Exposed H2O-rich areas detected on Ceres with the dawn visible and infrared mapping spectrometer

• Published in: Icarus (New York, N.Y. 1962) Vol. 318; pp. 22 - 41
• Main Authors: Combe, Jean-Philippe, Raponi, Andrea, Tosi, Federico, De Sanctis, Maria Cristina, Carrozzo, Filippo Giacomo, Zambon, Francesca, Ammannito, Eleonora, Hughson, Kynan H.G., Nathues, Andreas, Hoffmann, Martin, Platz, Thomas, Thangjam, Guneshwar, Schorghofer, Norbert, Schröder, Stefan, Byrne, Shane, Landis, Margaret E., Ruesch, Ottaviano, McCord, Thomas B., Johnson, Katherine E., Singh, Sandeep Magar, Raymond, Carol A., Russell, Christopher T.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15-01-2019
• Subjects: Dwarf planet Ceres; Exposed H2O ice; Reflectance spectroscopy; Surface composition; Reflectance spectroscopy; Surface composition; Exposed H2O ice; Dwarf planet Ceres
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2017.12.008

•Exposed H2O-rich materials at Ceres’ surface have been detected in VIR spectra at 9 different locations.•H2O ice is the component that most likely explains the H2O detections in the spectra.•All H2O absorption features are detected at latitudes above 30° and over areas of a few km2 at most.•Exposed ice is rare, even though subsurface ice is ubiquitous.
H2O-rich materials are locally exposed at the surface of Ceres as discovered from infrared reflectance spectra of the Visible and InfraRed mapping spectrometer (VIR) of the Dawn mission. Nine locations on Ceres exhibit diagnostic absorption bands of the H2O molecule at 2.00, 1.65 and 1.28 µm. The detections are all consistent with H2O ice mixed with low-albedo components. All the reported H2O exposures occur at latitudes poleward of 30° in fresh craters near rim shadows, have a surface area < 7 km2, and are associated with one or more surface features such as a morphological flow or landslide, fractures, high albedo, or a pole-facing slope (one case is confirmed to be adjacent to persistent shadow). In four occurrences, these detections are associated with small (< 0.1 km2) high-albedo areas that can be recognized in high-resolution imagery (∼35 m/pixel) from the Framing Camera (FC). Since all these observations are compatible with an H2O-rich subsurface, the replenishment of surficial H2O likely comes from the ice that is present underneath. In four other occurrences, H2O is detected on walls and floors of fresh impact craters, either in the shadow or adjacent to shadows, which suggests that local thermodynamical conditions may also favor the concentration of H2O in these areas.