Network Mobility in Satellite Networks: Architecture and the Protocol

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    for multiple IP-enabled devices onboard a satellite that hands off between ground stations. Network Mo- bility reported in this paper was funded by NASA Grant NNX06AE44G. resulting in the mobility of onboard devices protocols are inefficient for handling the mobility of multiple IP-enabled devices onboard satellites due

  18. Embedding planning technology into satellite systems David Kortenkamp

    Engineering Websites

    Kortenkamp, David

    . This paper describes an on-board planning and execution system for satellites that schedules system tasks. Introduction There is an increasing need to develop on-board autonomy for satellite systems, both to increase, threat response, and task execution is a key challenge for these systems. HAMMER integrates an on-board

  19. Asteroid 2014 OL339: yet another Earth quasi-satellite

    CERN Preprints

    Marcos, C de la Fuente

    2014-01-01

    Our planet has one permanently bound satellite -the Moon-, a likely large number of mini-moons or transient irregular natural satellites, and three temporary natural retrograde satellites or quasi-satellites. These quasi-moons -(164207) 2004 GU9, (277810) 2006 FV35 and 2013 LX28- are unbound companions to the Earth. The orbital evolution of quasi-satellites may transform them into temporarily bound satellites of our planet. Here, we study the dynamical evolution of the recently discovered Aten asteroid 2014 OL339 to show that it is currently following a quasi-satellite orbit with respect to the Earth. This episode started at least about 775 yr ago and it will end 165 yr from now. The orbit of this object is quite chaotic and together with 164207 are the most unstable of the known Earth quasi-satellites. This group of minor bodies is, dynamically speaking, very heterogeneous but three of them exhibit Kozai-like dynamics: the argument of perihelion of 164207 oscillates around -90 degrees, the one of 277810 libr...

  20. Ocean Remote Sensing from Satellites Ted Strub, Burt 406

    Geosciences Websites

    Wright, Dawn Jeannine

    ://cioss.coas.oregonstate.edu/CIOSS/ · General Background · Examples, Measuring ­ Surface Temperature ­ Ocean Color/Optics ­ Sea Surface Height spill: Satellite "images" may "track" surface features: IR surface temperatures, visible features is expensive · Satellites can acquire measurements quickly over large areas BUT... · Space: a harsh environment

  1. ANALYZING TIME SERIES OF SATELLITE IMAGERY USING TEMPORAL MAP ALGEBRA

    Environmental Sciences and Ecology Websites

    Mennis, Jeremy

    ANALYZING TIME SERIES OF SATELLITE IMAGERY USING TEMPORAL MAP ALGEBRA Jeremy Mennis Department rviger@usgs.gov ABSTRACT This paper presents the application of a set of spatio-temporal satellite image analysis functions based on temporal map algebra. The temporal map algebra functions treat time series

  2. On the scarcity of Magellanic Cloud-like satellites

    CERN Preprints

    James, Phil A

    2010-01-01

    We have used H alpha narrow-band imaging to search for star-forming satellite galaxies around 143 luminous spiral galaxies, with the goal of quantifying the frequency of occurrence of satellites resembling the Magellanic Clouds, around galaxies comparable to the Milky Way. For two-thirds of the central galaxies, no star-forming satellites are found, down to luminosities and star-formation rates well below those of the Magellanic Clouds. A total of 62 satellites is found, associated with 47 of the central galaxies searched. The R-band magnitude difference between central galaxies and their satellites has a median value of 4.6 mag, and a maximum of 10.2 mag. The mean projected separation of the satellites from their central galaxies is 81 kpc, or 98 kpc for systems beyond 30 Mpc. Thus star-forming satellites are quite rare, and the Milky Way is unusual both for the luminosity and the proximity of its two brightest satellites. We also find that the Clouds themselves are unusual in that they appear to form a boun...

  3. Peer-to-Peer Refueling for Circular Satellite Constellations

    Engineering Websites

    Tsiotras, Panagiotis

    Peer-to-Peer Refueling for Circular Satellite Constellations Haijun Shen and Panagiotis Tsiotras constellation. It is assumed that there is no fuel delivered to the constellation from an external source. Instead, all satellites in the constellation are assumed to be capable of refueling each other (peer

  4. IP ROUTING ISSUES IN SATELLITE CONSTELLATION NETWORKS A. CLERGET,2

    Engineering Websites

    Wood, Lloyd

    1 IP ROUTING ISSUES IN SATELLITE CONSTELLATION NETWORKS L. WOOD,*1 A. CLERGET,2 I. ANDRIKOPOULOS,1 broadband satellite constellation networks, currently under development, will be required to transport IP traffic. A case can be made for implementing IP routing directly within the constellation network

  5. Internetworking with satellite constellations PhD viva presentation

    Engineering Websites

    Wood, Lloyd

    Internetworking with satellite constellations PhD viva presentation Centre for Communication;Internetworking with satellite constellations - Lloyd Wood 2 Overview of this talk and Lloyd's PhD work constellation. · TCP across LEO/MEO mesh networks ­ performance influences the approach to routing design

  6. Performance Study of Routing Algorithms for LEO Satellite Constellations

    Computer Technologies and Information Sciences Websites

    Papapetrou, Evaggelos

    1 Performance Study of Routing Algorithms for LEO Satellite Constellations Ioannis Gragopoulos A comparative study of routing techniques is carried out on complicated LEO constellations interconnecting high the situation of current satellite constellations which are far from being congested [1]. There are a number

  7. A Region Void of Irregular Satellites Around Jupiter

    Astrophysics (arXiv)

    N. Haghighipour; D. Jewitt

    2008-05-24

    An interesting feature of the giant planets of our solar system is the existence of regions around these objects where no irregular satellites are observed. Surveys have shown that, around Jupiter, such a region extends from the outermost regular satellite Callisto, to the vicinity of Themisto, the innermost irregular satellite. To understand the reason for the existence of such a satellite-void region, we have studied the dynamical evolution of Jovian irregulars by numerically integrating the orbits of several hundred test particles, distributed in a region between 30 and 80 Jupiter-radii, for different values of their semimajor axes, orbital eccentricities, and inclinations. As expected, our simulations indicate that objects in or close to the influence zones of the Galilean satellites become unstable because of interactions with Ganymede and Callisto. However, these perturbations cannot account for the lack of irregular satellites in the entire region between Callisto and Themisto. It is suggested that at distances between 60 and 80 Jupiter-radii, Ganymede and Callisto may have long-term perturbative effects, which may require the integrations to be extended to times much longer than 10 Myr. The interactions of irregular satellites with protosatellites of Jupiter at the time of the formation of Jovian regulars may also be a destabilizing mechanism in this region. We present the results of our numerical simulations and discuss their applicability to similar satellite void-regions around other giant planets.

  8. Resonant Thickening of Disks by Small Satellite Galaxies

    Astrophysics (arXiv)

    J. A. Sellwood; Robert W. Nelson; Scott Tremaine

    1998-05-12

    We study the vertical heating and thickening of galaxy disks due to accretion of small satellites. Our simulations are restricted to axial symmetry, which largely eliminates numerical evolution of the target galaxy but requires the trajectory of the satellite to be along the symmetry axis of the target. We find that direct heating of disk stars by the satellite is not important because the satellite's gravitational perturbation has little power at frequencies resonant with the vertical stellar orbits. The satellite does little damage to the disk until its decaying orbit resonantly excites large-scale disk bending waves. Bending waves can damp through dynamical friction from the halo or internal wave-particle resonances; we find that wave-particle resonances dominate the damping. The principal vertical heating mechanism is therefore dissipation of bending waves at resonances with stellar orbits in the disk. Energy can thus be deposited some distance from the point of impact of the satellite. The net heating from a tightly bound satellite can be substantial, but satellites that are tidally disrupted before they are able to excite bending waves do not thicken the disk.

  9. Motion properties of satellites around external spiral galaxies

    Astrophysics (arXiv)

    M. Azzaro; F. Prada; C. M. Gutiérrez

    2003-10-17

    We are analyzing a sample of closeby galaxy systems, each comprising a bright isolated spiral and its satellites. We find an excess (56%) of prograde satellites over retrograde, which basically holds for all angular displacements from the primary major axis. Monte Carlo simulations show that interlopers and mixing systems at different distances in the sample should not affect porcentages sensibly.

  10. Calculating Change Curves for Multitemporal Satellite Imagery: Mount St. Helens

    Environmental Sciences and Ecology Websites

    Lawrence, Rick L.

    pixels. We demon- etation change (e.g., Muchoney and Haack, 1994), much strated the use of change curveCalculating Change Curves for Multitemporal Satellite Imagery: Mount St. Helens 1980­1995 Rick L satellite imagery using change curves. The The recovery of vegetation following the 1980 eruption method

  11. 17.5 CHARACTERISTICS OF SUPERCELLULAR SATELLITE TORNADOES Roger Edwards

    Geosciences Websites

    17.5 CHARACTERISTICS OF SUPERCELLULAR SATELLITE TORNADOES Roger Edwards 1 Storm Prediction Center tornado) known as a satellite tornado (hereafter, ST). For the purpose of this examination, STs, main tornado (hereafter, MT) and entirely within the MT lifespan; Orbiting the MT in a direction

  12. Micro-Navigation Satellite Network Design and Analysis

    Engineering Websites

    Won, Chang-Hee

    Micro-Navigation Satellite Network Design and Analysis Bei Kang, Electrical and Computer University. His research interests include navigation, stochastic optimal control, systems engineering for successful navigation. In this paper, we design and analyze the micro-navigation satellite network that share

  13. "Globalstar, Iridium and other Satellite-Based Mobile Phone

    Computer Technologies and Information Sciences Websites

    1 "Globalstar, Iridium and other Satellite-Based Mobile Phone Systems: How Do they Work and Where formed in the early 90's ­ Iridium [LEO, intersatellite links] ­ Globalstar [LEO, satellite diversity in their Flying Machines Iridium LEO Polar TDMA Globalstar LEO Inclined CDMA ICO MEO Inclined Custom Constellation

  14. Cyclone Global Navigation Satellite System (CYGNSS) Mission Overview

    Engineering Websites

    Eustice, Ryan

    _Handout_B The CYGNSS mission is comprised of 8 Low Earth Orbiting (LEO) spacecraft (S/C) that receive both direct-resolutionwindfieldimageryofTCgenesis,intensificationanddecay. GPS satellites CYGNSS Observatories Primary Objectives: · Measure ocean surface wind speed in all Global Navigation Satellite System (CYGNSS) Mission Timeline Delay Doppler Mapping Instrument (DDMI)Observatory

  15. The Cooperative Institute for Oceanographic Satellite Studies (CIOSS)

    Geosciences Websites

    Kurapov, Alexander

    The Cooperative Institute for Oceanographic Satellite Studies (CIOSS) Year 2 Annual Progress Report: Associate Professor; COAS Dr. Yvette Spitz: Associate Professor; COAS Dr. Peter Strutton: Assistant, OSU #12;1 The Cooperative Institute for Oceanographic Satellite Studies (CIOSS) Year 2 Annual Progress

  16. MAPPING FERRUGINOUS HAWK (BUTEO REGALIS) HABITAT USING SATELLITE DATA

    Biology and Medicine Websites

    Wallin, David O.

    MAPPING FERRUGINOUS HAWK (BUTEO REGALIS) HABITAT USING SATELLITE DATA BY NATALYA V. ANTONOVA _________________________ #12;MAPPING FERRUGINOUS HAWK HABITAT USING SATELLITE DATA A Thesis Presented to The Faculty of Western quality and abundance. One species of special concern is the ferruginous hawk (Buteo regalis), which

  17. Interference Mitigation Techniques for Broadband Satellite L. Cottatellucci*

    Engineering Websites

    Müller, Ralf R.

    , this leads to the utilization of high frequency bands (e.g. the Ka-band) and to the deployment of a large1 Interference Mitigation Techniques for Broadband Satellite Systems L. Cottatellucci capacity of broadband multimedia satellite systems. A multi-star network topology using a bent

  18. Heuristics for Robust Resource Allocation of Satellite Weather Data Processing

    Engineering Websites

    Maciejewski, Anthony A. "Tony"

    Heuristics for Robust Resource Allocation of Satellite Weather Data Processing on a Heterogeneous--This work considers the satellite data processing portion of a space-based weather monitoring system INTRODUCTION THE space-based weather monitoring system considered in this work consists of two major components

  19. Scalable Proportional Allocation of Bandwidth in IP Satellite Networks12

    Computer Technologies and Information Sciences Websites

    Jain, Raj

    December 10, 2002 Abstract--Proposed satellite constellation networks, based on Geostationary Earth Orbit (GEO) satellites, Medium Earth Orbit (MEO), and Low Earth Orbit (LEO) systems, will be required have been filed with FCC [2]. The space segment development has now reached the network layer

  20. Analysis of sampling behavior of candidate SWOT satellite orbits

    Geosciences Websites

    Stuttgart, Universität

    Analysis of sampling behavior of candidate SWOT satellite orbits Sh. Roohi, N. Sneeuw Institute- ficiency. A careful repeat orbit design plays important role in sampling the earth from the space by SWOT satellite. Choice an optimized repeat orbit is a key element for successful establishment of this mission

  1. Hybrid 3D Modeling of Large Landscapes from Satellite Maps

    Computer Technologies and Information Sciences Websites

    Abidi, Mongi A.

    . In this project a 3D hybrid model of the Port Arthur Harbor using satellite imagery and Virtual Reality Modeling ................................................................... 28 6.1 Virtual Reality Model LanguageHybrid 3D Modeling of Large Landscapes from Satellite Maps Project in Lieu of Thesis for Master

  2. Distributed Geo-rectification of Satellite Images using Grid Computing

    Computer Technologies and Information Sciences Websites

    Teo, Yong-Meng

    1 Distributed Geo-rectification of Satellite Images using Grid Computing Y.M. Teo* , S.C. Tay you don't own for compute-intensive applications. Geo-rectification is a process for correcting of the compute- intensive satellite image geo-rectification problem on a cluster grid. We discuss our approach

  3. Short term forecasting of solar radiation based on satellite data

    Power Transmission, Distribution and Plants Websites

    Heinemann, Detlev

    development of the cloud situation is essential for irradiance forecasting. As a measure of cloudiness, cloud satellite data, are calculated from the satellite images. To predict the future cloud index image in a first is derived from the predicted cloud index images with the Heliosat method. Figure 1 gives an overview

  4. RETHINKING SATELLITE BASED SOLAR IRRADIANCE MODELLING R. W. Mueller

    Power Transmission, Distribution and Plants Websites

    Heinemann, Detlev

    (clouds, ozone, water vapour) and the ERS-2/ENVISAT satellites (aerosols). This paper focuses transfer model. The linkage of the clear sky module with the cloud module is also briefly described on statistical methods. They use cloud information from the current METEOSAT or GOES satellite and climatologies

  5. Testing General Relativity and gravitational physics using the LARES satellite

    General Relativity & Quantum Cosmology (arXiv)

    Ignazio Ciufolini; Antonio Paolozzi; Erricos Pavlis; John Ries; Vahe Gurzadyan; Rolf Koenig; Richard Matzner; Roger Penrose; Giampiero Sindoni

    2012-11-06

    The discovery of the accelerating expansion of the Universe, thought to be driven by a mysterious form of `dark energy' constituting most of the Universe, has further revived the interest in testing Einstein's theory of General Relativity. At the very foundation of Einstein's theory is the geodesic motion of a small, structureless test-particle. Depending on the physical context, a star, planet or satellite can behave very nearly like a test-particle, so geodesic motion is used to calculate the advance of the perihelion of a planet's orbit, the dynamics of a binary pulsar system and of an Earth orbiting satellite. Verifying geodesic motion is then a test of paramount importance to General Relativity and other theories of fundamental physics. On the basis of the first few months of observations of the recently launched satellite LARES, its orbit shows the best agreement of any satellite with the test-particle motion predicted by General Relativity. That is, after modelling its known non-gravitational perturbations, the LARES orbit shows the smallest deviations from geodesic motion of any artificial satellite. LARES-type satellites can thus be used for accurate measurements and for tests of gravitational and fundamental physics. Already with only a few months of observation, LARES provides smaller scatter in the determination of several low-degree geopotential coefficients (Earth gravitational deviations from sphericity) than available from observations of any other satellite or combination of satellites.

  6. Title: Satellite Streetview: Prince Edward Island Data Creator /

    Computer Technologies and Information Sciences Websites

    Title: Satellite Streetview: Prince Edward Island Data Creator / Copyright Owner: DMTI Spatial Inc: N/A Abstract: Satellite images generated for cities and/or regions in Prince Edward Island.. Areas: N/A Keywords (Place): Canada; Prince Edward Island; Charlottetown Keywords (Subject): Aerial Images

  7. Title: IKONOS Satellite Image of North York, Ontario Data Creator /

    Computer Technologies and Information Sciences Websites

    Title: IKONOS Satellite Image of North York, Ontario Data Creator / Copyright Owner: GeoEye Publisher: GeoEye Edition: N/A Versions: N/A Publication Date: 2007 Coverage Date(s): July 3, 2007 Updates, Green, Blue bands) image and Panchromatic Satellite image of downtown Toront. It has a resolution of 1

  8. Micro-Electromagnetic Formation Flight of Satellite Systems Aya Sakaguchi

    Engineering Websites

    Micro-Electromagnetic Formation Flight of Satellite Systems by Aya Sakaguchi B.S. Mechanical;3 Micro-Electromagnetic Formation Flight of Satellite Systems by Aya Sakaguchi Submitted to the Department Electromagnetic formation flight (EMFF) investigates the concept of using electromagnets to provide the forces

  9. ForPeerReview Multi-sensor Satellite Remote Sensing of Dust Aerosols over

    Environmental Sciences and Ecology Websites

    Christopher, Sundar A.

    ForPeerReview Multi-sensor Satellite Remote Sensing of Dust Aerosols over North Africa during Keywords: GERBILS, Satellite remote Sensing, Aerosols Quarterly Journal of the Royal Meteorological Society #12;ForPeerReview Satellite Remote Sensing during GERBILS

  10. Geosynchronous satellite maneuver detection and orbit recovery using ground based optical tracking

    MIT - DSpace

    Aaron, Benjamin S. (Benjamin Samuel)

    2006-01-01

    Geosynchronous satellite orbit maintenance is a very important issue. Satellites maneuver frequently requiring the ability to detect unknown maneuvers for target satellites and quickly recover an accurate orbit. This study ...

  11. Anti-cyclonic eddies northwest of Luzon in summerfall observed by satellite altimeters

    Geosciences Websites

    Han, Weiqing

    -fall are identified in the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European the Satellite observations discussed below. 2. Satellite Data [4] The merged products of sea level anomalies

  12. Satellite-based modeling of gross primary production in a seasonally moist tropical evergreen forest

    Environmental Sciences and Ecology Websites

    Saleska, Scott

    -year satellite images from the VEGETATION (VGT) sensor onboard the SPOT-4 satellite (4/1998­12/2002) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite (2000­2003). We reported

  13. Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital

    Engineering Websites

    de Weck, Olivier L.

    Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital Students #12;2 #12;Enhancing the Economics of Satellite Constellations via Staged Deployment and Orbital and Astronautics Abstract The "traditional" way of designing constellations of communications satellites

  14. Channel Estimation and Code Word Inference for Mobile Digital Satellite Broadcasting Reception

    Mathematics Websites

    Ikeda, Shiro

    #12;Channel Estimation and Code Word Inference for Mobile Digital Satellite Broadcasting Reception reception of digital satellite broadcasting in a moving vehicle. According to some studies, the antennas sequences and diversity reception. Digital satellite broadcasting, however, does not transmit pilot

  15. Mark S. Paese Deputy Assistant Administrator for Satellite and Information Services

    Environmental Sciences and Ecology Websites

    Mark S. Paese Deputy Assistant Administrator for Satellite and Information Services Mark Paese serves as the Deputy Assistant Administrator for Satellite and Information Services, National Environmental Satellite, Data, and Information Service (NESDIS), National Oceanic and Atmospheric Administration

  16. Welcome from the CIOSS Director The Cooperative Institute for Oceanographic Satellite Studies (CIOSS) was

    Geosciences Websites

    Kurapov, Alexander

    Welcome from the CIOSS Director The Cooperative Institute for Oceanographic Satellite Studies at the NESDIS STAR Satellite Oceanography and Climatology Division (SOCD) to enhance and improve the use of satellite remote sensing for oceanographic research, operational applications, and education

  17. FPGA Implementation of a Satellite Attitude Control using Variable Structure Control

    Computer Technologies and Information Sciences Websites

    Aboelaze, Mokhtar

    FPGA Implementation of a Satellite Attitude Control using Variable Structure Control Mokhtar Dept. of Electrical Engineering Effat University Jeddah Saudi Arabia Abstract-- Satellite control implementation of a Variable Structure Controller (VSC) for a satellite. Our implementation uses fixed point

  18. INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING Int. J. Satell. Commun. Network. 2006; 24:261281

    Computer Technologies and Information Sciences Websites

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING Int. J. Satell. Commun. Network: 10.1002/sat.841 Turbo-coded APSK modulations design for satellite broadband communications Riccardo phase shift keying (APSK) modulation with application to satellite broadband communications. APSK

  19. Evaluation of mesoscale convective systems in South America using multiple satellite products and an objectbased approach

    Geosciences Websites

    Ebert, Beth

    Evaluation of mesoscale convective systems in South America using multiple satellite products satellite precipitation products: Tropical Rainfall Measurement Mission (TRMM), Climate Prediction Center of all satellite products. Errors in the spatial location of the systems influenced the magnitude

  20. Improved Explicit Congestion Notification for Satellite Networks Arjan Durresi*a

    Computer Technologies and Information Sciences Websites

    Durresi, Arjan

    of the greatest challenges before telecommunications industry in the 21st century. Satellite communicationImproved Explicit Congestion Notification for Satellite Networks Arjan Durresi*a , Mukundan University b Nayna Networks, Inc. ABSTRACT Due to the fundamental satellite system characteristics

  1. Relationship between Cloud Condensation Nuclei and Satellite Retrievals of Cloud Droplet Effective Radius

    Geosciences Websites

    Delene, David J.

    ` Relationship between Cloud Condensation Nuclei and Satellite Retrievals of Cloud Droplet is the relationship between below cloud base cloud condensation nuclei (CCN) and satellite retrievals of cloud droplet cloud effective radius; however, satellites can not measure cloud condensation nuclei (CCN

  2. Dark influences: imprints of dark satellites on dwarf galaxies

    CERN Preprints

    Starkenburg, Tjitske K

    2014-01-01

    In the context of the current $\\Lambda$CDM cosmological model small dark matter haloes are abundant and satellites of dwarf galaxies are expected to be predominantly dark. Since low mass galaxies have smaller baryon fractions interactions with these satellites may leave particularly dramatic imprints. We uncover the influence of the most massive of these dark satellites on disky dwarf galaxies and the possible dynamical and morphological transformations that result from these interactions. We use a suite of carefully set-up, controlled simulations of isolated dwarf galaxies. The primary dwarf galaxies have solely a stellar disk in the dark matter halo and the secundaries are completely devoid of baryons. We vary the disk mass, halo concentration, initial disk thickness and inclination of the satellite orbit. The disky dwarf galaxies are heated and disrupted due to the minor merger event, more extremely for higher satellite over disk mass ratios, and the morphology and kinematics are significantly altered. Mor...

  3. Asymptotic behavior of an elastic satellite with internal friction

    Mathematical Physics (arXiv)

    Emanuele Haus; Dario Bambusi

    2012-12-04

    We study the dynamics of an elastic body whose shape and position evolve due to the gravitational forces exerted by a pointlike planet. The main result is that, if all the deformations of the satellite dissipate some energy, then under a suitable nondegeneracy condition there are only three possible outcomes for the dynamics: (i) the orbit of the satellite is unbounded, (ii) the satellite falls on the planet, (iii) the satellite is captured in synchronous resonance i.e. its orbit is asymptotic to a motion in which the barycenter moves on a circular orbit, and the satellite moves rigidly, always showing the same face to the planet. The result is obtained by making use of LaSalle's invariance principle and by a careful kinematic analysis showing that energy stops dissipating only on synchronous orbits. We also use in quite an extensive way the fact that conservative elastodynamics is a Hamiltonian system invariant under the action of the rotation group.

  4. Submerged turbulence detection with optical satellites

    CERN Preprints

    Gibson, Carl H; Bondur, Valery G; Leung, Pak T; Prandke, H; Vithanage, D

    2007-01-01

    During fall periods in 2002, 2003 and 2004 three major oceanographic expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite images of sea surface glint revealed ~100 m spectral anomalies in km^2 averaging patches in regions leading from the Honolulu Sand Island Municipal Outfall diffuser to distances up to 20 km. To determine the mechanisms behind this phenomenon, the RASP expeditions monitored the waters adjacent to the outfall with an array of hydrographic, optical and turbulence microstructure sensors in anomaly and ambient background regions. Drogue tracks and mean turbulence parameters for 2x10^4 microstructure patches were analyzed to understand complex turbulence, fossil turbulence and zombie turbulence near-vertical internal wave transport processes. The dominant mechanism appears to be generic to stratified natural fluids including planet and star atmospheres and is termed beamed zombie turbulence ma...

  5. The Extended Shapes of Galactic Satellites

    Astrophysics (arXiv)

    S. R. Majewski; A. D. Forestell; J. C. Ostheimer; C. Palma; M. H. Siegel; S. Sohn; K. B. Westfall; R. J. Patterson; P. M. Frinchaboy; R. Link

    2001-09-26

    We are exploring the extended stellar distributions of Galactic satellite galaxies and globular clusters. For seven objects studied thus far, the observed profile departs from a King function at large r, revealing a ``break population'' of stars. In our sample, the relative density of the ``break'' correlates to the inferred M/L of these objects. We discuss opposing hypotheses for this trend: (1) Higher M/L objects harbor more extended dark matter halos that support secondary, bound, stellar ``halos''. (2) The extended populations around dwarf spheroidals (and some clusters) consist of unbound, extratidal debris from their parent objects, which are undergoing various degrees of tidal disruption. In this scenario, higher M/L ratios reflect higher degrees of virial non-equilibrium in the parent objects, thus invalidating a precept underlying the use of core radial velocities to obtain masses.

  6. Symmetric Satellite Swarms and Choreographic Crystals

    CERN Preprints

    Boyle, Latham; Smith, Kendrick

    2014-01-01

    In this paper, we introduce a natural dynamical analogue of crystalline order, which we call choreographic order. In an ordinary (static) crystal, a high degree of symmetry may be achieved through a careful arrangement of the fundamental repeated elements. In the dynamical analogue, a high degree of symmetry may be achieved by having the fundamental elements perform a carefully choreographed dance. For starters, we show how to construct and classify all symmetric satellite constellations. Then we explain how to generalize these ideas to construct and classify choreographic crystals more broadly. We introduce a quantity, called the "choreography" of a given configuration. We discuss the possibility that some (naturally occurring or artificial) many-body or condensed-matter systems may exhibit choreographic order, and suggest natural experimental signatures that could be used to identify and characterize such systems.

  7. Symmetric Satellite Swarms and Choreographic Crystals

    Mathematical Physics (arXiv)

    Latham Boyle; Jun Yong Khoo; Kendrick Smith

    2014-07-22

    In this paper, we introduce a natural dynamical analogue of crystalline order, which we call choreographic order. In an ordinary (static) crystal, a high degree of symmetry may be achieved through a careful arrangement of the fundamental repeated elements. In the dynamical analogue, a high degree of symmetry may be achieved by having the fundamental elements perform a carefully choreographed dance. For starters, we show how to construct and classify all symmetric satellite constellations. Then we explain how to generalize these ideas to construct and classify choreographic crystals more broadly. We introduce a quantity, called the "choreography" of a given configuration. We discuss the possibility that some (naturally occurring or artificial) many-body or condensed-matter systems may exhibit choreographic order, and suggest natural experimental signatures that could be used to identify and characterize such systems.

  8. Constraining supersymmetry from the satellite experiments

    HEP - Phenomenology (arXiv)

    Xiao-Jun Bi

    2007-12-10

    In this paper we study the detectability of $\\gamma$-rays from dark matter annihilation in the subhalos of the Milky Way by the satellite-based experiments, EGRET and GLAST. We work in the frame of supersymmetric extension of the standard model and assume the lightest neutralino being the dark matter particles. Based on the N-body simulation of the evolution of dark matter subhalos we first calculate the average intensity distribution of this new class of $\\gamma$-ray sources by neutralino annihilation. It is possible to detect these $\\gamma$-ray sources by EGRET and GLAST. Conversely, if these sources are not detected the nature of the dark matter particls will be constrained by these experiments, which, however, depending on the uncertainties of the subhalo profile.

  9. Feasibility of satellite quantum key distribution

    Quantum Physics (arXiv)

    Cristian Bonato; Andrea Tomaello; Vania Da Deppo; Giampiero Naletto; Paolo Villoresi

    2009-05-12

    In this paper we present a novel analysis of the feasibility of quantum key distribution between a LEO satellite and a ground station. First of all, we study signal propagation through a turbulent atmosphere for uplinks and downlinks, discussing the contribution of beam spreading and beam wandering. Then we introduce a model for the background noise of the channel during night-time and day-time, calculating the signal-to-noise ratio for different configurations. We also discuss the expected error-rate due to imperfect polarization-compensation in the channel. Finally, we calculate the expected key generation rate of a secure key for different configurations (uplink, downlink) and for different protocols (BB84 with and without decoy states, entanglement-based Ekert91 protocol).

  10. Relative equilibria of four identical satellites

    Mathematical Physics (arXiv)

    Alain Albouy; Yanning Fu

    2009-02-18

    We consider the Newtonian 5-body problem in the plane, where 4 bodies have the same mass m, which is small compared to the mass M of the remaining body. We consider the (normalized) relative equilibria in this system, and follow them to the limit when m/M -> 0. In some cases two small bodies will coalesce at the limit. We call the other equilibria the relative equilibria of four separate identical satellites. We prove rigorously that there are only three such equilibria, all already known after the numerical researches in [SaY]. Our main contribution is to prove that any equilibrium configuration possesses a symmetry, a statement indicated in [CLO2] as the missing key to proving that there is no other equilibrium.

  11. Generalized Morse Potential Symmetry and Satellite Potentials

    CERN Preprints

    Del Sol-Mesa, A; Smirnov, Yu F; Smirnov, Yu. F.

    1998-01-01

    We study in detail the bound state spectrum of the generalized Morse potential~(GMP), which was proposed by Deng and Fan as a potential function for diatomic molecules. By connecting the corresponding Schrödinger equation with the Laplace equation on the hyperboloid and the Schrödinger equation for the an $so(2,2)$ symmetry algebra, and obtain an explicit realization of the latter as $su(1,1) \\oplus su(1,1)$. We prove that some of the $so(2,2)$ generators connect among themselves wave functions belonging to different GMP's (called satellite potentials). The conserved quantity is some combination of the potential parameters instead of the level energy, as for potential algebras. Hence, $so(2,2)$ belongs to a new class of symmetry algebras. We also stress the usefulness of our algebraic results for simplifying the calculation of Frank-Condon factors for electromagnetic transitions between rovibrational levels based on different electronic states.

  12. Downburst Prediction Applications of Meteorological Geostationary Satellites

    CERN Preprints

    Pryor, Kenneth L

    2014-01-01

    A suite of products has been developed and evaluated to assess hazards presented by convective storm downbursts derived from the current generation of Geostationary Operational Environmental Satellite (GOES) (13-15). The existing suite of GOES downburst prediction products employs the GOES sounder to calculate risk based on conceptual models of favorable environmental profiles for convective downburst generation. A diagnostic nowcasting product, the Microburst Windspeed Potential Index (MWPI), is designed to infer attributes of a favorable downburst environment: 1) the presence of large convective available potential energy (CAPE), and 2) the presence of a surface-based or elevated mixed layer with a steep temperature lapse rate and vertical relative humidity gradient. These conditions foster intense convective downdrafts upon the interaction of sub-saturated air in the elevated or sub-cloud mixed layer with the storm precipitation core. This paper provides an updated assessment of the MWPI algorithm, present...

  13. Properties of cluster satellites in hydrodynamical simulations

    Astrophysics (arXiv)

    Giuseppe Tormen; Lauro Moscardini; Naoki Yoshida

    2004-03-04

    We analyze the dynamical and thermal evolution of dark matter and ICM in hydrodynamical Tree-SPH simulations of galaxy clusters. Starting from a sample of 17 high-resolution objects, with virial mass ranging from 3 10^{14} to 1.7 10^{15} M_sun, we follow the build-up of the systems in dark matter and hot gas through the repeated merging of satellites along their merging history trees. We measure the self-bound mass fraction of subhaloes as a function of time after the merging, estimate the satellite mean orbital properties as a function of the mass ratio with the main cluster at merging time, and study the evolution of their internal velocity dispersion, gas temperature and entropy as the substructure is disrupted by various dynamical processes, reaching eventually thermo-dynamic equilibrium in the gravitational potential of the main cluster. We model some relevant properties of subhalo orbits, as the time of the first pericentric and apocentric passages, and the typical distances and velocities at the corresponding times. This survival study can be used to interpret the dynamics of observed merging clusters; as an example we apply our results to the system 1E0657-56. We show that, in the light of our results, the most likely interpretation of the data for this cluster points to the merger of a small group with mass M\\approx 1 10^{13} M_sun with a massive cluster with M\\approx 1.3 10^{15} M_sun.

  14. Use of Thematic Mapper SatelliteUse of Thematic Mapper Satellite Imagery, Hemispherical CanopyImagery, Hemispherical Canopy

    Environmental Sciences and Ecology Websites

    1 Use of Thematic Mapper SatelliteUse of Thematic Mapper Satellite Imagery, Hemispherical CanopyImagery temperature research is important for developing management plans for thermally sensitive species such as bull imagery/DOQimagery/DOQ The study incorporates four important data collection components. We assume

  15. Evaluation of Long-Term Cloud-Resolving Model Simulations Using Satellite Radiance Observations and Multifrequency Satellite Simulators

    Physics Websites

    Masunaga, Hirohiko

    and microphysics in a cloud-resolving model (CRM). T3EF utilizes multisensor satellite simulators and novel and microphysics evolution, CRMs are still subject to many uncertainties in cloud microphysi- cal processes becauseEvaluation of Long-Term Cloud-Resolving Model Simulations Using Satellite Radiance Observations

  16. TriAnd and its Siblings: Satellites of Satellites in the Milky Way Halo

    CERN Preprints

    Deason, A J; Hamren, K M; Koposov, S E; Gilbert, K M; Beaton, R L; Dorman, C E; Guhathakurta, P; Majewski, S R; Cunningham, E C

    2014-01-01

    We explore the Triangulum-Andromeda (TriAnd) overdensity in the SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) and SEGUE (the Sloan Extension for Galactic Understanding and Exploration) spectroscopic surveys. Milky Way main sequence turn-off stars in the SPLASH survey reveal that the TriAnd overdensity and the recently discovered PAndAS stream (Martin et al. 2014) share a common distance (D ~ 20 kpc), position on the sky, and line-of-sight velocity (V_GSR ~ 50 km/s). Similarly, A-type, giant, and main sequence turn-off stars selected from the SEGUE survey in the vicinity of the Segue 2 dwarf show that TriAnd is prevalent in these fields, with a velocity and distance similar to the Segue 2 satellite. The coincidence of the PAndAS stream and Segue 2 satellite in positional and velocity space to TriAnd suggests that these substructures are all associated, and may be a fossil record of group-infall onto the Milky Way halo. In this scenario, the Segue 2 satellite and PAndAS stream are...

  17. Satellite Infall and the Growth of Bulges of Spiral Galaxies

    Astrophysics (arXiv)

    M. C. Eliche-Moral; M. Balcells; J. A. L. Aguerri; A. C. Gonzalez-Garcia

    2005-01-18

    For bulges of spiral galaxies, the concentration, or Sersic index, increases with bulge luminosity and bulge-to-disk ratio B/D (Andredakis, Peletier, & Balcells 1995, MNRAS, 275, 874). Does this trend trace the growth of bulges via satellite accretion? And, is satellite infall consistent with this trend? Aguerri, Balcells, & Peletier (2001, A&A, 367, 428) investigated this question with N-body simulations of the accretion of dense, spheroidal satellites. Here, we expand on that work by running N-body simulations of the accretion of satellites that have realistic densities. Satellites are modelled as disk-bulge structures with their own dark-matter halo. A realistic density scaling with the primary galaxy is ensured by using the Tully-Fisher relation. Our merger models show that most satellites disrupt before reaching the center. However, a bulge-disk decomposition of the surface density profile after the accretion shows an increase of both the B/D and the Sersic index n of the bulge. The increase in the mass and concentration of the inner Sersic component is due to inward piling up of disk material due to transient bars during the satellite orbital decay. This research is described in Eliche-Moral, Balcells, Aguerri, & Gonzalez-Garcia, 2005 (in preparation).

  18. Anisotropic Distribution of SDSS Satellite Galaxies: Planar (not Polar) Alignment

    Astrophysics (arXiv)

    Tereasa G. Brainerd

    2005-06-15

    The distribution of satellite galaxies relative to isolated host galaxies in the Sloan Digital Sky Survey (SDSS) is investigated. Host-satellite systems are selected using three different methods, yielding samples of ~3300, ~1600, and \\~950 satellites. In the plane of the sky, the distributions of all three samples show highly significant deviations from circular symmetry (> 99.99%, > 99.99%, and 99.79% confidence levels, respectively), and the degree of anisotropy is a strong function of the projected radius, r_p, at which the satellites are found. For r_p < 100 kpc, the SDSS satellites are aligned preferentially with the major axes of the hosts. This is in stark contrast to the Holmberg effect, in which satellites are aligned with the minor axes of host galaxies. The degree of anisotropy in the distribution of the SDSS satellites decreases with r_p and is consistent with an isotropic distribution at of order the 1-sigma level for 250 kpc < r_p < 500 kpc.

  19. The Distribution of Satellite Galaxies: The Great Pancake

    Astrophysics (arXiv)

    Noam I Libeskind; Carlos S Frenk; Shaun Cole; John C Helly; Adrian Jenkins; Julio F Navarro; Chris Power

    2005-03-18

    The 11 known satellite galaxies within 250 kpc of the Milky Way lie close to a great circle on the sky. We use high resolution N-body simulations of galactic dark matter halos to test if this remarkable property can be understood within the context of the cold dark matter cosmology. We construct halo merger trees from the simulations and use a semianalytic model to follow the formation of satellite galaxies. We find that in all 6 of our simulations, the 11 brightest satellites are indeed distributed along thin, disk-like structures analogous to that traced by the Milky Way's satellites. This is in sharp contrast to the overall distributions of dark matter in the halo and of subhalos within it which, although triaxial, are not highly aspherical. We find that the spatial distribution of satellites is significantly different from that of the most massive subhalos but is similar to that of the subset of subhalos that had the most massive progenitors at earlier times. The elongated disk-like structure delineated by the satellites has its long axis aligned with the major axis of the dark matter halo. We interpret our results as reflecting the preferential infall of satellites along the spines of a few filaments of the cosmic web.

  20. A Survey of Satellite Galaxies around NGC 4258

    CERN Preprints

    Spencer, Meghin; Yoachim, Peter

    2014-01-01

    We conduct a survey of satellite galaxies around the nearby spiral NGC 4258 by combining spectroscopic observations from the Apache Point Observatory 3.5-meter telescope with SDSS spectra. New spectroscopy is obtained for 15 galaxies. Of the 47 observed objects, we categorize 8 of them as probable satellites, 8 as possible satellites, and 17 as unlikely to be satellites. We do not speculate on the membership of the remaining 14 galaxies due to a lack of velocity and distance information. Radially integrating our best fit NFW profile for NGC 4258 yields a total mass of 1.8e12 Msun within 200 kpc. We find that the angular distribution of the satellites appears to be random, and not preferentially aligned with the disk of NGC 4258. In addition, many of the probable satellite galaxies have blue u-r colors and appear to be star-forming irregulars in SDSS images; this stands in contrast to the low number of blue satellites in the Milky Way and M31 systems at comparable distances.

  1. LARES succesfully launched in orbit: satellite and mission description

    General Relativity & Quantum Cosmology (arXiv)

    Antonio Paolozzi; Ignazio Ciufolini

    2013-05-29

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation system. The data exploitation phase started immediately after the launch under a new contract between ASI and those universities. Tracking of the satellite is provided by the International Laser Ranging Service. Due to its particular design, LARES is the orbiting object with the highest known mean density in the solar system. In this paper, it is shown that this peculiarity makes it the best proof particle ever manufactured. Design aspects, mission objectives and preliminary data analysis will be also presented.

  2. Lasers for coherent optical satellite links with large dynamics

    CERN Preprints

    Chiodo, Nicola; Acef, Ouali; Clairon, Andre; Wolf, Peter

    2013-01-01

    We present the experimental realization of a laser system for ground to satellite optical Doppler ranging at the atmospheric turbulence limit. Such a system needs to display good frequency stability (a few parts in 10^{-14}) whilst allowing large and well controlled frequency sweeps of +/- 12 GHz at rates exceeding 100 MHz/s. Furthermore it needs to be sufficiently compact and robust for transportation to different astronomical observation sites where it is to be interfaced with satellite ranging telescopes. We demonstrate that our system fulfills those requirements and should therefore allow operation of ground to low Earth orbit satellite coherent optical links limited only by atmospheric turbulence.

  3. Core-satellite Graphs. Clustering, Assortativity and Spectral Properties

    CERN Preprints

    Estrada, Ernesto

    2015-01-01

    Core-satellite graphs (sometimes referred to as generalized friendship graphs) are an interesting class of graphs that generalize many well known types of graphs. In this paper we show that two popular clustering measures, the average Watts-Strogatz clustering coefficient and the transitivity index, diverge when the graph size increases. We also show that these graphs are disassortative. In addition, we completely describe the spectrum of the adjacency and Laplacian matrices associated with core-satellite graphs. Finally, we introduce the class of generalized core-satellite graphs, and we analyze the spectral properties of such graphs.

  4. Andean terraced hills (a use of satellite imagery)

    CERN Preprints

    Sparavigna, Amelia Carolina

    2010-01-01

    The aim of this paper is in stimulating the use of satellite imagery, in particular the free service of Google Maps, to investigate the distribution of the agricultural technique of terraced hills in Andean countries, near Titicaca Lake. In fact, satellite maps can give a clear view of the overall surface modified by human work, being then a precious help for on-site archaeological researches and for historical analysis. Satellite imagery is also able to give the distribution of burial and worship places. The paper discusses some examples near the Titicaca Lake.

  5. From Tidal Dwarf Galaxies to Satellite Galaxies

    CERN Preprints

    Duc, F B P A

    2006-01-01

    Cosmological models have granted dwarf galaxies a key role: their properties constrain the distribution of dark matter and the physical evolution of their hosts. There is increasing evidence that objects with masses of dwarf galaxies form in the tidal tails of colliding galaxies and speculations that they could become satellite-like galaxies around their progenitors and thus be cosmologically important. Yet, whether these "Tidal Dwarf Galaxies" (TDGs) candidates are really long-lived and not only present in young interacting systems is still an open question to which numerical simulations may give answers. We present a set of 96 simulations of colliding galaxies with various mass ratios and encounter geometries, and statistically study the evolution of their TDG candidates. Among the 593 substructures initially identified in tidal tails, about 75% fall back onto their progenitor or are disrupted in a few 10^8 years. The remaining 25% become long-lived bound objects that typically survive more than 2Gyr with m...

  6. Tidal gravitational effects in a satellite

    CERN Preprints

    Tourrenc, P; Ovido, X; Tourrenc, Philippe; Angonin-Willaime, Marie-Christine; Ovido, Xavier

    2004-01-01

    Atomic wave interferometers are tied to a telescope pointing towards a faraway star in a nearly free falling satellite. Such a device is sensitive to the acceleration and the rotation relatively to the local inertial frame and to the tidal gravitational effects too. We calculate the rotation of the telescope due to the aberration and the deflection of the light in the gravitational field of a central mass (the Earth and Jupiter). Within the framework of a general parametrized description of the problem, we discuss the contributions which must be taken into account in order to observe the Lense-Thirring effect. Using a geometrical model, we consider some perturbations to the idealized device and we calculate the corresponding effect on the periodic components of the signal. Some improvements in the knowledge of the gravitational field are still necessary as well as an increase of the experimental capabilities; however our conclusions support a reasonable optimism for the future. Finally we put forward the nece...

  7. Generalized Morse Potential: Symmetry and Satellite Potentials

    Mathematical Physics (arXiv)

    A. Del Sol Mesa; C. Quesne; Yu. F. Smirnov

    1997-08-06

    We study in detail the bound state spectrum of the generalized Morse potential~(GMP), which was proposed by Deng and Fan as a potential function for diatomic molecules. By connecting the corresponding Schr\\"odinger equation with the Laplace equation on the hyperboloid and the Schr\\"odinger equation for the P\\"oschl-Teller potential, we explain the exact solvability of the problem by an $so(2,2)$ symmetry algebra, and obtain an explicit realization of the latter as $su(1,1) \\oplus su(1,1)$. We prove that some of the $so(2,2)$ generators connect among themselves wave functions belonging to different GMP's (called satellite potentials). The conserved quantity is some combination of the potential parameters instead of the level energy, as for potential algebras. Hence, $so(2,2)$ belongs to a new class of symmetry algebras. We also stress the usefulness of our algebraic results for simplifying the calculation of Frank-Condon factors for electromagnetic transitions between rovibrational levels based on different electronic states.

  8. Tidal gravitational effects in a satellite

    General Relativity & Quantum Cosmology (arXiv)

    Philippe Tourrenc; Marie-Christine Angonin-Willaime; Xavier Ovido

    2004-07-23

    Atomic wave interferometers are tied to a telescope pointing towards a faraway star in a nearly free falling satellite. Such a device is sensitive to the acceleration and the rotation relatively to the local inertial frame and to the tidal gravitational effects too. We calculate the rotation of the telescope due to the aberration and the deflection of the light in the gravitational field of a central mass (the Earth and Jupiter). Within the framework of a general parametrized description of the problem, we discuss the contributions which must be taken into account in order to observe the Lense-Thirring effect. Using a geometrical model, we consider some perturbations to the idealized device and we calculate the corresponding effect on the periodic components of the signal. Some improvements in the knowledge of the gravitational field are still necessary as well as an increase of the experimental capabilities; however our conclusions support a reasonable optimism for the future. Finally we put forward the necessity of a more complete, realistic and powerful model in order to obtain a definitive conclusion on the feasibility of the experiment as far as the observation of the Lense-Thirring effect is involved.

  9. Astrometric Microlensing with the GAIA satellite

    Astrophysics (arXiv)

    V. A. Belokurov; N. W. Evans

    2001-12-11

    GAIA is the ``super-Hipparcos'' survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is about 10^{-5}. Some 25000 sources will have a significant variation of the centroid shift, together with a closest approach, during the lifetime of the mission. A covariance analysis is used to study the propagation of errors and the estimation of parameters from realistic sampling of the GAIA datastream of transits in the along-scan direction during microlensing events. Monte Carlo simulations are used to study the 2500 events for which the mass can be recovered with an error of less than 50 per cent. These high quality events are dominated by disk lenses within a few tens of parsecs and source stars within a few hundred parsecs. We show that the local mass function can be recovered from the high quality sample to good accuracy. GAIA is the first instrument with the capabilities of measuring the mass locally in very faint objects like black holes and very cool white and brown dwarfs. For only 5 per cent of all astrometric events will GAIA record even one photometric datapoint. There is a need for a dedicated telescope that densely samples the Galactic Centre and spiral arms, as this can improve the accuracy of parameter estimation by a factor of about 10.

  10. The population of natural Earth satellites

    CERN Preprints

    Granvik, Mikael; Jedicke, Robert

    2011-01-01

    We have for the first time calculated the population characteristics of the Earth's irregular natural satellites (NES) that are temporarily captured from the near-Earth-object (NEO) population. The steady-state NES size-frequency and residence-time distributions were determined under the dynamical influence of all the massive bodies in the solar system (but mainly the Sun, Earth, and Moon) for NEOs of negligible mass. To this end, we compute the NES capture probability from the NEO population as a function of the latter's heliocentric orbital elements and combine those results with the current best estimates for the NEO size-frequency and orbital distribution. At any given time there should be at least one NES of 1-meter diameter orbiting the Earth. The average temporarily-captured orbiter (TCO; an object that makes at least one revolution around the Earth in a co-rotating coordinate system) completes $(2.88\\pm0.82)\\rev$ around the Earth during a capture event that lasts $(286\\pm18)\\days$. We find a small pre...

  11. Submerged turbulence detection with optical satellites

    Astrophysics (arXiv)

    Carl H. Gibson; R. Norris Keeler; Valery G. Bondur; Pak T. Leung; H. Prandke; D. Vithanage

    2007-09-05

    During fall periods in 2002, 2003 and 2004 three major oceanographic expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite images of sea surface glint revealed ~100 m spectral anomalies in km^2 averaging patches in regions leading from the Honolulu Sand Island Municipal Outfall diffuser to distances up to 20 km. To determine the mechanisms behind this phenomenon, the RASP expeditions monitored the waters adjacent to the outfall with an array of hydrographic, optical and turbulence microstructure sensors in anomaly and ambient background regions. Drogue tracks and mean turbulence parameters for 2x10^4 microstructure patches were analyzed to understand complex turbulence, fossil turbulence and zombie turbulence near-vertical internal wave transport processes. The dominant mechanism appears to be generic to stratified natural fluids including planet and star atmospheres and is termed beamed zombie turbulence maser action (BZTMA). Most of the bottom turbulent kinetic energy is converted to ~100 m fossil turbulence waves. These activate secondary (zombie) turbulence in outfall fossil turbulence patches that transmit heat, mass, chemical species, momentum and information vertically to the sea surface for detection in an efficient maser action. The transport is beamed in intermittent mixing chimneys.

  12. The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem

    Astrophysics (arXiv)

    Joshua D. Simon; Marla Geha

    2007-07-26

    We present Keck/DEIMOS spectroscopy of stars in 8 of the newly discovered ultra-faint dwarf galaxies around the Milky Way. We measure the velocity dispersions of Canes Venatici I and II, Ursa Major I and II, Coma Berenices, Hercules, Leo IV and Leo T from the velocities of 18 - 214 stars in each galaxy and find dispersions ranging from 3.3 to 7.6 km/s. The 6 galaxies with absolute magnitudes M_V < -4 are highly dark matter-dominated, with mass-to-light ratios approaching 1000. The measured velocity dispersions are inversely correlated with their luminosities, indicating that a minimum mass for luminous galactic systems may not yet have been reached. We also measure the metallicities of the observed stars and find that the 6 brightest of the ultra-faint dwarfs extend the luminosity-metallicity relationship followed by brighter dwarfs by 2 orders of magnitude in luminosity; several of these objects have mean metallicities as low as [Fe/H] = -2.3 and therefore represent some of the most metal-poor known stellar systems. We detect metallicity spreads of up to 0.5 dex in several objects, suggesting multiple star formation epochs. Having established the masses of the ultra-faint dwarfs, we re-examine the missing satellite problem. After correcting for the sky coverage of the SDSS, we find that the ultra-faint dwarfs substantially alleviate the discrepancy between the predicted and observed numbers of satellites around the Milky Way, but there are still a factor of ~4 too few dwarf galaxies over a significant range of masses. We show that if galaxy formation in low-mass dark matter halos is strongly suppressed after reionization, the simulated circular velocity function of CDM subhalos can be brought into approximate agreement with the observed circular velocity function of Milky Way satellite galaxies. [slightly abridged

  13. Formation of dSph Satellites without Dark Matter

    CERN Preprints

    Kroupa, P

    1998-01-01

    Recently it was shown that low-mass galaxies containing no dark matter can naturally evolve to dSph-like satellites in a tidal field. Such dSph-like satellites fake total domination by dark matter. If this is correct then it must be possible to assemble appropriate precursors of dSph satellites. The genesis of dwarf galaxies in tidal tails appears to be a likely possibility. This is documented by theoretical work and observational surveys. However, it is not yet clear if the Milky Way could have sustained one or two mergers or fly-bys that were mild enough not to have destroyed the Galactic disc. The tidal arms could have been pulled from the incoming galaxy. Also, this scenario has to account for the correlation between brightness and metal abundance displayed by the Galactic dSph satellites, and lead to at least some debris on bound eccentric orbits.

  14. The Fundamental Line of the Local Group Satellites

    Astrophysics (arXiv)

    Francisco Prada; Andreas Burkert

    2001-08-17

    We present a new correlation between the mass-to-light (M/L) ratio and the mean metallicity for the satellites of the Local Group. This relation together with their central surface brightness define a Fundamental Line where metal poor and low surface brightness dwarfs are dark matter dominated while metal rich high surface brightness systems will have a low M/L ratio. This Fundamental Line is independent of distance to the central galaxy (M31 and the Milky Way) and morphological type among other global parameters as their star formation history. The new M/L-metallicity relation indicates that dwarf spheroidal galaxies are dark matter confined. It can be interpreted if satellites experienced a continuous loss of metals with a final episode of gas ejection at the end of the star formation epoch. Only Globular Clusters are found to lie outside the Fundamental Line of dwarf satellites. Unlike satellite galaxies they are not dark matter confined.

  15. Micro-electromagnetic formation flight of satellite systems

    MIT - DSpace

    Sakaguchi, Aya, S.M. Massachusetts Institute of Technology

    2007-01-01

    Electromagnetic formation flight (EMFF) investigates the concept of using electromagnets to provide the forces to maintain a satellite's relative position in a formation. Thus far, high temperature superconducting (HTS) ...

  16. Satellite Galaxies and Fossil Groups in the Millennium Simulation

    CERN Preprints

    Sales, L V; Lambas, D G; White, S D M; Croton, D J

    2007-01-01

    We use a semianalytic galaxy catalogue constructed from the Millennium Simulation to study the satellites of isolated galaxies in the LCDM cosmogony. This sample (~80,000$ bright primaries, surrounded by ~178,000 satellites) allows the characterization, with minimal statistical uncertainty, of the dynamical properties of satellite/primary galaxy systems in a LCDM universe. We find that, overall, the satellite population traces the dark matter rather well: its spatial distribution and kinematics may be approximated by an NFW profile with a mildly anisotropic velocity distribution. Their spatial distribution is also mildly anisotropic, with a well-defined ``anti-Holmberg'' effect that reflects the misalignment between the major axis and angular momentum of the host halo. The isolation criteria for our primaries picks not only galaxies in sparse environments, but also a number of primaries at the centre of ''fossil'' groups. We find that the abundance and luminosity function of these unusual systems are in reaso...

  17. Reconstructing the assembly of the Milky Way dwarf satellite population

    CERN Preprints

    Rashkov, Valery; Kuhlen, Michael; Diemand, Jurg

    2011-01-01

    We use a particle tagging technique to dynamically populate the N-body Via Lactea II high-resolution simulation with stars. The method is calibrated using the observed luminosity function of Milky Way satellites and the concentration of their stellar populations, and self-consistently follows the accretion and disruption of progenitor dwarfs and the build-up of the stellar halo in a cosmological "live host". Simple prescriptions for assigning stellar populations to collisionless particles are able to reproduce many properties of the observed Milky Way halo and its surviving dwarf satellites, like velocity dispersions, sizes, brightness profiles, metallicities, and spatial distribution. Our model predicts the existence of approximately 1,850 "extremely faint" satellites (with mass-to-light ratios >5,000) lying beyond the Sloan Digital Sky Survey detection threshold. Of these, about 20 are "first galaxies", i.e. satellites that formed a stellar mass above 10 Msun before redshift 9. The ten most luminous satelli...

  18. Multi-stakeholder Interactive Simulation for Federated Satellite Systems

    MIT - DSpace

    Grogan, Paul Thomas

    Federated satellite systems (FSS) are a new class of space-based systems which emphasize a distributed architecture. New information exchanging functions among FSS members enable data transportation, storage, and processing ...

  19. Search for Dark Matter Satellites using the FERMI-LAT

    CERN Preprints

    Ackermann, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bottacini, E; Brandt, T J; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; de Palma, F; Dermer, C D; Digel, S W; Silva, E do Couto e; Drell, P S; Drlica-Wagner, A; Essig, R; Falletti, L; Favuzzi, C; Fegan, S J; Focke, W B; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Guiriec, S; Gustafsson, M; Hadasch, D; Hayashida, M; Hou, X; Hughes, R E; Johnson, R P; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Knodlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S -H; Lionetto, A M; Garde, M Llena; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Naumann-Godo, M; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Pelassa, V; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Raino, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Sadrozinski, H F -W; Sehgal, N; Sgro, C; Siskind, E J; Spinelli, P; Strigari, L; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J G; Thayer, J B; Tibaldo, L; Tinivella, M; Torres, D F; Troja, E; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Yang, Z; Zalewski, S; Zimmer, S

    2012-01-01

    Numerical simulations based on the Lambda-CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the gamma-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on gamma-ray spectra consistent with WIMP annihilation through the $b \\bar b$ channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the $b \\bar b$ channel.

  20. On the use of Satellite Television in High Energy Physics

    CERN Preprints

    Taylor, L; Taylor, Lucas; Williams, David O.

    1998-01-01

    This paper assesses the feasibility of exploiting commercial satellite television technologies to broadcast video signals and data from major High Energy Physics facilities to collaborating institutes throughout the world.

  1. Central configurations of the planar coorbital satellite problem

    Mathematics Websites

    Politècnica de Catalunya, Universitat

    approximation) the motion of several coorbital satellites located in the same circular orbit. In fact, this problem was first consider by Maxwell [19] trying to construct a model for Saturn's rings. The unpublished

  2. KA-BROADBAND SATELLITE COMMUNICATION USING CYCLOSTATIONARY PARABOLIC BEAMFORMING

    Engineering Websites

    Blostein, Steven D.

    life will always be remem- bered. Thoughts of her will forever bring our family closer together for Military Satellite Communications : : : : : : : : 7 2.1.2 Performance of Contour Shaped Beam Antennas

  3. Achieving bounded delay on a time-varying satellite uplink

    MIT - DSpace

    Wysocarski, Jeffrey S.

    In this paper, we investigate the packet transmission delay in a time varying satellite uplink. Specifically, we are interested in bounding the packet transmission delay within the terminal router for uplink traffic in a ...

  4. How environment drives galaxy evolution: lessons learnt from satellite galaxies

    CERN Preprints

    Pasquali, A

    2015-01-01

    It is by now well established that galaxy evolution is driven by intrinsic and environmental processes, both contributing to shape the observed properties of galaxies. A number of early studies, both observational and theoretical, have shown that the star formation activity of galaxies depends on their environmental local density and also on galaxy hierarchy, i.e. centrals vs. satellites. In fact, contrary to their central (most massive) galaxy of a group/cluster, satellite galaxies are stripped of their gas and stars, and have their star formation quenched by their environment. Large galaxy surveys like SDSS now permit us to investigate in detail environment-driven transformation processes by comparing centrals and satellites. In this paper I summarize what we have so far learnt about environmental effects by analysing the observed properties of local central and satellite galaxies in SDSS, as a function of their stellar mass and the dark matter mass of their host group/cluster.

  5. Dynamic resource allocation DAMA alternatives study for satellite communications systems

    MIT - DSpace

    Yao, Huan

    We consider the design of demand assigned multiple access (DAMA) algorithms that efficiently utilize limited RF uplink resources for packet switched military satellite communication networks. In previous work, we designed ...

  6. The Elemental Abundance Distributions of Milky Way Satellite Galaxies

    CERN Preprints

    Kirby, Evan N

    2010-01-01

    The chemical compositions of the stars in Milky Way (MW) satellite galaxies reveals the history of gas flows and star formation (SF) intensity. This talk presented a Keck/DEIMOS spectroscopic survey of the Fe, Mg, Si, Ca, and Ti abundances of nearly 3000 red giants in eight MW dwarf satellites. The metallicity and alpha-to-iron ratio distributions obey the following trends: (1) The more luminous galaxies are more metal-rich, indicating that they retained gas more efficiently than the less luminous galaxies. (2) The shapes of the metallicity distributions of the more luminous galaxies require gas infall during their SF lifetimes. (3) At [Fe/H] < -1.5, [alpha/Fe] falls monotonically with increasing [Fe/H] in all MW satellites. One interpretation of these trends is that the SF timescale in any MW satellite is long enough that Type Ia supernovae exploded for nearly the entire SF lifetime.

  7. A small satellite preliminary thermal control and heat shield analysis

    MIT - DSpace

    Melani Barreiro, Diego A

    2008-01-01

    As part of a student owned small satellite project, a preliminary thermal control and heat shield analysis was developed to verify acceptable performance requirements for the system. For the thermal control section, the ...

  8. Satellite constellation design for mid-course ballistic missile intercept

    MIT - DSpace

    Sauter, Luke Michael, 1979-

    2004-01-01

    This thesis will establish a conceptual approach to the design of constellations for satellite-based mid-course missile defense. The ballistic missile intercept problem leads to a new paradigm of coverage where interceptor ...

  9. The colours of satellite galaxies in the Illustris simulation

    MIT - DSpace

    Sales, Laura V.

    Observationally, the fraction of blue satellite galaxies decreases steeply with host halo mass, and their radial distribution around central galaxies is significantly shallower in massive (M[subscript *] ? 10[superscript ...

  10. Search for Dark Matter Satellites using the FERMI-LAT

    HEP - Experiment (arXiv)

    The Fermi LAT Collaboration; M. Ackermann; A. Albert; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; E. Bottacini; T. J. Brandt; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; T. H. Burnett; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; C. Cecchi; E. Charles; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; S. Cutini; F. de Palma; C. D. Dermer; S. W. Digel; E. do Couto e Silva; P. S. Drell; A. Drlica-Wagner; R. Essig; L. Falletti; C. Favuzzi; S. J. Fegan; W. B. Focke; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; S. Germani; N. Giglietto; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; I. A. Grenier; S. Guiriec; M. Gustafsson; D. Hadasch; M. Hayashida; X. Hou; R. E. Hughes; R. P. Johnson; A. S. Johnson; T. Kamae; H. Katagiri; J. Kataoka; J. Knodlseder; M. Kuss; J. Lande; L. Latronico; S. -H. Lee; A. M. Lionetto; M. Llena Garde; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; M. N. Mazziotta; J. E. McEnery; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; M. Naumann-Godo; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; V. Pelassa; M. Pierbattista; F. Piron; G. Pivato; T. A. Porter; S. Raino; R. Rando; M. Razzano; A. Reimer; O. Reimer; S. Ritz; H. F. -W. Sadrozinski; N. Sehgal; C. Sgro; E. J. Siskind; P. Spinelli; L. Strigari; D. J. Suson; H. Tajima; H. Takahashi; T. Tanaka; J. G. Thayer; J. B. Thayer; L. Tibaldo; M. Tinivella; D. F. Torres; E. Troja; Y. Uchiyama; T. L. Usher; J. Vandenbroucke; V. Vasileiou; G. Vianello; V. Vitale; A. P. Waite; P. Wang; B. L. Winer; K. S. Wood; Z. Yang; S. Zalewski; S. Zimmer

    2012-01-12

    Numerical simulations based on the Lambda-CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the gamma-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on gamma-ray spectra consistent with WIMP annihilation through the $b \\bar b$ channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the $b \\bar b$ channel.

  11. Formation of dSph Satellites without Dark Matter

    Astrophysics (arXiv)

    Pavel Kroupa

    1998-01-07

    Recently it was shown that low-mass galaxies containing no dark matter can naturally evolve to dSph-like satellites in a tidal field. Such dSph-like satellites fake total domination by dark matter. If this is correct then it must be possible to assemble appropriate precursors of dSph satellites. The genesis of dwarf galaxies in tidal tails appears to be a likely possibility. This is documented by theoretical work and observational surveys. However, it is not yet clear if the Milky Way could have sustained one or two mergers or fly-bys that were mild enough not to have destroyed the Galactic disc. The tidal arms could have been pulled from the incoming galaxy. Also, this scenario has to account for the correlation between brightness and metal abundance displayed by the Galactic dSph satellites, and lead to at least some debris on bound eccentric orbits.

  12. An integrated evolutionary model approach to small satellite engineering

    MIT - DSpace

    Robinson, Joseph B. (Joseph Brian)

    2010-01-01

    A deficiency exists in the use of detailed integrated modeling in the design, fabrication, and operations of small satellites (<180kg). This need led to the design of the Integrated Evolutionary Model (IEM) approach to ...

  13. Risk management of student-run small satellite programs

    MIT - DSpace

    Deems, Elizabeth (Elizabeth Carolina)

    2007-01-01

    This paper proposes an approach for failure mode identification in university-affiliated, small satellite programs. These small programs have a unique set of risks due to many factors, including a typically inexperienced ...

  14. Title: Geoeye Satellite Image of North York, Ontario Data Creator /

    Computer Technologies and Information Sciences Websites

    Eye Publisher: GeoEye Edition: N/A Versions: N/A Publication Date: 2009 Coverage Date(s): September 1, 2009 satellite, with the dynamic range adjustment turned off to maintain absolute radiometric accuracy

  15. Upper-bounding bias errors in satellite navigation

    CERN Preprints

    Iwamoto, Takashi

    2014-01-01

    A satellite navigation system for a safety critical application is required to provide an integrity alert of any malfunction; the probability that a navigation positioning error exceeds a given alert limit without an integrity alert is required to be smaller than a given integrity risk. So far, a little number of applications provide integrity alerts, because signal propagation from a satellite to a receiver depends on diversified phenomena and makes probabilistic upper-bound of possible threats difficult. To widen application fields of satellite navigation, two methods to upper-bound wide classes of bias errors are shown in this paper. The worst bias error in a maximum likelihood estimate caused by an interference signal within a given small power is derived. A novel inequality condition with a clock bias error and magnification coefficients that upper-bounds a horizontal position error is presented. Robustness of the inequality condition is numerically shown based on actual configurations of satellites.

  16. Joint ranging and clock synchronization for a satellite array

    Computer Technologies and Information Sciences Websites

    Langendoen, Koen

    : ·Ionosphere is turbulent (10s) ·Calibration changes as a function of position Ionospheric problems §Ionosphere, the ionosphere is opaque: need to be in space! §Design a formation of 50 satellites that correlate their signals

  17. Aerospace Power & Electronics Simulation Workshop 2004 Satellite Attitude Control

    Computer Technologies and Information Sciences Websites

    Simon, Dan

    Aerospace Power & Electronics Simulation Workshop 2004 · Satellite Attitude Control System Design Using Reaction Wheels Bhanu Gouda Brian Fast Dan Simon #12;2Aerospace Power & Electronics Simulation;3Aerospace Power & Electronics Simulation Workshop 2004 ADCS ·ADCS: Attitude Determination and Control

  18. On the use of Satellite Television in High Energy Physics

    HEP - Experiment (arXiv)

    Lucas Taylor; David O. Williams

    1998-10-24

    This paper assesses the feasibility of exploiting commercial satellite television technologies to broadcast video signals and data from major High Energy Physics facilities to collaborating institutes throughout the world.

  19. A Constrained Attitude Control Module for Small Satellites

    Engineering Websites

    Lightsey, Glenn

    The University of Texas at Austin Small Satellite Conference Logan, Utah August 14, 2012 #12;Motivation Common&C Module being assembled Right: Front and back of the flight cold- gas thruster module #12;6 Traditional

  20. The use of satellite-based technology in developing countries

    MIT - DSpace

    Wood, Danielle Renee

    2007-01-01

    Satellite technology in the areas of remote sensing, communication, and navigation can provide valuable information in a number of areas from business to disaster management to agriculture. There is great potential for ...

  1. Satellite Remote Sensing of Mid-level Clouds 

    Texas A&M University - TxSpace

    Jin, Hongchun 1980-

    2012-11-07

    This dissertation aims to study the mid-level clouds using satellite observations. It consists of two major parts: characteristics (including cloud top/base heights, cloud top pressure and temperature, and cloud thickness) and thermodynamic phase...

  2. Astrium Satellites UK Lunar Polar Lander meeting, RAS

    Geosciences Websites

    Anand, Mahesh

    Astrium Satellites UK Lunar Polar Lander meeting, RAS Matthew Stuttard Science & Robotic Divisions of Astrium Stevenage: Spacecraft Systems and Prime Planetary surface robotics Structures - MARVEL MoonLITE Science: Lunar Beagle Science: LVRAP Planetary Surface Robotics Sampling 19

  3. Entanglement over global distances via quantum repeaters with satellite links

    Quantum Physics (arXiv)

    K. Boone; J. -P. Bourgoin; E. Meyer-Scott; K. Heshami; T. Jennewein; C. Simon

    2014-10-20

    We study entanglement creation over global distances based on a quantum repeater architecture that uses low-earth orbit satellites equipped with entangled photon sources, as well as ground stations equipped with quantum non-demolition detectors and quantum memories. We show that this approach allows entanglement creation at viable rates over distances that are inaccessible via direct transmission through optical fibers or even from very distant satellites.

  4. Satellite Accretion Onto Massive Galaxies With Central Black Holes

    Astrophysics (arXiv)

    Michael Boylan-Kolchin; Chung-Pei Ma

    2006-11-17

    Minor mergers of galaxies are expected to be common in a hierarchical cosmology such as $\\Lambda$CDM and have the potential to significantly affect galactic structure. In this paper we dissect the case-by-case outcome from a set of numerical simulations of a single satellite elliptical galaxy accreting onto a massive elliptical galaxy. We take care to explore cosmologically relevant orbital parameters and to set up realistic initial galaxy models that include all three relevant dynamical components: dark matter halos, stellar bulges, and central massive black holes. The effects of several different parameters are considered, including orbital energy and angular momentum, satellite density and inner density profile, satellite-to-host mass ratio, and presence of a black hole at the center of the host. Black holes play a crucial role in protecting the shallow stellar cores of the hosts, as satellites merging onto a host with a central black hole are more strongly disrupted than those merging onto hosts without black holes. Orbital parameters play an important role in determining the degree of disruption: satellites on less bound or more eccentric orbits are more easily destroyed than those on more bound or more circular orbits as a result of an increased number of pericentric passages and greater cumulative effects of gravitational shocking and tidal stripping. In addition, satellites with densities typical of faint elliptical galaxies are disrupted relatively easily, while denser satellites can survive much better in the tidal field of the host. Over the range of parameters explored, we find that the accretion of a single satellite elliptical galaxy can result in a broad variety of changes, in both signs, in the surface brightness profile and color of the central part of an elliptical galaxy.

  5. The Effect of Satellite Galaxies on Gravitational Lensing Flux Ratios

    Astrophysics (arXiv)

    E. M. Shin; N. W. Evans

    2008-01-16

    Gravitational lenses with anomalous flux ratios are often cited as possible evidence for dark matter satellites predicted by simulations of hierarchical merging in cold dark matter cosmogonies. We show that the fraction of quads with anomalous flux ratios depends primarily on the total mass and spatial extent of the satellites, and the characteristic lengthscale R of their distribution. If R is 100 kpc, then for a moderately elliptical galaxy with a line-of-sight velocity dispersion of 250 km/s, a mass of 3 x 10^9 solar masses in highly-concentrated (Plummer model) satellites is needed for 20% of quadruplets to show anomalous flux ratios, rising to 1.25 x 10^10 solar masses for 50%. Several times these masses are required if the satellites have more extended Hernquist profiles. Compared to a typical elliptical, the flux ratios of quads formed by typical edge-on disc galaxies with maximum discs are significantly less susceptible to changes through substructure -- three times the mass in satellite galaxies is needed to affect 50% of the systems. In many of the lens systems with anomalous flux ratios, there is evidence for visible satellites (e.g., B2045+265 or MG0414+0534). We show that optically identified substructure should not be preponderant among lens systems with anomalies. There are two possible resolutions of this difficulty. First, in some cases, visible substructure may be projected within or close to the Einstein radius and wrongly ascribed as the culprit, whereas dark matter substructure is causing the flux anomaly. Second, bright satellites, in which baryon cooling and condensation has taken place, may have higher central densities than dark satellites, rendering them more efficient at causing flux anomalies.

  6. Dwarf-spheroidal satellites: are they of tidal origin?

    CERN Preprints

    Metz, M; 10.1111/j.1365-2966.2007.11438.x

    2008-01-01

    The Milky Way and Andromeda must have formed through an initial epoch of sub-structure merging. As a result of fundamental physical conservation laws tidal-dwarf galaxies (TDGs) have likely been produced. Here we show that such TDGs appear, after a Hubble-time of dynamical evolution in the host dark-matter halo, as objects that resemble known dSph satellite galaxies. We discuss the possibility that some of the Milky Way's satellites may be of tidal origin.

  7. Dwarf-spheroidal satellites: are they of tidal origin?

    Astrophysics (arXiv)

    M. Metz; P. Kroupa

    2007-01-10

    The Milky Way and Andromeda must have formed through an initial epoch of sub-structure merging. As a result of fundamental physical conservation laws tidal-dwarf galaxies (TDGs) have likely been produced. Here we show that such TDGs appear, after a Hubble-time of dynamical evolution in the host dark-matter halo, as objects that resemble known dSph satellite galaxies. We discuss the possibility that some of the Milky Way's satellites may be of tidal origin.

  8. Satellite Range Scheduling: A Comparison of Genetic, Heuristic and Local Search

    Computer Technologies and Information Sciences Websites

    Whitley, Darrell

    on the satellite range scheduling problem, using data from the U.S. Air Force Satellite Control Network; a simple Problem Description The U.S. Air Force Satellite Control Network (AFSCN) is responsible for coor- dinating as either low or high-altitude, corresponding to the orbit of the target satellite. The durations of low

  9. SaVi satellite constellation visualization CCSR Research Symposium 2011 Lloyd Wood, Research Fellow

    Engineering Websites

    Wood, Lloyd

    SaVi satellite constellation visualization CCSR Research Symposium 2011 ­ Lloyd Wood, Research and coverage that results from multiple satellites orbiting to form a particular satellite constellation useful simulations of satellites and constellations for research and teaching purposes. System Model: Sa

  10. Performance Analysis of LEO Satellite Networks A. Halim Zaim, Harry G. Perros, and George N. Rouskas

    Computer Technologies and Information Sciences Websites

    network that carries voice calls. Both satellite-fixed and earth-fixed constellations with inter in trajectories relative to the earth. Such a set of satellites is referred to as a constellation of satellites. Depending on the antenna technology used, satellite constellations can provide one of two types of coverage

  11. Multispectral inverse problems in satellite image processing S. A. Starks and V. Kreinovich

    Computer Technologies and Information Sciences Websites

    Kreinovich, Vladik

    Multi­spectral inverse problems in satellite image processing S. A. Starks and V. Kreinovich NASA, TX 79968, USA ABSTRACT Satellite imaging is nowadays one of the main sources of geophysical image. This case corresponds to a single satellite photo. Existing satellites (e.g., Landsat) take

  12. Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks

    Computer Technologies and Information Sciences Websites

    Sanyal, Sugata

    Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial@gmail.com *Corresponding Author Abstract Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system satellite and terrestrial networks. Keywords: Satellite-Terrestrial Network, Inter-system handover, TCP 1

  13. Vanessa L. Griffin Deputy Assistant Administrator for Satellite and Information Services (Acting)

    Environmental Sciences and Ecology Websites

    Vanessa L. Griffin Deputy Assistant Administrator for Satellite and Information Services (Acting satellites along with the production and analysis of science products using the data from those satellites. Ms.Griffin was responsible for all operations at the NOAA Satellite Operations Facility and at two

  14. Flow Control and Active Queue Management for Integrated Services in an Aeronautical Satellite Network

    Engineering Websites

    Baras, John S.

    Flow Control and Active Queue Management for Integrated Services in an Aeronautical Satellite}@umd.edu The IP-based broadband aeronautical satellite network will provide numerous new applications and services satellite networks is degraded dramatically. For the satellite channel, the window based flow control

  15. Performance-aware Security of Unicast Communication in Hybrid Satellite Networks

    Engineering Websites

    Baras, John S.

    Performance-aware Security of Unicast Communication in Hybrid Satellite Networks Ayan Roy for securing the end-to-end communication in hybrid satellite networks. Satellite networks use TCP and HTTP of the satellite channel. However, the proxy servers cannot function when IPSEC and SSL are used for secure unicast

  16. A SURVEY FOR OUTER SATELLITES OF MARS: LIMITS TO COMPLETENESS Scott S. Sheppard,1

    Physics Websites

    Jewitt, David C.

    A SURVEY FOR OUTER SATELLITES OF MARS: LIMITS TO COMPLETENESS Scott S. Sheppard,1 David Jewitt July 15 ABSTRACT We have surveyed the Hill sphere of Mars for irregular satellites. Our search covered the satellites Phobos and Deimos reside. No new satellites were found to an apparent limiting red magnitude of 23

  17. Webcam2Satellite: Estimating Cloud Maps from Webcam Imagery Calvin Murdock

    Computer Technologies and Information Sciences Websites

    Pless, Robert

    Webcam2Satellite: Estimating Cloud Maps from Webcam Imagery Calvin Murdock Washington Univ. in St historical, geo- referenced satellite imagery to learn a mapping between the satellite image and the ground a complete map. Proof of concept results show that this gives plausible estimates of satellite imagery. 1

  18. AIAA 2001-4030 CONSTRAINED TRAJECTORY GENERATION FOR MICRO-SATELLITE

    Energy Storage, Conversion and Utilization Websites

    AIAA 2001-4030 CONSTRAINED TRAJECTORY GENERATION FOR MICRO-SATELLITE FORMATION FLYING Mark B. Milam-keeping and reorientation control of a cluster of fully-actuated low-thrust micro-satellites is considered in this paper. We of the micro-satellite, it is possible to compute the control on-board the micro-satellites. Performance

  19. Hybrid satellite/terrestrial networks: State of the art and future perspectives

    Computer Technologies and Information Sciences Websites

    Papapetrou, Evaggelos

    Hybrid satellite/terrestrial networks: State of the art and future perspectives Nicolas Courville role of satellite systems in hybrid satellite/terrestrial networks will be highlighted, as well of communications and navigation of DLR and in the framework of the Satellite Communications Network of Excellence

  20. CoUrSEWork programS Master of Engineering Science (Satellite Systems Engineering).

    Computer Technologies and Information Sciences Websites

    New South Wales, University of

    CoUrSEWork programS · Master of Engineering Science (Satellite Systems Engineering). yoUr fUtUrE. yoUr ChoiCE. Satellite systems engineering is a multidisciplinary area involving many facets, employment opportunities are increasing with satellite builders, operators and users of satellite data. At

  1. Chaotic dust dynamics and implications for the hemispherical color asymmetries of the Uranian satellites

    Physics Websites

    Hamilton, Douglas P.

    satellites Daniel Tamayo a, , Joseph A. Burns a,b , Douglas P. Hamilton c a Department of Astronomy, Cornell online 27 June 2013 Keywords: Celestial mechanics Uranus, Rings Uranus, Satellites Debris disks Irregular satellites a b s t r a c t Dust grains generated by the Uranian irregular satellites will undergo chaotic

  2. Wireless Sensor Network to Satellite Master thesis in Information and Communication Technology

    Computer Technologies and Information Sciences Websites

    Brest, Université de

    Wireless Sensor Network to Satellite Interface. Master thesis in Information and Communication;Abstract This is the report describing works in the research topic: Wireless Sensor Network to Satellite technologies, especially in satellite technology, i.e pico satellite (Cube- Sat), there are several

  3. AN ULTRADEEP SURVEY FOR IRREGULAR SATELLITES OF URANUS: LIMITS TO COMPLETENESS1,2

    Physics Websites

    Jewitt, David C.

    AN ULTRADEEP SURVEY FOR IRREGULAR SATELLITES OF URANUS: LIMITS TO COMPLETENESS1,2 Scott S. Sheppard for small satellites. The 8 m Subaru Telescope was used to survey about 3.5 square degrees with a 50 of their positions) all previously known outer satellites and discovered two new irregular satellites (S/2001 U2

  4. OPTIMAL DESPIN OF A TUMBLING SATELLITE WITH AN ARBITRARY THRUSTER CONFIGURATION, INERTIA MATRIX,

    Engineering Websites

    satellite and fired remotely. If the tumbling satellite has a docking ring (such as on the Hubble Space, failed docking attempts, colli- sion with space debris, etc. In general, it cannot be assumed Telescope), a chaser satellite may rigidly dock with the tumbling satellite and then apply forces or torques

  5. Planning for Agile Earth Observation Satellites Johannes Aldinger and Johannes Lohr

    Computer Technologies and Information Sciences Websites

    Nebel, Bernhard

    Planning for Agile Earth Observation Satellites Johannes Aldinger and Johannes L¨ohr Albert}@informatik.uni-freiburg.de Abstract Agile Earth observation satellites are satellites orbiting Earth with the purpose to gather information of the Earth's surface by slewing the satellite toward regions of interest. Constraints arise

  6. ROUTING IN LEO-BASED SATELLITE NETWORKS Vidyashankar V Gounder Ravi Prakash Hosame Abu-Amara

    Computer Technologies and Information Sciences Websites

    Prakash, Ravi

    strategies have been proposed for routing in a low earth orbit (LEO) satellite system. Some of them are based and Control Centers (NOCCs) required to support the satellite system. Keywords: low earth orbit satellite. INTRODUCTION Of late, low earth orbit (LEO) and medium earth orbit (MEO) based satellite networks have become

  7. On Source Rules for ABR Service on ATM Networks with Satellite Links

    Computer Technologies and Information Sciences Websites

    Jain, Raj

    the throughput over OC-3 satellite links from 45 Mbps to 140 Mbps. 1 Introduction Satellite communication systemsOn Source Rules for ABR Service on ATM Networks with Satellite Links Sonia Fahmy, Raj Jain to ensure that the ABR ser- vice will operate e ciently over satellite links. In the cases where

  8. Achieving QoS for TCP traffic in Satellite Networks with Differentiated Services Arjan Durresi1

    Computer Technologies and Information Sciences Websites

    Jain, Raj

    intersatellite links, advanced link access methods and multicast technologies. Many new satellite communication. However, satellite systems have several inherent constraints. The resources of the satellite communication1 Achieving QoS for TCP traffic in Satellite Networks with Differentiated Services Arjan Durresi1

  9. Applicability and Performance of NEMO in Satellite Abu Zafar M. Shahriar

    Computer Technologies and Information Sciences Websites

    Atiquzzaman, Mohammed

    for satellite communications [4]. Application of MIP to satellite networks has been proposed by Israel et al. [5Applicability and Performance of NEMO in Satellite Networks Abu Zafar M. Shahriar Mohammed}@ou.edu William Ivancic Satellite Networks and Architectures Branch NASA Glenn Research Center, Cleveland, OH

  10. UW Madison PhD position in satellite remote sensing of forests Position Description

    Biology and Medicine Websites

    Turner, Monica G.

    UW Madison PhD position in satellite remote sensing of forests Position Description: A 3-year PhD research assistantship to study the use of satellite remote sensing to monitor forests. Forests, and satellite remote sensing is a key tool for such monitoring. Satellite remote sensing excels in monitoring

  11. The Colours of Satellite Galaxies in Groups and Clusters

    Astrophysics (arXiv)

    Andreea S. Font; Richard G. Bower; Ian G. McCarthy; Andrew J. Benson; Carlos S. Frenk; John C. Helly; Cedric G. Lacey; Carlton M. Baugh; Shaun Cole

    2008-09-23

    Current models of galaxy formation predict satellite galaxies in groups and clusters that are redder than observed. We investigate the effect on the colours of satellite galaxies produced by the ram pressure stripping of their hot gaseous atmospheres as the satellites orbit within their parent halo. We incorporate a model of the stripping process based on detailed hydrodynamic simulations within the Durham semi-analytic model of galaxy formation. The simulations show that the environment in groups and clusters is less aggressive than previously assumed. The main uncertainty in the model is the treatment of gas expelled by supernovae. With reasonable assumptions for the stripping of this material, we find that satellite galaxies are able to retain a significant fraction of their hot gas for several Gigayears, thereby replenishing their reservoirs of cold, star forming gas and remaining blue for a relatively long period of time. A bimodal distribution of galaxy colours, similar to that observed in SDSS data, is established and the colours of the satellite galaxies are in good agreement with the data. In addition, our model naturally accounts for the observed dependence of satellite colours on environment, from small groups to high mass clusters.

  12. A Model for Dwarf Spheroidal Satellite Galaxies without Dark Matter

    Astrophysics (arXiv)

    Ralf Klessen

    1998-01-09

    Self-consistent simulations of the dynamical evolution of low-mass satellite galaxies without dark matter on different orbits interacting with an extended Galactic dark halo are described. The calculations proceed for many orbital periods until well after the satellite dissolves. In all cases the dynamical evolution converges to a remnant that contains roughly 1% of the initial satellite mass. The stable remnant results from severe tidal shaping of the initial satellite. To an observer from Earth these remnants look strikingly similar to the Galactic dwarf spheroidal satellite galaxies. Their apparent mass-to-light ratios are very large despite the fact that they contain no dark matter. These computations show that a remnant without dark matter displays larger line-of-sight velocity dispersions for more eccentric orbits, which is a result of projection onto the observational plane. Assuming they are not dark matter dominated, it follows that the Galactic dSph satellites with sigma>6km/s should have orbital eccentricities of e>0.5. Some remnants have sub-structure along the line-of-sight that may be apparent in the morphology of the horizontal branch.

  13. Interactions of Satellite Galaxies in Cosmological Dark Matter Halos

    Astrophysics (arXiv)

    Alexander Knebe; Stuart P. D. Gill; Brad K. Gibson

    2004-02-17

    We present a statistical analysis of the interactions between satellite galaxies in cosmological dark matter halos taken from fully self-consistent high-resolution simulations of galaxy clusters. We show that the number distribution of satellite encounters has a tail that extends to as many as 3-4 encounters per orbit. On average 30% of the substructure population had at least one encounter (per orbit) with another satellite galaxy. However, this result depends on the age of the dark matter host halo with a clear trend for more interactions in younger systems. We also report a correlation between the number of encounters and the distance of the satellites to the centre of the cluster: satellite galaxies closer to the centre experience more interactions. However, this can be simply explained by the radial distribution of the substructure population and merely reflects the fact that the density of satellites is higher in those regions. In order to find substructure galaxies we applied (and present) a new technique based upon the N-body code MLAPM. This new halo finder MHF (MLAPM's-Halo-Finder) acts with exactly the same accuracy as the N-body code itself and is therefore free of any bias and spurious mismatch between simulation data and halo finding precision related to numerical effects.

  14. The peculiar velocities of satellites of external disk galaxies

    Astrophysics (arXiv)

    M. Azzaro; A. R. Zentner; F. Prada; A. Klypin

    2005-06-22

    We analyze the angular distribution and the orbital rotation directions of a sample of carefully-selected satellite galaxies extracted from the Sloan Digital Sky Survey (SDSS). We also study these statistics in an N-body simulation of cosmological structure formation set within the LCDM paradigm under various assumptions for the orientations of disk angular momenta. Assuming that the angular momenta of the disks are aligned with the angular momenta of the inner regions of their host dark matter halos, we find that the fraction of simulated satellite halos that exhibit prograde motion is 0.55-0.60, with larger satellites more likely to be prograde. In our observational sample, approximately 60% of the satellites exhibit prograde motion, a result that is broadly consistent with the simulated sample. Contrary to several recent studies, our observational sample of satellite galaxies show no evidence for being anisotropically distributed about their primary disks. Again, this result is broadly consistent with our simulated sample of satellites under the assumption that disk and halo angular momenta are aligned. However, the small size of our observational sample does not yet allow us to distinguish between various assumptions regarding the orientations of disks in their halos. Finally, we assessed the importance of contamination by interlopers on the measured prograde and retrograde statistics.

  15. Spiral and Bar Instabilities Provoked by Dark Matter Satellites

    Astrophysics (arXiv)

    John Dubinski; Jean-Rene Gauthier; Larry Widrow; Sarah Nickerson

    2008-02-27

    We explore the secular dynamical evolution of an N-body model of M31 in the presence of a population of 100 dark matter satellites over 10 Gyr. The satellite population has structural and kinematic characteristics modelled to follow the predictions of Lambda-CDM cosmological simulations. Vertical disk heating is a small effect despite many interactions with the satellite population with only a 20% increase in vertical velocity dispersion sigma_z and the disk scale height z_d at the equivalent solar radius R = 2.5R_d . However, the stellar disk is noticeably flared after 10 Gyr with z_d nearly doubling at the disk edge. Azimuthal disk heating is much larger with sigma_R and sigma_z both increasing by 1.7x. However, in a control experiment without satellites dispersion increases by 1.5x suggesting that most of the effect is due to heating through scattering off of spiral structure excited by swing-amplified noise. Surprisingly, direct impacts of satellites on the disk can excite spiral structure with a significant amplitude and in some cases impacts close to the disk center also induce the bar instability. The large number of dark matter satellite impacts expected over a galaxy's lifetime may be a significant source of external perturbations for driving disk secular evolution.

  16. Influence of relativistic effects on satellite-based clock synchronization

    Quantum Physics (arXiv)

    Jieci Wang; Zehua Tian; Jiliang Jing; Heng Fan

    2015-10-23

    Clock synchronization between ground and satellites is a fundamental issue in future quantum telecommunication, navigation and global positioning systems. Here we propose a scheme of near-earth orbit satellite-based quantum clock synchronization with atmospheric dispersion cancellation and by taking into account spacetime background of the Earth. Two frequency entangled pulses are employed to synchronize two clocks, one at a ground station and the other at a satellite. The time discrepancy of the two clocks is introduced into the pulses by moving mirrors and is extracted by measuring the coincidence rate of the pulses in the interferometer. We find that the pulses are distorted due to effects of gravity when they propagate between the Earth and the satellite, resulting in coincidence rate are remarkably affected. We also find that the precision of the clock synchronization are sensitive to the source parameters and the altitude of the satellite. The scheme provides a solution for satellite-based quantum clock synchronization with high precision, which can be in principle realized with current technology.

  17. The Abundance and Radial Distribution of Satellite Galaxies

    Astrophysics (arXiv)

    Frank C. van den Bosch; Xiaohu Yang; H. J. Mo; Peder Norberg

    2004-06-09

    Using detailed mock galaxy redshift surveys (MGRSs) we investigate the abundance and radial distribution of satellite galaxies. The mock surveys are constructed using the conditional luminosity function (CLF), and are compared against data from the 2dFGRS. We use Monte Carlo Markov Chains to explore the full posterior distribution of the CLF parameter space, and show that the average relation between light and mass is tightly constrained. The radial number density distribution of satellite galaxies in the 2dFGRS reveals a pronounced absence of satellites at small projected separations from their host galaxies. This is (at least partially) due to the overlap and merging of galaxy images in the APM catalogue. Because of the resulting close-pair incompleteness we are unfortunately unable to put meaningful constraints on the radial distribution of satellite galaxies. Marginalizing over the full CLF parameter space, we show that in a LCDM concordance cosmology the observed abundances of host and satellite galaxies in the 2dFGRS indicate a power spectrum normalization of sigma_8=0.7. The same cosmology but with sigma_8=0.9 is unable to simultanously match the abundances of host and satellite galaxies. This confirms our previous conclusions based on the pairwise peculiar velocity dispersions and the group multipliticy function.

  18. Satellite Infall and the Growth of Bulges of Spiral Galaxies

    CERN Preprints

    Eliche-Moral, M C; López-Aguerri, J A; Gonzalez-Garcia, A C

    2005-01-01

    For bulges of spiral galaxies, the concentration, or Sersic index, increases with bulge luminosity and bulge-to-disk ratio B/D (Andredakis, Peletier, & Balcells 1995, MNRAS, 275, 874). Does this trend trace the growth of bulges via satellite accretion? And, is satellite infall consistent with this trend? Aguerri, Balcells, & Peletier (2001, A&A, 367, 428) investigated this question with N-body simulations of the accretion of dense, spheroidal satellites. Here, we expand on that work by running N-body simulations of the accretion of satellites that have realistic densities. Satellites are modelled as disk-bulge structures with their own dark-matter halo. A realistic density scaling with the primary galaxy is ensured by using the Tully-Fisher relation. Our merger models show that most satellites disrupt before reaching the center. However, a bulge-disk decomposition of the surface density profile after the accretion shows an increase of both the B/D and the Sersic index n of the bulge. The increase ...

  19. The Discovery of Two New Satellites of Pluto

    Astrophysics (arXiv)

    H. A. Weaver; S. A. Stern; M. J. Mutchler; A. J. Steffl; M. W. Buie; W. J. Merline; J. R. Spencer; E. F. Young; L. A. Young

    2006-01-02

    Pluto's first known moon, Charon, was discovered in 1978 (Christy 1978) and has a diameter about half that of Pluto (Buie 1992,Young 1994, Sicardy 2005), which makes it larger relative to its primary than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful (Stern 1991, Stern 1994, Stern 2003), but they were not sensitive to objects <=150 km in diameter and there are no fundamental reasons why Pluto should not have more satellites (Stern 1994). Here we report the discovery of two additional moons around Pluto, provisionally designated S/2005 P1 (hereafter P1) and S/2005 P2 (hereafter P2), which makes Pluto the first Kuiper belt object (KBO) known to have multiple satellites. These new satellites are much smaller than Charon (diameter~1200 km), with P1 ranging in diameter from 60-165 km depending on the surface reflectivity, and P2 about 20% smaller than P1. Although definitive orbits cannot be derived, both new satellites appear to be moving in circular orbits in the same orbital plane as Charon, with orbital periods of ~38 days (P1) and ~25 days (P2). The implications of the discovery of P1 and P2 for the origin and evolution of the Pluto system, and for the satellite formation process in the Kuiper belt, are discussed in a companion paper (Stern 2006).

  20. Planes of satellite galaxies and the cosmic web

    CERN Preprints

    Libeskind, Noam I; Tully, R Brent; Courtois, Helene M; Pomarede, Daniel; Gottloeber, Stefan; Steinmetz, Matthias

    2015-01-01

    Recent observational studies have demonstrated that most satellite galaxies tend to orbit their hosts on highly flattened, vast, possibly co-rotating planes. Two nearly parallel planes of satellites have been confirmed around the M31 galaxy and around the Centaurus A galaxy, while the Milky Way also sports a plane of satellites. It has been argued that such an alignment of satellites on vast planes is unexpected in the standard ($\\Lambda$CDM) model of cosmology if not even in contradiction to its generic predictions. Guided by $\\Lambda$CDM numerical simulations, which suggest that satellites are channeled towards hosts along the axis of the slowest collapse as dictated by the ambient velocity shear tensor, we re-examine the planes of local satellites systems within the framework of the local shear tensor derived from the Cosmicflows-2 dataset. The analysis reveals that the Local Group and Centaurus A reside in a filament stretched by the Virgo cluster and compressed by the expansion of the Local Void. Four ou...

  1. A Dichotomy in Satellite Quenching Around L* Galaxies

    CERN Preprints

    Phillips, John I; Boylan-Kolchin, Michael; Bullock, James S; Cooper, Michael C; Tollerud, Erik J

    2013-01-01

    We examine the star formation properties of bright (~0.1 L*) satellites around isolated ~L* hosts in the local Universe using spectroscopically confirmed systems in the Sloan Digital Sky Survey DR7. Our selection method is carefully designed with the aid of N-body simulations to avoid groups and clusters. We find that satellites are significantly more likely to be quenched than a stellar mass-matched sample of isolated galaxies. Remarkably, this quenching occurs only for satellites of hosts that are themselves quenched: while star formation is unaffected in the satellites of star-forming hosts, satellites around quiescent hosts are more than twice as likely to be quenched than stellar-mass matched field samples. One implication of this is that whatever shuts down star formation in isolated, passive L* galaxies also plays at least an indirect role in quenching star formation in their bright satellites. The previously-reported tendency for "galactic conformity" in color/morphology may be a by-product of this ho...

  2. Heating of Galactic Disks by Infalling Satellites

    Astrophysics (arXiv)

    A. J. Benson; C. G. Lacey; C. S. Frenk; C. G. Baugh; S. Cole

    2004-03-18

    We develop an analytic model to calculate the rate at which galaxy disks are heated by dark matter substructures orbiting in their halos. The model takes into account the internal structure, mass function and accretion rate of satellites expected in the LambdaCDM cosmology, as well as the growth of the disk by accretion and mergers, but it ignores resonant heating of the disk and the dynamical effects of spiral arms and bars. We calibrate this model against N-body simulations and demonstrate that it is able to reproduce the N-body heating rates to within a factor of 3 in the majority of cases. Our model gives the distribution of disk scale-heights for galaxies of different luminosities. For L* spiral galaxies, it predicts a median disk thickness of only 5% of the radial scale-length if substructure is the only source of heating. The median disk thickness increases to nearly 20% of the radial scale-length when heating due to gravitational scattering of stars by molecular clouds is also included. The latter value is close to the thickness estimated observationally for the disk of the Milky Way galaxy. The distribution of disk thickness predicted by the model is also consistent with a recent observational determination for sub-L* galaxies by Bizyaev & Mitronova. Thus, the observed thickness of the stellar disks of spiral galaxies seems to be entirely compatible with the abundance of substructure in dark matter halos predicted by the standard Lambda-dominated cold dark matter model of structure formation. In an Omega_0=1 universe, our best model of galaxy formation produces similar scale-heights, a consequence of the fact that similar amounts of substructure are accreted by halos during the lifetime of the disk in Omega_0=1 and Omega_0=0.3, Lambda_0=0.7 cold dark matter cosmologies.

  3. 3DSig 2008: Structural Bioinformatics and Computational Biophysics Satellite Meeting, July 18-19, 2008, Toronto, Canada 3DSig 2008: Structural Bioinformatics and Computational Biophysics Satellite

    Biotechnology Websites

    Najmanovich, Rafael

    3DSig 2008: Structural Bioinformatics and Computational Biophysics Satellite Meeting, July 18-19, 2008, Toronto, Canada 1 3DSig 2008: Structural Bioinformatics and Computational Biophysics Satellite Bioinformatics and Computational Biophysics Satellite Meeting, July 18-19, 2008, Toronto, Canada 2 Table

  4. The colors of satellite galaxies in the Illustris Simulation

    CERN Preprints

    Sales, Laura V; Genel, Shy; Torrey, Paul; Nelson, Dylan; Rodriguez-Gomez, Vicente; Wang, Wenting; Pillepich, Annalisa; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2014-01-01

    Observationally, the fraction of blue satellite galaxies decreases steeply with host halo mass, and their radial distribution around central galaxies is significantly shallower in massive (M_* >10e11M_sun) than in Milky Way like systems. Theoretical models, based primarily on semi-analytical techniques, have had a long-standing problem with reproducing these trends, instead predicting too few blue satellites in general but also estimating a radial distribution that is too shallow, regardless of primary mass. In this Letter, we use the Illustris cosmological simulation to study the properties of satellite galaxies around isolated primaries. For the first time, we find good agreement between theory and observations. We identify the main source of this success relative to earlier work to be a consequence of the large gas contents of satellites at infall, a factor ~5-10 times larger than in semi-analytical models. Because of their relatively large gas reservoirs, satellites can continue to form stars long after i...

  5. Satellite Galaxies and Fossil Groups in the Millennium Simulation

    Astrophysics (arXiv)

    L. V. Sales; J. F. Navarro; D. G. Lambas; S. D. M. White; D. J. Croton

    2007-09-27

    We use a semianalytic galaxy catalogue constructed from the Millennium Simulation to study the satellites of isolated galaxies in the LCDM cosmogony. This sample (~80,000$ bright primaries, surrounded by ~178,000 satellites) allows the characterization, with minimal statistical uncertainty, of the dynamical properties of satellite/primary galaxy systems in a LCDM universe. We find that, overall, the satellite population traces the dark matter rather well: its spatial distribution and kinematics may be approximated by an NFW profile with a mildly anisotropic velocity distribution. Their spatial distribution is also mildly anisotropic, with a well-defined ``anti-Holmberg'' effect that reflects the misalignment between the major axis and angular momentum of the host halo. The isolation criteria for our primaries picks not only galaxies in sparse environments, but also a number of primaries at the centre of ''fossil'' groups. We find that the abundance and luminosity function of these unusual systems are in reasonable agreement with the few available observational constraints. We recover the expected L_{host} \\sigma_{sat}^3 relation for LCDM models for truly-isolated primaries. Less strict primary selection, however, leads to substantial modification of the scaling relation. Our analysis also highlights a number of difficulties afflicting studies that rely on blind stacking of satellite systems to constrain the mean halo mass of the primary galaxies.

  6. The Luminosity Function of the Milky Way Satellites

    Astrophysics (arXiv)

    S. Koposov; V. Belokurov; N. W. Evans; P. C. Hewett; M. J. Irwin; G. Gilmore; D. B. Zucker; H. -W. Rix; M. Fellhauer; E. F. Bell; E. V. Glushkova

    2008-05-19

    We quantify the detectability of stellar Milky Way satellites in the Sloan Digital Sky Survey (SDSS) Data Release 5. We show that the effective search volumes for the recently discovered SDSS--satellites depend strongly on their luminosity, with their maximum distance, $D_{max}$, substantially smaller than the Milky Way halo's virial radius. Calculating the maximum accessible volume, $V_{max}$, for all faint detected satellites, allows the calculation of the luminosity function for Milky Way satellite galaxies, accounting quantitatively for their detectability. We find that the number density of satellite galaxies continues to rise towards low luminosities, but may flatten at $M_V \\sim -5$; within the uncertainties, the luminosity function can be described by a single power law $dN/dM_{V}= 10 \\times 10^{0.1 (M_V+5)}$, spanning luminosities from $M_V=-2$ all the way to the luminosity of the Large Magellanic Cloud. Comparing these results to several semi-analytic galaxy formation models, we find that their predictions differ significantly from the data: either the shape of the luminosity function, or the surface brightness distributions of the models, do not match.

  7. Disruption of Dwarf Satellite Galaxies without Dark Matter

    CERN Preprints

    Casas, Rigoberto A

    2011-01-01

    The evolution of a satellite galaxy of a Milky Way like galaxy has been studied using N-Body simulations. The initial satellites, containing one million particles, have been simulated by a Plummer sphere, while the potential of the host galaxy is a three component rigid potential: disc, bulge and dark matter halo. It has been found that several orbits of the satellites allow for the existence, for about 1 Gyr or more, of an out-of-equilibrium body that could be interpreted as a dSph satellite galaxy of the Milky Way. In addition, from the study of the evolution of the mass-to-light ratios of satellites that show a disrupted phase it has been found that it is possible that some dSph galaxies of the Milky Way with large M/L ratios might not be dark matter dominated and that their high mass to light ratios are observed because they are out of equilibrium objects.

  8. Spectroscopic confirmation of hydrogen alpha-selected satellite galaxies

    CERN Preprints

    Ivory, Clare F

    2010-01-01

    We present a spectroscopic test confirming the potential of narrow-band optical imaging as a method for detecting star-forming satellites around nearby galaxies. To date the efficiency of such methods, and particularly the fraction of false detections resulting from its use, has not been tested. In this paper we use optical spectroscopy to verify the nature of objects that are apparently emission-line satellites, taken from imaging presented elsewhere. Observations of 12 probable satellites around 11 host galaxies are presented and used to compare the recession velocities of the host and satellite. This test confirms, in all cases, that there is genuine line emission, that the detected line is hydrogen alpha, and that the satellites have similar recession velocities to their hosts with a maximum difference of ~ 250 km/s, consistent with their being gravitationally bound companions. We conclude that the spectroscopy has confirmed that narrow-band imaging through H alpha filters is a reliable method for detecti...

  9. Dark-matter decays and Milky Way satellite galaxies

    HEP - Phenomenology (arXiv)

    Annika H. G. Peter; Andrew J. Benson

    2010-09-09

    We consider constraints on a phenomenological dark-matter model consisting of two nearly degenerate particle species using observed properties of the Milky Way satellite galaxy population. The two parameters of this model, assuming the particle masses are >~ GeV, are v_k, the recoil speed of the daughter particle, and tau, the lifetime of the parent particle. The satellite constraint that spans the widest range of v_k is the number of satellites that have a mass within 300 pc M300 > 5 x 10^6 solar masses, although constraints based on M300 in the classical dwarfs and the overall velocity function are competitive for v_k >~ 50 km/s. In general, we find that tau <~ 30 Gyr is ruled out for 20 km/s <~ v_k <~ 200 km/s, although we find that the limits on tau for fixed v_k can change constraints by a factor of ~3 depending on the star-formation histories of the satellites. We advocate using the distribution of M300 in Milky Way satellites determined by next-generation all-sky surveys and follow-up spectroscopy as a probe of dark-matter properties.

  10. The Discovery of Two New Satellites of Pluto

    CERN Preprints

    Weaver, H A; Mutchler, M J; Steffl, A J; Buie, M W; Merline, W J; Spencer, J R; Young, E F; Young, L A

    2006-01-01

    Pluto's first known moon, Charon, was discovered in 1978 (Christy 1978) and has a diameter about half that of Pluto (Buie 1992,Young 1994, Sicardy 2005), which makes it larger relative to its primary than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful (Stern 1991, Stern 1994, Stern 2003), but they were not sensitive to objects <=150 km in diameter and there are no fundamental reasons why Pluto should not have more satellites (Stern 1994). Here we report the discovery of two additional moons around Pluto, provisionally designated S/2005 P1 (hereafter P1) and S/2005 P2 (hereafter P2), which makes Pluto the first Kuiper belt object (KBO) known to have multiple satellites. These new satellites are much smaller than Charon (diameter~1200 km), with P1 ranging in diameter from 60-165 km depending on the surface reflectivity, and P2 about 20% smaller than P1. Although definitive orbits cannot be derived, both new satellites appear to be moving in circ...

  11. Experimental Single-Photon Transmission from Satellite to Earth

    Quantum Physics (arXiv)

    Juan Yin; Yuan Cao; Shu-Bin Liu; Ge-Sheng Pan; Jin-Hong Wang; Tao Yang; Zhong-Ping Zhang; Fu-Min Yang; Yu-Ao Chen; Cheng-Zhi Peng; Jian-Wei Pan

    2013-06-04

    Free-space quantum communication with satellites opens a promising avenue for global secure quantum network and large-scale test of quantum foundations. Recently, numerous experimental efforts have been carried out towards this ambitious goal. However, one essential step - transmitting single photons from the satellite to the ground with high signal-to-noise ratio (SNR) at realistic environments - remains experimental challenging. Here, we report a direct experimental demonstration of the satellite-ground transmission of a quasi-single-photon source. In the experiment, single photons (~0.85 photon per pulse) are generated by reflecting weak laser pulses back to earth with a cube-corner retro-reflector on the satellite Champ, collected by a 600-mm diameter telescope at the ground station, and finally detected by single-photon counting modules (SPCMs) after 400-km free-space link transmission. With the help of high accuracy time synchronization, narrow receiver field-of-view (FOV) and high-repetition-rate pulses (76 MHz), a SNR of better than 16:1 is obtained, which is sufficient for a secure quantum key distribution. Our experimental results represent an important step towards satellite-ground quantum communication.

  12. Disentangling satellite galaxy populations using orbit tracking in simulations

    CERN Preprints

    Oman, Kyle A; Behroozi, Peter S

    2013-01-01

    Physical processes regulating star formation in satellite galaxies represent an area of ongoing research, but the projected nature of observed coordinates makes separating different populations of satellites (with different processes at work) difficult. The orbital history of a satellite galaxy leads to its present-day phase space coordinates; we can also work backwards and use these coordinates to statistically infer information about the orbital history. We use merger trees from the MultiDark Run 1 N-body simulation to compile a catalog of the orbits of satellite haloes in cluster environments. We parameterize the orbital history by the time since crossing within 2.5 rvir of the cluster centre and use our catalog to estimate the probability density over a range of this parameter given a set of present-day projected (i.e. observable) phase space coordinates. We show that different populations of satellite haloes, e.g. infalling, backsplash and virialized, occupy distinct regions of phase space, and semi-dist...

  13. Stability of Satellites Around Close-in Extrasolar Giant Planets

    Astrophysics (arXiv)

    Jason W. Barnes; D. P. O'Brien

    2002-05-02

    We investigate the long-term dynamical stability of hypothetical moons orbiting extrasolar giant planets. Stellar tides brake a planet's rotation and, together with tidal migration, act to remove satellites; this process limits the lifetimes of larger moons in extrasolar planetary systems. Because more massive satellites are removed more quickly than less massive ones, we are able to derive an upper mass limit for those satellites that might have survived to the present day. For example, we estimate that no primordial satellites with masses greater than 7 x 10^{-7} M_Earth$ (~ \\70km radius for rho=3 g cm^{-3}) could have survived around the transiting planet HD209458b for the age of the system. No meaningful mass limits can be placed on moons orbiting Jovian planets more than ~0.6 AU from their parent stars. Earth-like moons of Jovian planets could exist for 5 Gyr in systems where the stellar mass is greater than 0.15 M_Sun. Transits show the most promise for the discovery of extrasolar moons -- we discuss prospects for satellite detection via transits using space-based photometric surveys and the limits on the planetary tidal dissipation factor Q that a discovery would imply.

  14. Tidal disruption of satellites and formation of narrow rings

    CERN Preprints

    Leinhardt, Zoe M; Latter, Henrik N; Kokubo, Eiichiro

    2012-01-01

    In this paper we investigate the formation of narrow planetary rings such as those found around Uranus and Saturn through the tidal disruption of a weak, gravitationally bound satellite that migrates within its Roche limit. Using $N$-body simulations, we study the behaviour of rubble piles placed on circular orbits at different distances from a central planet. We consider both homogeneous satellites and differentiated bodies containing a denser core. We show that the Roche limit for a rubble pile is closer to the planet than for a fluid body of the same mean density. The Roche limit for a differentiated body is also closer to the planet than for a homogeneous satellite of the same mean density. Within its Roche limit, a homogeneous satellite totally disrupts and forms a narrow ring. The initial stages of the disruption are similar to the evolution of a viscous fluid ellipsoid, which can be computed semi-analytically. On the other hand, when a differentiated satellite is just within the Roche limit only the ma...

  15. NatioNal ENviroNmENtal SatEllitE Data & iNformatioN SErvicE

    Environmental Sciences and Ecology Websites

    NatioNal ENviroNmENtal SatEllitE Data & iNformatioN SErvicE JoiNt Polar SatEllitE SyStEm The restructured Joint Polar Satellite System (formerly -- National Polar-orbiting Environmental Satellite System's civil and military polar-orbiting meteorological satellite systems into a single, national system

  16. Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints

    CERN Preprints

    Lei, Jiang; Vázquez-Castro, M A; Hjørungnes, Are

    2011-01-01

    In this paper, we study multibeam satellite secure communication through physical (PHY) layer security techniques, i.e., joint power control and beamforming. By first assuming that the Channel State Information (CSI) is available and the beamforming weights are fixed, a novel secure satellite system design is investigated to minimize the transmit power with individual secrecy rate constraints. An iterative algorithm is proposed to obtain an optimized power allocation strategy. Moreover, sub-optimal beamforming weights are obtained by completely eliminating the co-channel interference and nulling the eavesdroppers' signal simultaneously. In order to obtain jointly optimized power allocation and beamforming strategy in some practical cases, e.g., with certain estimation errors of the CSI, we further evaluate the impact of the eavesdropper's CSI on the secure multibeam satellite system design. The convergence of the iterative algorithm is proven under justifiable assumptions. The performance is evaluated by taki...

  17. Orbital Perturbations of the Galilean Satellites During Planetary Encounters

    CERN Preprints

    Deienno, R; Vokrouhlicky, D; Yokoyama, T

    2014-01-01

    The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present Solar System, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites, and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorny & Morbidelli (2012) that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly af...

  18. Satellite Orbits and Relative Motion in Levi-Civita Coordinates

    CERN Preprints

    Humi, Mayer

    2015-01-01

    In this paper we consider satellite trajectories in central force field with quadratic drag using two formalisms. The first using polar coordinates in which the angular momentum plays a dominant role. The second is in Levi-Civita coordinates in which the energy plays a central role. We then unify these two formalisms by introducing polar coordinates in Levi-Civita space and derive a new equation for satellite orbits in which energy and and angular momentum are on equal footing {and thus characterize the orbit by its two invariants}. In the second part of the paper we derive in Levi-Civita coordinates a linearized equation for the relative motion of two satellites whose trajectories are in the same plane. We carry out also a numerical verification of these equations.

  19. NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn

    CERN Preprints

    Grav, Tommy; Mainzer, Amy K; Masiero, Joe R; Nugent, Carrie R; Cutri, Roc M; Sonnet, Sarah; Kramer, Emily

    2015-01-01

    We present thermal model fits for 11 Jovian and 3 Saturnian irregular satellites based on measurements from the WISE/NEOWISE dataset. Our fits confirm spacecraft-measured diameters for the objects with in situ observations (Himalia and Phoebe) and provide diameters and albedo for 12 previously unmeasured objects, 10 Jovian and 2 Saturnian irregular satellites. The best-fit thermal model beaming parameters are comparable to what is observed for other small bodies in the outer Solar System, while the visible, W1, and W2 albedos trace the taxonomic classifications previously established in the literature. Reflectance properties for the irregular satellites measured are similar to the Jovian Trojan and Hilda Populations, implying common origins.

  20. Satellite Orbits and Relative Motion in Levi-Civita Coordinates

    Mathematical Physics (arXiv)

    Mayer Humi

    2015-07-26

    In this paper we consider satellite trajectories in central force field with quadratic drag using two formalisms. The first using polar coordinates in which the angular momentum plays a dominant role. The second is in Levi-Civita coordinates in which the energy plays a central role. We then unify these two formalisms by introducing polar coordinates in Levi-Civita space and derive a new equation for satellite orbits in which energy and and angular momentum are on equal footing {and thus characterize the orbit by its two invariants}. In the second part of the paper we derive in Levi-Civita coordinates a linearized equation for the relative motion of two satellites whose trajectories are in the same plane. We carry out also a numerical verification of these equations.

  1. A Curious New Milky Way Satellite in Ursa Major

    CERN Preprints

    Zucker, D B; Evans, N W; Irwin, M J; Kleyna, J T; Wilkinson, M I; Fellhauer, M; Bramich, D M; Gilmore, G; Newberg, H J; Yanny, B; Smith, J A; Hewett, P C; Bell, E F; Rix, H W; Gnedin, O Y; Vidrih, S; Wyse, R F G; Willman, B; Grebel, E K; Schneider, D P; Beers, T C; Kniazev, A Yu; Barentine, J C; Brewington, H; Brinkmann, J; Harvanek, M; Kleinman, S J; Krzesínski, J; Long, D; Nitta, A; Snedden, S A

    2006-01-01

    In this Letter, we study a localized stellar overdensity in the constellation of Ursa Major, first identified in the Sloan Digital Sky Survey (SDSS) data and subsequently followed up with Subaru imaging. Its color-magnitude diagram shows a well-defined sub-giant branch, main sequence and turn-off, from which we estimate a distance of about 30 kpc and a projected size of about 250 pc. Based on its extent and its stellar population, we argue that this is a previously unknown satellite galaxy of the Milky Way, hereby named after its constellation as Ursa Major II (UMa II). Using SDSS data, we find an absolute magnitude of M_V = -3.8, which would make it the faintest known satellite galaxy. UMa II's isophotes are irregular and distorted with evidence for multiple concentrations; this suggests that the satellite may be in the process of disruption.

  2. A Curious New Milky Way Satellite in Ursa Major

    Astrophysics (arXiv)

    D. B. Zucker; V. Belokurov; N. W. Evans; J. T. Kleyna; M. J. Irwin; M. I. Wilkinson; M. Fellhauer; D. M. Bramich; G. Gilmore; H. J. Newberg; B. Yanny; J. A. Smith; P. C. Hewett; E. F. Bell; H. -W. Rix; O. Y. Gnedin; S. Vidrih; R. F. G. Wyse; B. Willman; E. K. Grebel; D. P. Schneider; T. C. Beers; A. Y. Kniazev; J. C. Barentine; H. Brewington; J. Brinkmann; M. Harvanek; S. J. Kleinman; J. Krzesinski; D. Long; A. Nitta; S. A. Snedden

    2006-07-04

    In this Letter, we study a localized stellar overdensity in the constellation of Ursa Major, first identified in Sloan Digital Sky Survey (SDSS) data and subsequently followed up with Subaru imaging. Its color-magnitude diagram (CMD) shows a well-defined sub-giant branch, main sequence and turn-off, from which we estimate a distance of ~30 kpc and a projected size of ~250 x 125 pc. The CMD suggests a composite population with some range in metallicity and/or age. Based on its extent and stellar population, we argue that this is a previously unknown satellite galaxy of the Milky Way, hereby named Ursa Major II (UMa II) after its constellation. Using SDSS data, we find an absolute magnitude of M_V \\~ -3.8, which would make it the faintest known satellite galaxy. UMa II's isophotes are irregular and distorted with evidence for multiple concentrations; this suggests that the satellite is in the process of disruption.

  3. Channel Estimation And Multiuser Detection In Asynchronous Satellite Communications

    CERN Preprints

    Chaouech, Helmi; 10.5121/ijwmn.2010.2411

    2010-01-01

    In this paper, we propose a new method of channel estimation for asynchronous additive white Gaussian noise channels in satellite communications. This method is based on signals correlation and multiuser interference cancellation which adopts a successive structure. Propagation delays and signals amplitudes are jointly estimated in order to be used for data detection at the receiver. As, a multiuser detector, a single stage successive interference cancellation (SIC) architecture is analyzed and integrated to the channel estimation technique and the whole system is evaluated. The satellite access method adopted is the direct sequence code division multiple access (DS CDMA) one. To evaluate the channel estimation and the detection technique, we have simulated a satellite uplink with an asynchronous multiuser access.

  4. Modeling the Jovian subnebula: II - Composition of regular satellites ices

    Astrophysics (arXiv)

    Olivier Mousis; Yann Alibert

    2005-10-28

    We use the evolutionary turbulent model of Jupiter's subnebula described by Alibert et al. (2005a) to constrain the composition of ices incorporated in its regular icy satellites. We consider CO2, CO, CH4, N2, NH3, H2S, Ar, Kr, and Xe as the major volatile species existing in the gas-phase of the solar nebula. All these volatile species, except CO2 which crystallized as a pure condensate, are assumed to be trapped by H2O to form hydrates or clathrate hydrates in the solar nebula. Once condensed, these ices were incorporated into the growing planetesimals produced in the feeding zone of proto-Jupiter. Some of these solids then flowed from the solar nebula to the subnebula, and may have been accreted by the forming Jovian regular satellites. We show that ices embedded in solids entering at early epochs into the Jovian subdisk were all vaporized. This leads us to consider two different scenarios of regular icy satellites formation in order to estimate the composition of the ices they contain. In the first scenario, icy satellites were accreted from planetesimals that have been produced in Jupiter's feeding zone without further vaporization, whereas, in the second scenario, icy satellites were accreted from planetesimals produced in the Jovian subnebula. In this latter case, we study the evolution of carbon and nitrogen gas-phase chemistries in the Jovian subnebula and we show that the conversions of N2 to NH3, of CO to CO2, and of CO to CH4 were all inhibited in the major part of the subdisk. Finally, we assess the mass abundances of the major volatile species with respect to H2O in the interiors of the Jovian regular icy satellites. Our results are then compatible with the detection of CO2 on the surfaces of Callisto and Ganymede and with the presence of NH3 envisaged in subsurface oceans within Ganymede and Callisto.

  5. Sinking Satellites and the Heating of Galaxy Discs

    Astrophysics (arXiv)

    H. Velazquez; Simon D. M. White

    1998-09-30

    We have carried out a set of self-consistent N-body simulations to study the interaction between disc galaxies and merging satellites with the aim of determining the disc kinematical changes induced by such events. We explore a region of the parameter space embracing satellites with different masses and internal structure and orbits of various eccentricities. We find that the analyt ic estimates of T\\'oth and Ostriker (1992) are high; overestimating the disc heating and thickening resulting from the accretion process by a factor of about 2-3. We find that the heating and thickening of the disc differ for satellites on prograde and retrograde orbits. The former tend to heat the stellar disc while the latter primarily produce a coherent tilt. Thus, disc galaxies may accrete quite massive satellites without destroying the disc, particularly, if the orbits are retrograde. We also find that a massive bulge may play a role in reducing these effects. We have quantified the importance of the responsiveness of the halo by replacing it by a rigid potentia l in several simulations. In these cases, the increase of the vertical scale length is larger by a factor of $1.5-2$, indicating that a self-consistent treatment is essential to get realistic results. A frequent by-product of the accretion process is the formation of weak stellar warps and asymmetric discs. Finally, we have checked how well Chandrasekhar's dynamical friction formula reproduces the sinking rates in several of our experiments. We find that it works well provided a suitable value is chosen for the Coulomb logarithm and the satellite mass is taken to be the mass still bound to the satellite at each moment.

  6. Recent Improvements in Testing General Relativity with Satellite Laser Ranging

    General Relativity & Quantum Cosmology (arXiv)

    Lorenzo Iorio

    2002-05-22

    In this work some aspects of the detection of certain general relativistic effects in the weak gravitational field of the Earth via laser-ranged data to some existing or proposed geodetic satellites are examined. The focus is on the Lense-Thirring drag of the orbit of a test body, the gravitomagnetic clock effect and the gravitoelectric perigee shift. The impact of some sources of systematic errors is investigated. An experiment whose goal is the measurement of the PPN parameters beta and gamma in the terrestrial field with LAGEOS satellites at a level of 10^(-3)is presented. A modified version of the proposed LARES mission is examined.

  7. The velocity distribution of SDSS satellites in MOND

    Astrophysics (arXiv)

    Garry Angus; Benoit Famaey; Olivier Tiret; Francoise Combes; HongSheng Zhao

    2007-09-12

    The recent SDSS measured velocity distribution of satellite galaxies has been modelled in the context of MOND. We show that even when the extra constraint of adhering to the projected satellite number density profile is added, the two line of sight (los) velocity dispersion profiles presented in Klypin & Prada (2007) can be matched simply with a radially varying anisotropy. Interestingly, the anisotropies required to fit the los velocity dispersions are remarkably similar to the anisotropies generated by dissipationless collapse simulations in MOND. The mass-to-light ratios of the two host galaxies used are sensible and positivity of the distribution function is satisfied.

  8. Measuring Time of Flight Using Satellite-Based Clocks

    Physics (arXiv)

    Ronald A. J. van Elburg

    2011-11-18

    Considering the OPERA neutrino-velocity measurement from the point of view of a GPS satellite we find that the detector at Gran Sasso has a velocity component in the order of $10^{-5}c$ towards the neutrino emission location at CERN. On GPS-receivers this translates into first-order Doppler terms, therefore a correction is required for, among other things, this ephemeris-and-location-dependent relativistic effect. To ensure correct time-of-flight measurements using satellite-based clocks we propose to extend their calibration procedures with an explicit check on these relativistic corrections.

  9. Silicon avalanche photodiode operation and lifetime analysis for small satellites

    Quantum Physics (arXiv)

    Yue Chuan Tan; Rakhitha Chandrasekara; Cliff Cheng; Alexander Ling

    2013-06-28

    Silicon avalanche photodiodes (APDs) are sensitive to operating temperature fluctuations and are also susceptible to radiation flux expected in satellite-based quantum experiments. We introduce a low power voltage adjusting mechanism to overcome the effects of in-orbit temperature fluctuations. We also present data on the performance of Si APDs after irradiation (gamma-ray and proton beam). Combined with an analysis of expected orbital irradiation, we propose that a Si APD in a 400 km equatorial orbit may operate beyond the lifetime of the satellite.

  10. Satellite Quantum Communication via the Alphasat Laser Communication Terminal

    Quantum Physics (arXiv)

    Dominique Elser; Kevin Günthner; Imran Khan; Birgit Stiller; Christoph Marquardt; Gerd Leuchs; Karen Saucke; Daniel Tröndle; Frank Heine; Stefan Seel; Peter Greulich; Herwig Zech; Björn Gütlich; Ines Richter; Rolf Meyer

    2015-10-15

    By harnessing quantum effects, we nowadays can use encryption that is in principle proven to withstand any conceivable attack. These fascinating quantum features have been implemented in metropolitan quantum networks around the world. In order to interconnect such networks over long distances, optical satellite communication is the method of choice. Standard telecommunication components allow one to efficiently implement quantum communication by measuring field quadratures (continuous variables). This opens the possibility to adapt our Laser Communication Terminals (LCTs) to quantum key distribution (QKD). First satellite measurement campaigns are currently validating our approach.

  11. Searching for Tidal Tails in Galactic Dwarf Spheroidal Satellites

    Astrophysics (arXiv)

    D. Martinez-Delgado; A. Aparicio; M. A. Gomez-Flechoso

    2000-09-05

    We present preliminary results of a long-term project to investigate the process of accretion and tidal disruption of dSph satellites in the Galactic halo and, in particular, to search for new tidal tails in a sample of nearby dSph satellites of the Milky Way. Here we present our finding of extra-tidal debris in the Ursa Minor dS ph and discuss the detection by the Sloan Digitized Sky Survey team of what could be a tidal stream associated to the Sagittarius dSph.

  12. Satellite design parameters for detecting coherence in the microwave sky

    Astrophysics (arXiv)

    Andreas Albrecht; Benjamin D. Wandelt

    1996-02-22

    Recently it has been realized that observations of fluctuations in the cosmic microwave background (CMB) can reveal very interesting information about the degree of coherence exhibited by the perturbations at early times. This fact should allow sufficiently detailed observations to clearly differentiate among several competing models of structure formation. We study the mission parameters required for a satellite to address the issue of coherence. Our results emphasize the importance of a small beamwidth, and support the cases for the PSI, FIRE and COBRAS/SAMBA satellite proposals (in increasing order of resolving power). Design parameters for a fourth proposal, MAP, have not been made available.

  13. AB Levitrons and their Applications to Earth's Motionless Satellites

    CERN Preprints

    Bolonkin, Alexander

    2007-01-01

    Author offers the new and distinctly revolutionary method of levitation in artificial magnetic field. It is shown that a very big space station and small satellites may be suspended over the Earth's surface and used as motionless radio-TV translators, telecommunication boosters, absolute geographic position locators, personal and mass entertainment and as planet-observation platforms. Presented here is the theory of big AB artificial magnetic field and levitation in it is generally developed. Computation of three macro-projects: space station at altitude 100 km, TV-communication antenna at height 500 m, and multi-path magnetic highway. Key words: levitation, AB Levitrons, motionless space satellite.

  14. Dwarf Spheroidal Satellite Galaxies and the Galactic Tidal Field

    Astrophysics (arXiv)

    Pavel Kroupa

    1996-12-03

    The Milky Way is surrounded by nine or more dwarf-spheroidal (dSph) satellite galaxies that appear to consist primarily of dark matter. Here I summarise research that shows that initially spherical bound low-mass satellites without dark matter, that are on orbits within a massive Galactic dark corona, can evolve into remnants that are non-spherical, have a non-isotropic velocity dispersion tensor and are not in virial equilibrium, but are bright enough for sufficiently long times to be mistaken for dark-matter dominated dSph galaxies.

  15. AB Levitrons and their Applications to Earth's Motionless Satellites

    Physics (arXiv)

    Alexander Bolonkin

    2007-08-18

    Author offers the new and distinctly revolutionary method of levitation in artificial magnetic field. It is shown that a very big space station and small satellites may be suspended over the Earth's surface and used as motionless radio-TV translators, telecommunication boosters, absolute geographic position locators, personal and mass entertainment and as planet-observation platforms. Presented here is the theory of big AB artificial magnetic field and levitation in it is generally developed. Computation of three macro-projects: space station at altitude 100 km, TV-communication antenna at height 500 m, and multi-path magnetic highway. Key words: levitation, AB Levitrons, motionless space satellite.

  16. Satellite Quantum Communication via the Alphasat Laser Communication Terminal

    CERN Preprints

    Elser, Dominique; Khan, Imran; Stiller, Birgit; Marquardt, Christoph; Leuchs, Gerd; Saucke, Karen; Tröndle, Daniel; Heine, Frank; Seel, Stefan; Greulich, Peter; Zech, Herwig; Gütlich, Björn; Richter, Ines; Meyer, Rolf

    2015-01-01

    By harnessing quantum effects, we nowadays can use encryption that is in principle proven to withstand any conceivable attack. These fascinating quantum features have been implemented in metropolitan quantum networks around the world. In order to interconnect such networks over long distances, optical satellite communication is the method of choice. Standard telecommunication components allow one to efficiently implement quantum communication by measuring field quadratures (continuous variables). This opens the possibility to adapt our Laser Communication Terminals (LCTs) to quantum key distribution (QKD). First satellite measurement campaigns are currently validating our approach.

  17. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part I: Improved Method and Uncertainties

    Environmental Sciences and Ecology Websites

    Kummerow, Christian

    Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part I for estimating surface rain rate, convective rain proportion, and latent heating profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches

  18. Interactions between TCP and link layer protocols on mobile satellite links

    MIT - DSpace

    Faulkner, Edward A., 1980-

    2004-01-01

    High speed satellite-based data networks are highly desirable for a variety of mobile applications. In order to inter-operate with existing networks, satellite-based systems must support TCP/IP traffic. However, TCP performs ...

  19. Space Debris Removal with an Ion Beam Shepherd Satellite: target-plasma interaction

    Plasma Physics and Fusion Websites

    Carlos III de Madrid, Universidad

    Space Debris Removal with an Ion Beam Shepherd Satellite: target-plasma interaction M. Merino , E., with permission. #12;Figure 1. Schematic of ion beam shepherd satellite deorbiting a space debris describing

  20. Improved detection of sulphur dioxide in volcanic plumes using satellite-based hyperspectral infrared measurements

    Physics Websites

    Oxford, University of

    Improved detection of sulphur dioxide in volcanic plumes using satellite-based hyperspectral dioxide (SO2) released was low. The potential of hyperspectral thermal infrared measurements satellite-based hyperspectral infrared measurements: Application to the Eyjafjallajökull 2010 eruption, J

  1. Resource allocation and scheduling for communication satellites with advanced transmission antennas

    MIT - DSpace

    Choi, Jihwan Patrick, 1975-

    2006-01-01

    For multimedia and other data services over satellite networks, the efficient management of scarce satellite communication resources is critical for the economic competitiveness of the medium. To support a broad spectrum ...

  2. Retrieving marine inherent optical properties from satellites using temperature and salinity-

    Geosciences Websites

    Boss, Emmanuel S.

    Retrieving marine inherent optical properties from satellites using temperature and salinity-series of marine inherent optical properties (IOPs) from ocean color satellite instruments provide valuable data matter absorption, and leave the derived absorption by phytoplankton unchanged. © 2013 Optical Society

  3. The co-planarity of satellite galaxies delivered by randomly aligned cold mode accretion streams

    CERN Preprints

    Goerdt, Tobias

    2013-01-01

    Recent observations have shown that the majority of the Andromeda galaxy's satellites are aligned in a thin plane. On the theoretical side it has been proposed that galaxies acquire their gas via cold streams. In addition, numerical simulations show that the same streams also deliver satellites. Assuming that cold streams are the major source of satellite systems around galaxies we calculate the probabilities to find a certain fraction of satellites within a thin plane around the central galaxy of the host halo. Using simple geometrical considerations and adopting a random orientation of the streams we demonstrate that the vast thin disk of satellites detected around Andromeda can naturally be explained within this framework. In fact, without any satellite scattering, three streams or less would lead to too many satellites in the thin plane, compared with the observations. Four to seven streams reproduce the observations very well. Thin disks of satellites might therefore provide important relic information a...

  4. Direct measurements of laser light aberration from the ARTEMIS geostationary satellite through thin clouds

    CERN Preprints

    Kuzkov, Volodymyr; Sodnik, Zoran

    2015-01-01

    A precise ground based telescope system was developed for laser communication experiments with the geostationary satellite ARTEMIS of ESA. Precise tracking of the satellite was realized by using time resolved coordinates of the satellite. During the experiments, the time propagation of laser signal from the satellite and the point-ahead angle for the laser beam were calculated. Some laser experiments though thin clouds were performed. A splitting of some images of the laser beam from the satellite along declination and right ascension coordinates of telescope could be observed through thin clouds. The splitting along the declination coordinate may be interpreted as refraction in the atmosphere. The splitting along the right ascension coordinate is equivalent to the calculated point-ahead angle for the satellite. We find out that a small part of laser beam was observed ahead of the velocity vector in the point where the satellite would be after the laser light from the satellite reaches the telescope. These re...

  5. Synchronization of system-of-systems interfaces in military satellite communications

    MIT - DSpace

    Davis, Mark J. (Mark Jeffrey)

    2008-01-01

    Military systems continue to become more complex and nearly all are now part of one or more system of systems (SoS). Military satellite communications programs have expanded over the last decade from three distinct satellite ...

  6. Thermal monitoring of Nyiragongo SATELLITE OBSERVATIONS OF THERMAL EMISSION

    Geosciences Websites

    Wright, Robert

    of significant thermal activity prior to the start of the eruption on January 17, 2002. Thermal radiance dataThermal monitoring of Nyiragongo SATELLITE OBSERVATIONS OF THERMAL EMISSION BEFORE, DURING This paper presents a two-year archive of thermal observations made before, during, and after the January

  7. Validation of satellite ozone profile retrievals using Beijing ozonesonde data

    Geosciences Websites

    Pan, Laura

    in the stratosphere and troposphere. Stratospheric ozone forms a protective layer that absorbs enough solarValidation of satellite ozone profile retrievals using Beijing ozonesonde data Jianchun Bian,1 year time period (September 2002 to July 2005) are used to evaluate the performance of ozone profile

  8. Satellite measurements of the clear-sky greenhouse effect from

    Computer Technologies and Information Sciences Websites

    LETTERS Satellite measurements of the clear-sky greenhouse effect from tropospheric ozone HELEN M of 0.48±0.14 W m-2 between 45 S and 45 N. This estimate of the clear-sky greenhouse effect from, USA Present Address: Atmospheric Chemistry Division, National Center for Atmospheric Research, PO Box

  9. Testing modified gravity with motion of satellites around galaxies

    General Relativity & Quantum Cosmology (arXiv)

    J. W. Moffat; V. T. Toth

    2008-08-10

    A modified gravity (MOG) theory, that has been successfully fitted to galaxy rotational velocity data, cluster data, the Bullet Cluster 1E0657-56 and cosmological observations, is shown to be in good agreement with the motion of satellite galaxies around host galaxies at distances 50-400 kpc.

  10. Methods for verifying satellite precipitation estimates Elizabeth E. Ebert

    Geosciences Websites

    Ebert, Beth

    the satellite estimates against independent data from rain gauges and radars. Standard measures such as bias on expected errors in rain location, type, mean and maximum intensities. Diagnostic validation approaches can of interest in this case is mean rain amount integrated over space and time (2.5° monthly rainfall

  11. Dark satellites and the morphology of dwarf galaxies

    CERN Preprints

    Helmi, Amina; Starkenburg, E; Starkenburg, T K; Vera-Ciro, C A; De Lucia, G; Li, Y -S

    2012-01-01

    One of the strongest predictions of the LambdaCDM cosmological model is the presence of dark satellites orbiting all types of galaxies. We focus here on the dynamical effects of such satellites on disky dwarf galaxies, and demonstrate that these encounters can be dramatic. Although mergers with M_sat > M_d are not very common, because of the lower baryonic content they occur much more frequently on the dwarf scale than for L_*-galaxies. As an example, we present a numerical simulation of a 20% (virial) mass ratio merger between a dark satellite and a disky dwarf (akin to the Fornax dwarf galaxy in luminosity) that shows that the merger remnant has a spheroidal morphology. We conclude that perturbations by dark satellites provide a plausible path for the formation of dSph systems and also could trigger starbursts in gas rich dwarf galaxies. Therefore the transition from disky to the often amorphous, irregular, or spheroidal morphologies of dwarfs could be a natural consequence of the dynamical heating of hithe...

  12. Probing the Epoch of Reionization with Milky Way Satellites

    CERN Preprints

    Muñoz, Joseph A; Loeb, Abraham; Diemand, Jürg

    2009-01-01

    While the connection between high-redshift star formation and the local universe has recently been used to understand the observed population of faint dwarf galaxies in the Milky Way (MW) halo, we explore how well these nearby objects can probe the epoch of first light. We construct a detailed, physically motivated model for the MW satellites based on the state-of-the-art Via Lactea II dark-matter simulations. Our model incorporates molecular hydrogen (H_2) cooling in low-mass systems and inhomogeneous photo-heating feedback during the internal reionization of our own galaxy. We find that the existence of MW satellites fainter than M_V ~ -5 is strong evidence for H_2 cooling in low-mass halos, while satellites with -5 > M_V > -9 were affected by hydrogen cooling and photoheating feedback. Most of the stars populating the brightest MW satellites could have formed after the epoch of reionization. Our models also predict a significantly larger dispersion in M_300 values than observed and a number of luminous sat...

  13. Luminous Satellites versus Dark Subhaloes: Clustering in the Milky Way

    CERN Preprints

    Bozek, Brandon; Gilmore, Gerard

    2013-01-01

    The observed population of the Milky Way satellite galaxies offer a unique testing ground for galaxy formation theory on small-scales. Our novel approach was to investigate the clustering of the known Milky Way satellite galaxies and to quantify the amount of substructure within their distribution using a two-point correlation function statistic in each of three spaces: configuration space, line-of-sight velocity space, and four-dimensional phase-space. These results were compared to those for three sets of subhaloes in the Via Lactea II Cold Dark Matter simulation defined to represent the luminous dwarfs. We found no evidence at a significance level above 2-sigma of substructure within the distribution of the Milky Way satellite galaxies in any of the three spaces. The "luminous" subhalo sets are more strongly clustered than are the Milky Way satellites in all three spaces and over a broader range of scales in four-dimensional phase-space. Each of the "luminous" subhalo sets are clustered as a result of subs...

  14. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    CERN Preprints

    Mogavero, F

    2015-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale $t_E$, which prevents mass and distance of the lens to be univocally determined. Gould (2013) has shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events ($t_E \\approx 20$ days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, $t_E \\approx 1$ day, dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite at even shorter timescales, $t_E \\approx 0.1$ days. A Fisher matrix analysis is employed to predict how the 1-sigma error on parallax depends on $t_E$ and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free-floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth...

  15. OUTREACH AT THE COOPERATIVE INSTITUTE FOR OCEANOGRAPHIC SATELLITE STUDIES

    Geosciences Websites

    Kurapov, Alexander

    in the College of Oceanic and Atmospheric Sciences (COAS) at Oregon State University (OSU), the Cooperative workshops related to its four Research Themes: Satellite Sensors and Techniques, Ocean-Atmosphere Fields and Fluxes, Ocean-Atmosphere Models and Data Assimilation, and Ocean-Atmosphere Analyses. CIOSS addresses

  16. An Integrated Evolutionary Model Approach to Small Satellite Engineering

    Engineering Websites

    framework. The development and use of a TDA for the FalconSAT-3 satellite is also described. The thesis presents several FalconSAT-3 operational events where the TDA was paramount in identifying products is demonstrated through the successful use of the FalconSAT-3 TDA in these events. DISCLAIMER

  17. A spectral comparison of (379) Huenna and its satellite

    MIT - DSpace

    DeMeo, Francesca E.

    We present near-infrared spectral measurements of Themis family Asteroid (379) Huenna (D ? 98 km) and its 6 km satellite using SpeX on the NASA IRTF. The companion was farther than 1.5? from the primary at the time of ...

  18. Orbit Maneuvers Through Inter-Satellite Forcing Michael C. Norman

    Engineering Websites

    Peck, Mason A.

    Orbit Maneuvers Through Inter-Satellite Forcing Michael C. Norman and Mason A. Peck Cornell-contacting spacecraft for orbit change and maintenance maneuvers. These types of forces are internal to the overall for the time derivatives of the orbital elements, we identify the relative configurations of the two spacecraft

  19. NASA Technical Paper 3394 Lifetimes of Lunar Satellite Orbits

    Physics Websites

    Rathbun, Julie A.

    NASA Technical Paper 3394 Lifetimes of Lunar Satellite Orbits Kurt W. Meyer The George Washington parking orbit issues. Additionally, we would also like to thank Robert Tolson of Tile George Washingt,e, est ions. #12;Summary Lifetimes of low-altitude lunar orbits are studied in this report to identify

  20. AVIATION UTILIZATION OF GEOSTATIONARY SATELLITES FOR THE AUGMENTATION TO

    Engineering Websites

    Stanford University

    AVIATION UTILIZATION OF GEOSTATIONARY SATELLITES FOR THE AUGMENTATION TO GPS: RANGING AND DATA LINK currently under development by the Federal Aviation Administration (FAA). WAAS will provide corrections to aviation users for the GPS clock, its ephemeris, and for the delay in its signal as it passes through

  1. Surface ages of mid-size Saturnian satellites

    CERN Preprints

    Di Sisto, Romina P

    2015-01-01

    The observations of the surfaces of the mid sized Saturnian satellites made by Cassini Huygens mission have shown a variety of features that allows study of the processes that took place and are taking place on those worlds. Research of the Saturnian satellite surfaces has clear implications for Saturn history and surroundings. In a recent paper, the production of craters on the mid sized Saturnian satellites by Centaur objects was calculated considering the current Solar System. We have compared our results with crater counts from Cassini images and we have noted that the number of observed small craters is less than our calculated number. In this paper we estimate the age of the surface for each observed terrain on each mid sized satellite of Saturn. We have noticed that since there are less observed small craters than calculated (except on Iapetus), this results in younger ages. This could be the result of efficient endogenous or exogenous process(es) for erasing small craters and or crater saturation at t...

  2. Tidal debris morphology and the orbits of satellite galaxies

    CERN Preprints

    Hendel, David

    2015-01-01

    How do galaxies move relative to one another? While we can examine the motion of dark matter subhalos around their hosts in simulations of structure formation, determining the orbits of satellites around their parent galaxies from observations is impossible except for a small number of nearby cases. In this work we outline a novel approach to probing the orbital distributions of infalling satellite galaxies using the morphology of tidal debris structures. It has long been understood that the destruction of satellites on near-radial orbits tends to lead to the formation of shells of debris, while those on less eccentric orbits produce tidal streams. We combine an understanding of the scaling relations governing the orbital properties of debris with a simple model of how these orbits phase-mix over time to produce a `morphology metric' that more rigorously quantifies the conditions required for shells to be apparent in debris structures as a function of the satellite's mass and orbit and the interaction time. U...

  3. Satellite-based estimates of groundwater depletion Matthew Rodell1

    Biology and Medicine Websites

    Chen, Zhongping

    LETTERS Satellite-based estimates of groundwater depletion in India Matthew Rodell1 , Isabella Velicogna2,3,4 & James S. Famiglietti2 Groundwater is a primary source of fresh water in many parts of the world. Some regions are becoming overly dependent on it, consuming groundwater faster than

  4. TCP SPLITTING PROTOCOL FOR BROADBAND AERONAUTICAL SATELLITE NETWORK

    Engineering Websites

    Baras, John S.

    of Maryland, College Park, MD 20742 Abstract In this paper, we recommend suitable transport protocols for an aeronautical network supporting Internet and data services via satellite. For the future IP-based aeronautical degraded performance of the Transport Protocol. Based on the observation that it is difficult for an end

  5. Huge "Structure" of Satellites Found Orbiting Milky Way

    Computer Technologies and Information Sciences Websites

    Fernandez, Eduardo

    Huge "Structure" of Satellites Found Orbiting Milky Way Grouping of galaxies puts cosmology;Cosmology in "Shambles"? According to the standard theory of galaxy formation, dark matter to completely and utterly rethink cosmology," Kroupa said. "Cosmology is basically in a shambles now." Dark

  6. Adaptive Satellite Attitude Control in the Presence of

    Engineering Websites

    Dixon, Warren

    matrix and unknown dynamic and static friction effects in the control moment gyroscope (CMG) gimbalsAdaptive Satellite Attitude Control in the Presence of Inertia and CMG Gimbal Friction controller is designed in this paper that compensates for dynamic uncertainties in the spacecraft inertia

  7. Satellite observation of dehydration in the Arctic Polar stratosphere

    Geosciences Websites

    Pan, Laura

    Satellite observation of dehydration in the Arctic Polar stratosphere L. L. Pan,1 W. J. Randel,1 H 2002. [1] We report the first space-borne observation of dehydration in the Arctic polar stratosphere Stratospheric Cloud (PSC) events. Furthermore, simultaneous observations of HNO3 and H2O show that the gas phase

  8. SLOT ALLOCATION IN A TDMA SATELLITE SYSTEM: SIMULATED

    Engineering Websites

    SLOT ALLOCATION IN A TDMA SATELLITE SYSTEM: SIMULATED ANNEALING APPROACH T. Toker , E. Altman , J describe here a heuristic solution based on simulated annealing. We further investigate how to improve the performance of the simulated annealing and the rate of convergence of the an- nealing. Numerical

  9. Because of its excellence in satellite-based research,

    Geosciences Websites

    Kurapov, Alexander

    's surface. By collecting measurements over time, oceanographers can see patterns that indicate circulation in satellite remote sensing. Mike Freilich helped design the scatterometer; he and Dudley Chelton are international leaders in analysis of scatterometer ocean surface winds. Chelton has led in designing altimeters

  10. A Satellite Survey Cloud Cover and Water Vapor

    Physics Websites

    A Satellite Survey of Cloud Cover and Water Vapor in Northern Chile A study conducted for: Cerro;EXECUTIVE SUMMARY Cloud cover and water vapor conditions in Northern Chile have been surveyed using fifty. An aerial mapping of cloud and water vapor has resulted in the identification of preferred areas

  11. SWOT: The Surface Water & Ocean Topography Satellite Mission

    Engineering Websites

    SWOT: The Surface Water & Ocean Topography Satellite Mission Doug Alsdorf Byrd Polar Research-Boundary Issues: ex: Tigris & Euphrates Disputes Slide courtesy Frank Schwartz n Water Usage: n 98.5% water effectively controls both rivers n Remote measurements of surface water volumes and fluxes creates free

  12. Global assessment of ocean carbon export by combining satellite observations

    Environmental Sciences and Ecology Websites

    Siegel, David A.

    cycle. Here we introduce a mechanistic assessment of the global ocean carbon export using satellite are a central component of the global carbon cycle through their storage, transport, and transformations production (NPP) [Laws et al., 2000; Dunne et al., 2005; H11] or by using global coupled carbon cycle

  13. FORMATION FLYING SATELLITE CONTROL UTILIZING INPUT SHAPING Erika Biediger

    Engineering Websites

    Singhose, William

    of the current work is to enhance the existing formation flying technologies by integrating input shaping Bang-Bang,2 linearized feedback coupled with model predictive control,3 and PD control.4 The control: Coordinate Frame Geometry. Although many control algorithms model satellites as a point mass, more accurate

  14. State Vector Determination By A Single Tracking Satellite

    Astrophysics (arXiv)

    Kerry M. Soileau

    2007-05-08

    Using only a single tracking satellite capable of only range measurements to an orbiting object in an unknown Keplerian orbit, it is theoretically possible to calculate the orbit and a current state vector. In this paper we derive an algorithm that can perform this calculation.

  15. yclone Tracking using Multiple Satellite Image Sources Anand Panangadan

    Biology and Medicine Websites

    Panangadan, Anand

    yclone Tracking using Multiple Satellite Image Sources Anand Panangadan Jet Propulsion Laboratory.V.Panangadanshen.shyang.hoAshit.Talukder}@jpl.nasa.gov Shen-Shyang Ho Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 Ashit Talukder Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 ABSTRACT We present

  16. Growth of Galactic Bulges by Mergers: I. Dense Satellites

    Astrophysics (arXiv)

    J. A. L. Aguerri; M. Balcells; R. F. Peletier

    2000-12-07

    Andredakis, Peletier & Balcells (1995) fit Sersic's law $\\mu(r) \\sim r^{1/n}$ to the bulges of the Balcells & Peletier (1994) galaxy sample, and infer that $n$ drops with morphological type T from $n \\approx$ 4--6 for S0 to $n=1$ (exponential) for Sc's. We use collisionless N body simulations to test the assumption that initially the surface brightness profiles of all bulges were exponential, and that the steepening of the profiles toward the early-types is due to satellite accretion. The results are positive. After the accretion of a satellite, bulge-disk fits show that the bulge grows and that the bulge profile index $n$ increases proportional to the satellite mass. For a satellite as massive as the bulge, $n$ rises from 1 to 4. We present kinematic diagnostics on the remnants and disk thickening. The latter suggests that the bulge growth must have occurred before the last formation of a thin disk in the galaxy. The thick disks created by the merger are reminiscent of thick disks seen in early-type edge-on galaxies. The efficiency of the process suggests that present day bulges of late-type spirals showing exponential profiles cannot have grown significantly by collisionless mergers.

  17. RNS Implementation of High Performance Filters for Satellite Demultiplexing

    Computer Technologies and Information Sciences Websites

    Nannarelli, Alberto

    RNS Implementation of High Performance Filters for Satellite Demultiplexing G.C. Cardarilli, A. Del we present a Residue Number System (RNS) implementation of digital filters to be used for space applications. The RNS is particularly attractive because of the reduced power dissipation with respect

  18. Core Flow Modelling using CHAMP Satellite Vector Data

    Geosciences Websites

    #12;Overview · Motive / Background · Core Flow modelling ­ Method ­ Data · Ground Observatories · Satellite Measurements · Virtual Observatories ­ Results · Core Flows · Residuals · Future Work #12;Secular by the motion of liquid iron in the Earth's outer core ­ fluid flow is unpredictable over long periods of time

  19. Cyclone Global Navigation Satellite System (CYGNSS) Mission Overview

    Engineering Websites

    Eustice, Ryan

    _Handout The CYGNSS mission is comprised of 8 Low Earth Orbiting (LEO) spacecraft (S/C) that receive both direct-resolutionwindfieldimageryofTCgenesis,intensificationanddecay. GPS satellites CYGNSS Observatories Primary Objectives: · Measure ocean surface wind speed in all System (CYGNSS) Mission Timeline Delay Mapping Receiver (DMR) Delay Doppler Mapping Instrument (DDMI)Observatory

  20. Cognitive Vision for Autonomous Satellite Rendezvous and Docking

    Computer Technologies and Information Sciences Websites

    Terzopoulos, Demetri

    with the challenge of effec- tively combining low-level vision with artificial intelli- gence. Some of the earliestCognitive Vision for Autonomous Satellite Rendezvous and Docking Faisal Z. Qureshi and Demetri MDRobotics Limited, Brampton, ON L6S 4J3, Canada Abstract We present a cognitively-controlled vision system