Author/Authors :
Busch، نويسنده , , Michael W. and Ostro، نويسنده , , Steven J. and Benner، نويسنده , , Lance A.M. and Brozovic، نويسنده , , Marina and Giorgini، نويسنده , , Jon D. and Jao، نويسنده , , Joseph S. and Scheeres، نويسنده , , Daniel J. and Magri، نويسنده , , Christopher and Nolan، نويسنده , , Michael C. and Howell، نويسنده , , Ellen S. and Taylor، نويسنده , , Patrick A. and Margot، نويسنده , , Jean-Lu، نويسنده ,
Abstract :
We observed the near-Earth ASTEROID 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 ± 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid’s equator that is broken by a concavity about 150 m in diameter. Otherwise the asteroid’s surface is notably smooth on decameter scales. EV5’s radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.
Keywords :
Asteroids , Asteroids , Asteroids , Dynamics , Radar observations , surfaces
