Determining asteroid spin states using radar speckles
Abstract
Knowing the shapes and spin states of near-Earth asteroids is essential to understanding their dynamical evolution because of the Yarkovsky and YORP effects. Delay-Doppler radar imaging is the most powerful ground-based technique for imaging near-Earth asteroids and can obtain spatial resolution of <10 m, but frequently produces ambiguous pole direction solutions. A radar echo from an asteroid consists of a pattern of speckles caused by the interference of reflections from different parts of the surface. It is possible to determine an asteroid's pole direction by tracking the motion of the radar speckle pattern. Speckle tracking can potentially measure the poles of at least several radar targets each year, rapidly increasing the available sample of NEA pole directions. We observed the near-Earth asteroid 2008 EV5 with the Arecibo planetary radar and the Very Long Baseline Array in December 2008. By tracking the speckles moving from the Pie Town to Los Alamos VLBA stations, we have shown that EV5 rotates retrograde. This is the first speckle detection of a near-Earth asteroid.
Additional Information
© 2010 Elsevier Inc. Received 9 March 2010; revised 5 May 2010; accepted 12 May 2010. Available online 19 May 2010. The NRAO Socorro & Green Bank, Goldstone Solar System Radar, and NAIC Arecibo staff helped to obtain the data presented here. A. Galad, B.W. Koehn, and M.D. Hicks observed EV5 optically and determined its rotation rate. J.-L. Margot and C. Magri provided very helpful reviews. A.T. Deller and R.C. Walker provided helpful technical comments. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation. Some of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). This paper is based in part on work funded by NASA under the Science Mission Directorate Research and Analysis Programs. M.W. Busch was supported by the Hertz Foundation.Attached Files
Supplemental Material - mmc1.pdf
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Additional details
- Eprint ID
- 20462
- Resolver ID
- CaltechAUTHORS:20101021-094221061
- NASA
- Fannie and John Hertz Foundation
- Created
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2010-10-25Created from EPrint's datestamp field
- Updated
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2023-01-20Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences