Gaia observations of asteroids:: Sizes, taxonomy, shapes and spin properties

Extensive simulations of the predicted performances of Gaia as a powerful tool to determine physical properties of asteroids are currently being performed by several teams working in the Gaia Solar System Working Group. Gaia is expected to produce a major breakthrough in asteroid science. Among several outstanding results we can expect from this mission, there are direct determinations of masses and sizes (and hence average densities), a new taxonomic classification, and derivations of spin properties and overall shapes for a substantial sample of objects. Current state-of-the-art of the simulations, dealing with the derivation of sizes, taxonomy and spin properties, is briefly reviewed. The importance and the implications of the expected results are also discussed.