Coronal Radio Sounding Experiments with Mars Express: Scintillation Spectra during Low Solar Activity

Journal Article · Thu Mar 25 00:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3395973· OSTI ID:21371736

Efimov, A I; Lukanina, L A; Samoznaev, L N; Rudash, V K ^[1]; Chashei, I V ^[2]; Bird, M K ^[3]; Paetzold, M; Tellmann, S ^[4]

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1. Kotel'nikov Inst. Radio Engg. and Electronics, Russian Acad. Science, 125009 Moscow (Russian Federation)
2. Lebedev Phys. Inst., Russian Acad. Science, 117924 Moscow (Russian Federation)
3. Argelander-Institut fuer Astronomie, Univ. Bonn, 53121 Bonn (Germany)
4. Rheinisches Institut fuer Umweltforschung, Univ. Koeln, 50931 Koeln (Germany)

Coronal radio sounding observations were carried out with the radio science experiment MaRS on the ESA spacecraft Mars Express during the period from 25 August to 22 October 2004. Differential frequency and log-amplitude fluctuations of the dual-frequency signals were recorded during a period of low solar activity. The data are applicable to low heliographic latitudes, i.e. to slow solar wind. The mean frequency fluctuation and power law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The radial dependence of the frequency fluctuation spectral index alpha reflects the previously documented flattening of the scintillation power spectra in the solar wind acceleration region. Temporal spectra of S-band and X-band normalized log-amplitude fluctuations were investigated over the range of fluctuation frequencies 0.01 Hz<nu<0.5 Hz, where the spectral density is approximately constant. The radial variation of the spectral density is analyzed and compared with Ulysses 1991 data, a period of high solar activity. Ranging measurements are presented and compared with frequency and log-amplitude scintillation data. Evidence for a weak increase in the fractional electron density turbulence level is obtained in the range 10-40 solar radii.

• OSTI ID: 21371736
• Journal Information: AIP Conference Proceedings, Vol. 1216, Issue 1; Conference: 12. international solar wind conference, Saint-Malo (France), 21-26 Jun 2009; Other Information: DOI: 10.1063/1.3395973; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCELERATION
ASTROPHYSICS
ELECTRON DENSITY
FLUCTUATIONS
SCINTILLATIONS
SOLAR CORONA
SOLAR RADIO BURSTS
SOLAR WIND
SPACE VEHICLES
SPECTRAL DENSITY
TURBULENCE
ATMOSPHERES
ELECTROMAGNETIC RADIATION
FUNCTIONS
PHYSICS
RADIATIONS
RADIOWAVE RADIATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SPECTRAL FUNCTIONS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR WINDS
VARIATIONS
VEHICLES