Program: GN-2010B-Q-99

We propose to observe 9 known multiple asteroid systems with Gemini/ALTAIR at their opposition to refine the mutual orbits of their satellites. We analyzed and gathered all adaptive optics observations collected over the past 10 years from VLT and Gemini telescopes, plus all Hubble Space Telescope in a database called VOBAD. From 2003-2007 data, we published a preliminary study of 12 multiple asteroid systems assuming Keplerian orbits and derived their mass and average bulk densities. Using a recently developed dynamical model, we will incorporate these new Gemini/ALTAIR astrometric positions (4-6 obs per asteroids) to build a consistent orbital solution for these systems. This large temporal baseline will allow us to detect non-Keplerian perturbations introduced by resonances, estimate the mass of the moonlets, the distribution of material in the interior of the primary bringing the study of these multiple asteroid systems to an exquisite level of detail and allowing us to provide ephemeris calculations. This work will help understanding the formation of these mysterious multiple asteroid systems.