Is astrometry enough? Deflection relevant Near Earth Object characterization efforts in Europe

International audienceESA's Gaia mission heralds a new era in the field of astrometry. In particular, solar system science will not only benefit from an unprecedented precision of direct observations of objects by the Gaia satellite, the Gaia astrometric catalog is going to improve the accuracy of ground based measurements far beyond the mission's lifetime. The ensuing boost in the quality of astrometric data grants, for instance, access to detecting weak non-gravitational accelerations experienced by solar system objects. Those, in turn, are vital for long term ephemeris calculations and especially for asteroid impact probability estimates.Accurately measuring non-gravitational drift rates is only half the battle, though. Convincingly linking model predictions for non-gravitational effects with the motion of minor planets constitutes the other half, as such a link requires a deep understanding of the shape, spin state and physical properties of minor planets. In this contribution I discuss the requirements on the physical characterization of asteroids for an accurate long term prediction of orbits, the calculation of collision probabilities with terrestrial planets, as well as a successful asteroid deflection should it become necessary. Moreover, current European efforts to procure such data for potentially hazardous asteroids are presented