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Prettyman TH, Yamashita N, Toplis MJ, McSween HY, Schörghofer N, Marchi S, Feldman WC, Castillo-Rogez J, Forni O, Lawrence DJ, Ammannito E, Ehlmann BL, Sizemore HG, Joy SP, Polanskey CA, Rayman MD, Raymond CA, Russell CT. Extensive water ice within Ceres' aqueously altered regolith: Evidence from nuclear spectroscopy. Science 2016; 355:55-59. [PMID: 27980087 DOI: 10.1126/science.aah6765] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/23/2016] [Indexed: 11/03/2022]
Abstract
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.
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Affiliation(s)
- T H Prettyman
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA.
| | - N Yamashita
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA
| | - M J Toplis
- Institut de Recherche d'Astrophysique et Planétologie, CNRS, Université Paul Sabatier, Toulouse 31400, France
| | - H Y McSween
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410, USA
| | - N Schörghofer
- University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
| | - S Marchi
- Southwest Research Institute, Boulder, CO 80302, USA
| | - W C Feldman
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA
| | - J Castillo-Rogez
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - O Forni
- Institut de Recherche d'Astrophysique et Planétologie, CNRS, Université Paul Sabatier, Toulouse 31400, France
| | - D J Lawrence
- Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723, USA
| | - E Ammannito
- Earth Planetary and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1567, USA
| | - B L Ehlmann
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109-8099, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - H G Sizemore
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA
| | - S P Joy
- Earth Planetary and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1567, USA
| | - C A Polanskey
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - M D Rayman
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - C A Raymond
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - C T Russell
- Earth Planetary and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1567, USA
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