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Title: Constraining the physical properties of near-Earth object 2009 BD

We report on Spitzer Space Telescope Infrared Array Camera observations of near-Earth object 2009 BD that were carried out in support of the NASA Asteroid Robotic Retrieval Mission concept. We did not detect 2009 BD in 25 hr of integration at 4.5 μm. Based on an upper-limit flux density determination from our data, we present a probabilistic derivation of the physical properties of this object. The analysis is based on the combination of a thermophysical model with an orbital model accounting for the non-gravitational forces acting upon the body. We find two physically possible solutions. The first solution shows 2009 BD as a 2.9 ± 0.3 m diameter rocky body (ρ = 2.9 ± 0.5 g cm{sup –3}) with an extremely high albedo of 0.85{sub −0.10}{sup +0.20} that is covered with regolith-like material, causing it to exhibit a low thermal inertia (Γ=30{sub −10}{sup +20} SI units). The second solution suggests 2009 BD to be a 4 ± 1 m diameter asteroid with p{sub V}=0.45{sub −0.15}{sup +0.35} that consists of a collection of individual bare rock slabs (Γ = 2000 ± 1000 SI units, ρ=1.7{sub −0.4}{sup +0.7} g cm{sup –3}). We are unable to rule out either solution based on physicalmore » reasoning. 2009 BD is the smallest asteroid for which physical properties have been constrained, in this case using an indirect method and based on a detection limit, providing unique information on the physical properties of objects in the size range smaller than 10 m.« less
Authors:
;  [1] ; ; ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Physics and Astronomy, Northern Arizona University, P.O. Box 6010, Flagstaff, AZ 86011 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 65, Cambridge, MA 02138-1516 (United States)
  3. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  4. Institute of Astronomy, Charles University, V Holešovičkách 2, CZ-18000, Prague 8 (Czech Republic)
  5. SRON Netherlands Institute for Space Research, Postbus 800, 9700-AV Groningen (Netherlands)
  6. DLR Institute of Planetary Research, Rutherfordstrasse 2, D-12489 Berlin (Germany)
Publication Date:
OSTI Identifier:
22356903
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTEROIDS; FLUX DENSITY; MATHEMATICAL SOLUTIONS; MOMENT OF INERTIA; NASA; OVERBURDEN; PHYSICAL PROPERTIES; PLANETS; PROBABILISTIC ESTIMATION; SENSITIVITY; SPACE; TELESCOPES