Ceres as seen by VIR/ Dawn: spectral modeling and laboratory measurements suggest altered and pristine silicates within carbon chemistry

Abstract

The NASA/Dawn mission has acquired an unprecedented amount of data from the surface of the dwarf planet Ceres, providing a thorough characterization of its surface composition. The current favorite compositional model includes a mixture of ultra-carbonaceous material, phyllosilicates, carbonates, organic, Fe-oxides, and volatiles, as determined by the Dawn/VIR-IR imaging spectrometer, with the constraints on the elemental composition provided by the Dawn/GRAND instrument. The recent calibration of the VIS channel of the VIR spectrometer provided further constraints on the overall compositional model, suggesting another type of silicate not previously considered. This work reviews the VIR-VIS calibration process, and the resulting compositional model of Ceres surface considering both VIS and IR channels. Laboratory experiments are needed for a better understanding of the global (VIS-IR) shape of Ceres average surface, and in particular for the interpretation of the emergent absorption at 1{\mu}m. Current and future experiments are also discussed in this work.