Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006dps....38.6804c&link_type=abstract
American Astronomical Society, DPS meeting #38, #68.04; Bulletin of the American Astronomical Society, Vol. 38, p.621
Astronomy and Astrophysics
Astronomy
Scientific paper
Asteroid regoliths can provide insight into the impact history, dynamical evolution, and surface processes on small objects. Infrared observations suggest that most asteroids, down to 1-2 km in size, have low thermal inertias consistent with the presence of regolith (e.g. Delbó et al., Icarus, 166, 116, 2003; Wolters et al., Icarus, 175, 92, 2005). Polarimetric radar imaging can be used to provide an independent assessment of regolith cover, and we discuss results for three near-Earth asteroids.
We use the Arecibo radar system to transmit a circularly polarized wave. If this wave refracts into an asteroid's surface, the vertically and horizontally linearly polarized components will be transmitted with different amplitudes. If the transmitted wave is reflected from a subsurface interface or from buried rocks, a net linearly polarized echo component will result. The magnitude and direction of this linear polarization are governed by the physical properties of the surface and by the orientation of the incident wave with respect to the surface normal. Asteroids with regolith cover may show a linearly polarized echo component, whereas high-dielectric bare-rock surfaces will lead to predominately surface reflections.
We have used this technique to search for regolith on the asteroids 1999 JM8, 4179 Toutatis, and 2004 VG64. Images of the linearly polarized echo component for 1999 JM8 show clear evidence for subsurface scattering, and we infer that the asteroid is covered in regolith. The 4179 Toutatis data show a somewhat smaller linearly polarized echo component; the smaller values may be due to the complicated shape and viewing geometry. 2004 VG64 is close to spherical, which will allow for a more straightforward analysis. These results are part of a larger project to study the radar polarimetric properties of a small sample of near-Earth asteroids. This project is funded by the NASA Planetary Astronomy program.
Campbell Don B.
Carter Lynn Marie
Nolan Michael C.
No associations
LandOfFree
Regolith Cover on Near-Earth Asteroids: Radar Polarimetric Imaging and Analysis does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Regolith Cover on Near-Earth Asteroids: Radar Polarimetric Imaging and Analysis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Regolith Cover on Near-Earth Asteroids: Radar Polarimetric Imaging and Analysis will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1078168