The layered structure of the nucleus of the comet 67P: implications on missing volumes and lobes orientations

The OSIRIS cameras onboard Rosetta revealed that each lobe of comet 67P/Churyumov-Gerasimenko (67P) is characterized by a deep layering that can be modelled as sets of concentric ellipsoidal shells. We present several implications of this geological model that can be useful to shed light on the evolution of the planetesimal. The model allows to estimate that more than the 50% of the original material forming the comet is now missing. Furthermore the geological models of the two lobes appear to have their axes consistently aligned, possibly helping to better understand the dynamics of the low velocity impact that merged two independent planetesimals into a single bilobate body.