M Parigi , A. Cooper, C. Fellows - University of New England.
Abstract
Aims: We study the link between symmetry of the geomorphology of Imhotep and the current and probable past rotational state of comet 67P/Churyumov-Geramisenko. We provide constraints on how symmetry can be explained on such a complex cometary substrate. We see whether layering, strength, slopes, subsidence - observed and calculated in recent papers is consistent with new novel explanations of sliding, delaminating layers.
Methods: We computed the axis of symmetry on Imhotep and extrapolated the plane around to other regions of the comet, such as Hatmehit to study whether the symmetry continued. We then compared the best fit planes of symmetry with the rotational plane, the long axis, and the short axis of the nucleus and temporal changes on Imhotep. We compare erosion explanations with never before hypothesised horizontal sliding explanations both with consistency with measured material properties and whether the explanation fits the morphological and subsidence evidence better than (recent historical) erosional explanations.
Results: The axes of symmetry show a remarkable connection with the long and short axes of the nucleus. Consequent higher resolution analysis of cliff edges represented by this symmetry demonstrates matching features not explainable by erosion. Evidence connected with this and observed subsidence, material strengths and slopes, together provides very strong evidence for sliding, delaminating layers.
