Journal Article

Extensive water ice within Ceres’ aqueously altered regolith

Feldman, W. C., Lawrence, D. J., Raymond, C. A., Forni, O., Toplis, M. J., Prettyman, T. H., Yamashita, N., Ehlmann, B. L., Rayman, M. D., Joy, S. P., Sizemore, H. G., Schörghofer, N., Ammannito, E., Russell, C. T., Castillo-Rogez, J., McSween, H. Y., Polanskey, C. A., Marchi, S.

2017

Overview

The surface elemental composition of dwarf planet Ceres constrains its regolith ice content, aqueous alteration processes, and interior evolution. Using nuclear spectroscopy data acquired by NASA’s Dawn mission, we determined the concentrations of elemental hydrogen, iron, and potassium on Ceres. The data show that surface materials were processed by the action of water within the interior. The non-icy portion of Ceres’ carbon-bearing regolith contains similar amounts of hydrogen to those present in aqueously altered carbonaceous chondrites; however, the concentration of iron on Ceres is lower than in the aforementioned chondrites. This allows for the possibility that Ceres experienced modest ice-rock fractionation, resulting in differences between surface and bulk composition. At mid-to-high latitudes, the regolith contains high concentrations of hydrogen, consistent with broad expanses of water ice, confirming theoretical predictions that ice can survive for billions of years just beneath the surface.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science,American Association for the Advancement of Science (AAAS)
• Subject: Astronomy / Astrophysics / Carbonaceous chondrites / Ceres asteroid / Chemical composition / Concentration (composition) / Data acquisition / Dichroism / Dwarf planets / Earth Sciences / Equator / Fractionation / Gamma rays / Hydrogen / Ice / Inner solar system / Iron / Physics / Planetary composition / Planets / Regolith / Rocks / Sciences of the Universe / Solar system / Spacecraft / Spectroscopy / Spectrum analysis / Water