Surface water-ice deposits in the northern shadowed regions of Ceres

Abstract

Ceres, a dwarf planet located in the main asteroid belt, has a low bulk density 1 , and models predict that a substantial amount of water ice is present in its mantle and outer shell 2–4 . The Herschel telescope and the Dawn spacecraft 5 have observed the release of water vapour from Ceres 6,7 , and exposed water ice has been detected by Dawn on its surface at mid-latitudes 8 . Water molecules from endogenic and exo- genic sources can also be cold-trapped in permanent shad- ows at high latitudes 9–11 , as happens on the Moon 12,13 and Mercury 14,15 . Here we present the first image-based survey of Ceres’s northern permanent shadows and report the discov- ery of bright deposits in cold traps. We identify a minimum of 634 permanently shadowed craters. Bright deposits are detected on the floors of just 10 of these craters in multi- scattered light. We spectroscopically identify one of the bright deposits as water ice. This detection strengthens the evidence that permanently shadowed areas have preserved water ice on airless planetary bodies.