Solar System data mining for Gaia and ground-based observational support

International audienceThe Gaia mission will observe between 2.5 and 3x105 Solar System objects. Most of them will be asteroids. As described elsewhere (Cellino et al. 2007, Tanga et al. 2007, Mignard et al. 2008) Gaia will provide a complete dynamical and physical characterisation of these bodies, that has no comparisons with the datasets ever obtained by a single groundor spacebased telescope. In fact, high precision astrometry, flux measurements and spectra will be available in an homogeneous set of data. However, in order to fully exploit the scientific potential of the data, a dedicated processing structure is needed. For this reason, a specific data reduction and analysis pipeline is under development. Some aspects of the implementation require solving interesting challenges in Solar System dynamics, consisting in new and more complex formulations of classic problems. We discuss, in particular, the determination of asteroid masses and the measurement of non-gravitational forces. Also, we show that - in the case of Solar System objects - the high astrometric accuracy of Gaia cannot completely rule out the use of ground-based data for increasing the extent of the final mission products. Well planned and focused preand post-mission observational campaigns could thus greatly help to reach goals situated at the edge (or beyond) the reach of Gaia observations alone. References Cellino, A., Tanga, P., Dell'Oro, A., Hestroffer, D. 2007. Asteroid science with Gaia: Sizes, spin properties, overall shapes and taxonomy. Adv. Space Res. 40 (2), 202-208 Mignard, F.,Cellino, A., Muinonen, K., Tanga, P., Delbo, D., Dell'Oro, A., Granvik, M., Hestroffer, D., Mouret, S., Thuillot, W., Virtanen, J. 2008. The Gaia mission: expected applications to asteroid science. Earth Moon and Planets, in press Tanga, P., Hestroffer, D., Cellino, A., Mignard, F. 2007. Gaia observations of Solar System objects: Impact on dynamics and ground-based observations. Adv. Space Res. 40 (2), 209-21