Geomorphology of the Imhotep region on comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Abstract

Context. Since August 2014, the OSIRIS Narrow Angle Camera (NAC) onboard the Rosetta spacecraft has acquired high spatial resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko, up to the decimeter scale. This paper focuses on the Imhotep region, located on the nucleus largest lobe, near the equator. Aims. We performed the mapping, inventory and description of the geomorphology of the Imhotep region. We propose and discuss some processes to explain the formation and on-going evolution of this region. Methods. We use OSIRIS NAC images, gravitational heights and slopes and Digital Terrain Models (DTM) to map and measure the morphologies of Imhotep. Results. The Imhotep region presents a wide variety of terrains and morphologies: smooth and rocky terrains, bright areas, linear features, roundish features and boulders. Gravity processes play a significant role on the geomorphological evolution of this region by mass wasting and collapse. Cometary processes initiate erosion and are responsible for the formation of degassing conduits revealed by elevated roundish features on the surface. A scenario for the formation and evolution of the Imhotep region is also proposed, which implies the presence of large primordial voids into the nucleus, resulting from its formation process.