Detection of local H2O exposed at the surface of Ceres.

Authors :: Combe JP
McCord TB
Tosi F
Ammannito E
Carrozzo FG
De Sanctis MC
Raponi A
Byrne S
Landis ME
Hughson KH
Raymond CA
Russell CT
Source :: Science (New York, N.Y.) [Science] 2016 Sep 02; Vol. 353 (6303). Date of Electronic Publication: 2016 Sep 01.
Publication Year :: 2016
Abstract: The surface of dwarf planet Ceres contains hydroxyl-rich materials. Theories predict a water ice-rich mantle, and water vapor emissions have been observed, yet no water (H <subscript>2</subscript> O) has been previously identified. The Visible and InfraRed (VIR) mapping spectrometer onboard the Dawn spacecraft has now detected water absorption features within a low-illumination, highly reflective zone in Oxo, a 10-kilometer, geologically fresh crater, on five occasions over a period of 1 month. Candidate materials are H <subscript>2</subscript> O ice and mineral hydrates. Exposed H <subscript>2</subscript> O ice would become optically undetectable within tens of years under current Ceres temperatures; consequently, only a relatively recent exposure or formation of H <subscript>2</subscript> O would explain Dawn's findings. Some mineral hydrates are stable on geological time scales, but their formation would imply extended contact with ice or liquid H <subscript>2</subscript> O.<br /> (Copyright © 2016, American Association for the Advancement of Science.)