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Physical properties of near-Earth Asteroid (33342) 1998 WT24 |
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| Authors: | Michael W Busch Lance AM Benner Jon D Giorgini Randy Rose Christopher Magri Michael C Nolan |
| Institution: | a Division of Geological and Planetary Sciences, California Institute of Technology, MC 150-21, Pasadena, CA 91125, USA b Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA c Department of Aerospace Engineering, University of Michigan, 1320 Beal Avenue, Ann Arbor, MI 48109, USA d University of Maine at Farmington, Preble Hall, 173 High St., Farmington, ME 04938, USA e Department of Astronomy, Cornell University, 304 Space Sciences Bldg., Ithaca, NY 14853, USA f Arecibo Observatory, National Astronomy and Ionosphere Center, Box 995, Arecibo, PR 00613, USA |
| Abstract: | During its close Earth approach in 2001, the E-class near-Earth Asteroid (33342) 1998 WT24 was the focus of extensive radar, optical, and thermal infrared observations. We present a physical model of this object, estimated from Arecibo and Goldstone radar images that cover multiple rotations and span over 100° of sky motion. The asteroid has an equivalent diameter of 415±40 m and a diffuse radar scattering law that is identical in both senses of circular polarization, implying a surface that is extremely rough on centimeter-to-decimeter scales. The shape is dominated by three large basins, which may be impact craters or a relic of past dynamical disruption of the object. Analysis of YORP perturbations on WT24's spin state predicts that the asteroid's spin rate is decreasing at a rate of  . Simply extrapolating this rate suggests that the asteroid will despin over the next 150 kyr and was spinning at its surface disruption rate 75 kyr ago, but the rotational evolution of WT24 depends on the surface's thermal properties and probably is more complex than a simple spin-down. |
| Keywords: | Asteroids composition Asteroids dynamics |
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