Towards a high-accuracy geological model of the 67P comet

It was recently shown that the layered structure of each of the two lobes of comet 67P/Churyumov-Gerasimenko (67P) can be modelled as a set of concentric ellipsoidal shells. The ellipsoidal model is able to correctly predict the major layering-related features on the comet surface; however, the ellipsoidal model is a first order approximation of a more complex internal structure. A better description of this latter requires an improved model. In this contribution preliminary results in building a refined three-dimensional model of the comet are presented with focus on the Small Lobe. The model is realized using a 3D geo-modeling technique that embeds linear and planar features (layer joints and terraces) as well as other geometric characteristics (e.g. vectorial fields) as constraints, influencing the reconstruction of the comet layered structure. Results allow accounting for features that are not predicted by the ellipsoidal model, therefore such refined 3D model is a step towards a model of the comet nucleus that may clues useful in unraveling the complex history that shaped it to its present configuration.