An overview of the LIDAR observations of asteroid 25143 Itokawa

We present an overview of the laser altimeter(LIDAR) results for asteroid 25143 Itokawa. The trace of a 7 × 12-m elliptical beam spot made it possible to determine the local surface topography with an accuracy of a few meters in altitude, from a home position roughly 7 km above the surface. Sequential detection of the altitude of the spacecraft during two orbital spans of descent for sampling allowed determination of the asteroid mass as 3.58 × 1010 kg ± 5% and 3.54 × 1010 kg ± 6%, which are consistent with the most probable mass estimate of 3.51 × 1010 kg ± 3% given by Fujiwara et al. [Fujiwara, A., Kawaguchi, J., Yeomans, D.K. et al., 2006. The rubble-pile asteroid Itokawa as observed by Hayabusa. Science 312, 1330–1334]. Together with the total volume of the asteroid deduced from a shape model (i.e., 1.84 × 107 m3 ± 3%), this estimate by LIDAR suggests that asteroid Itokawa has a low density of 1.9 g/cm3 ± 9% and a high bulk porosity of about 40%.