Shantanu P. Naidu, Jean-Luc Margot, Michael W. Busch, Patrick A. Taylor, Michael C. Nolan, Ellen S. Howell, Marina Brozovic, Lance A. M. Benner, Jon D. Giorgini, Christopher Magri
We observed near-Earth asteroid (162421) 2000 ET70 using the Arecibo and Goldstone radar systems over a period of 12 days during its close approach to the Earth in February 2012. We obtained continuous wave spectra and range-Doppler images with range resolutions as fine as 15 m. Inversion of the radar images yields a detailed shape model with an effective resolution of 100 m. The asteroid has overall dimensions of 2.6 km X 2.2 km X 2.1 km and a surface rich with kilometer-scale ridges and concavities. It is a principal axis rotator and spins in a retrograde manner with a spin period of 8.96 +/- 0.02 hours. In terms of gravitational slopes evaluated at scales of 100 m, the surface seems mostly relaxed with over 99% of the surface having slopes less than 30 degrees, but there are some outcrops at the north pole that may have steeper slopes. Our precise measurements of the range and velocity of the asteroid, combined with optical astrometry, enables reliable trajectory predictions for this potentially hazardous asteroid in the interval 460-2813.
View original:
http://arxiv.org/abs/1301.6655
No comments:
Post a Comment