1996 FG3, MarcoPolo-R mission target: Living on the edge

199FG3 is a binary asteroid, the nominal target of the MarcoPolo-R mission [1]. Its mass, size, spin rate and satellite orbital period are well estimated. Radar observations (from Arecibo and Goldstone) have also provided estimates of the primary shape and maximum separation of the secondary. The fast spin rate of the primary make it an extremely interesting object from a mechanical point of view as it is at the limit of rotational stability against reshaping and/or mass loss. This rare circumstance gives an outstanding added value to the mission because it may provide constraints on the internal structure of the primary and the mechanisms of formation of binary asteroids. The working group on mechanical properties of the MP-R mission has analysed 1996FG3's peculiar characteristics from a theoretical standpoint and through analysis of numerical experiments. Our conclusions may have consequences on the design and landing site choice of this unique mission.