Landslides on Comet 67P/Churyumov-Gerasimenko

Mass movements are almost ubiquitous in the Solar System, with rockfall, avalanches or landslides that are observed not only on Earth, but also on multiple other bodies. The characteristics of the observed landslides (i.e. type of failure, geometry, velocity, etc.) are strongly influenced by several factors such as the initial mass position, the material and its mechanical properties, the topographic relief and the volatile content. In this work, we identified 26 landslides located on the surface of the comet 67P using OSIRIS Rosetta images. We investigate the landslide shapes and aspect ratios through the use of the high-resolution shape model of 67P. Assuming the height to runout length as an approximation for the friction coefficient of the cometary material, we find that the mapped mass failures behaves thoroughly different from the one observed on other Solar System icy bodies. Indeed, being the 67P high friction coefficients comparable, or even higher, than those found on Earth landslide, they imply a mechanically rocky-type behavior for the cometary material. This makes 67P, and comets in general, very peculiar objects that are mainly composed of ice and organics, but that are characterized by rocky-type properties rather than icy-type characteristics.