FUTURE IN-SITU EXPLORATION OF A RELICT OCEAN WORLD: ASSESSMENT OF POTENTIAL LANDING AND SAMPLING SITES FOR AN IN-SITU MISSION TO CERES

Ceres is the most water-rich body in the inner Solar System, after Earth. An ancient subsurface ocean frozen early in the dwarf planet’s history, and materials derived from the ocean are visible on the surface today (Castillo-Rogez+ 2018). An extant deep brine reservoir at the crust/mantle boundary is formed by remnants of the ancient oceanic liquid (Castillo-Rogez+ 2019). There is great interest in sending an in-situ mission to Ceres because Dawn’s orbital exploration revealed it to be a complex relict ocean world with astrobiological relevance (Castillo-Rogez+ 2020a). The Ceres Planetary Mission Concepts Study (PMCS) aims to asses Ceres’ past and current habitability and determine Ceres’ origin, which require detailed in-situ or returned sample compositional measurements (Castillo-Rogez+ 2020b). Thus, future exploration of Ceres by an in-situ lander and/or sample return will require a detailed understanding of the surface. By analyzing the highest resolution Dawn data (approx. ≧5 m/pix in Occator and ≧35 m/pix globally), we show that scientifically compelling landing/sampling sites are present in three potential landing/sampling regions: Occator crater, Haulani crater and Ahuna Mons. While hazards are present (slopes >10°, fractures, pitted terrain and boulders), safe sites likely exist, such as at Occator’s Vinalia Faculae. An orbital reconnaissance phase (to identify hazards smaller than resolved by Dawn) combined with terrain relative navigation would be the least risky way for a future mission to land and/or collect a sample. The ability to land precisely (within a ≦100 m diameter circle) enables in-situ exploration because many 100 m diameter potential landing/sampling sites are present within each landing/sampling region (e.g. >800,000 landing sites in Occator). Thus, it is highly probable that at least one site would be a safe and scientifically compelling site in which to continue our exploration of this relict ocean world from its surface. Thank you to the Ceres PMCS team for the discussions that aided in developing this work. Part of this work was funded by NASA under grant NNH18ZDA001N-PMCS. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Government sponsorship acknowledged.