SPHERE Sheds New Light on the Collisional History of Main-belt Asteroids

International audienceThe Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument has unveiled unprecedented details of the three-dimensional shape, surface topography and cratering record of four medium-sized ( 200 km) asteroids, opening the prospect of a new era of ground-based exploration of the asteroid belt. Although two of the targets, (130) Elektra and (107) Camilla, have been observed extensively for more than fifteen years by the first-generation adaptive optics imagers, two new moonlets were discovered around these targets, illustrating the unique power of SPHERE. In the next two years SPHERE will continue to collect high- angular-resolution and high-contrast measurements of about 40 asteroids. These observations of a large number of asteroids will provide a unique dataset to better understand the collisional history and multiplicity rate of the asteroid belt