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Dalle Ore CM, Long CJ, Nichols-Fleming F, Scipioni F, Rivera Valentín EG, Lopez Oquendo AJ, Cruikshank DP. Dione's Wispy Terrain: A Cryovolcanic Story? THE PLANETARY SCIENCE JOURNAL 2021; 2:83. [PMID: 35005622 PMCID: PMC8740528 DOI: 10.3847/psj/abe7ec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We examine the H2O ice phase on the surface of Dione, one of Saturn's icy satellites, to investigate whether it might harbor cryovolcanic activity induced by a subcrustal body of water. Several studies have searched for such a signature, as summarized in Buratti et al.; however, none has yet produced sufficient evidence to dissipate doubts. In the radiation environment characteristic of Saturn's icy moons, the presence of crystalline H2O ice has been used as a marker of a high-temperature region. Because ion bombardment will, over time, drive crystalline ice toward an increasingly amorphous state, the current phase of the H2O ice can be used to gauge the temporal temperature evolution of the surface. We adopt a technique described by Dalle Ore et al. to map the fraction of amorphous to crystalline H2O ice on Dione's surface, observed by the Cassini Visible and Infrared Mapping Spectrometer, and provide an ice exposure age. We focus on a region observed at high spatial resolution and centered on one of the faults of the Wispy Terrain, which is measured to be fully crystalline. By assuming an amorphous to crystalline ice fraction of 5% (i.e., 95% crystallinity), significantly higher than the actual measurement, we obtain an upper limit for the age of the fault of 152 Ma. This implies that the studied fault has been active in the last ~100 Ma, supporting the hypothesis that Dione might still be active or was active a very short time ago, and similarly to Enceladus, might still be harboring a body of liquid water under its crust.
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Affiliation(s)
- Cristina M Dalle Ore
- SETI Institute, 183 Bernardo Avenue, Ste 200, Mountain View, CA 94043, USA
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | | | - Fiona Nichols-Fleming
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, RI 02912, USA
| | - Francesca Scipioni
- SETI Institute, 183 Bernardo Avenue, Ste 200, Mountain View, CA 94043, USA
| | - Edgard G Rivera Valentín
- Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Boulevard, Houston, TX 77058, USA
| | - Andy J Lopez Oquendo
- Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Boulevard, Houston, TX 77058, USA
- Department of Astronomy and Planetary Science, Northern Arizona University, 527 S. Beaver Street, Flagstaff, AZ 86011, USA
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Materese CK, Cruikshank DP, Sandford SA, Imanaka H, Nuevo M. ICE CHEMISTRY ON OUTER SOLAR SYSTEM BODIES: ELECTRON RADIOLYSIS OF N 2-, CH 4-, AND CO-CONTAINING ICES. THE ASTROPHYSICAL JOURNAL 2015; 812:10.1088/0004-637X/812/2/150. [PMID: 32020918 PMCID: PMC6999742 DOI: 10.1088/0004-637x/812/2/150] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radiation processing of the surface ices of outer Solar System bodies may be an important process for the production of complex chemical species. The refractory materials resulting from radiation processing of known ices are thought to impart to them a red or brown color, as perceived in the visible spectral region. In this work, we analyzed the refractory materials produced from the 1.2-keV electron bombardment of low-temperature N2-, CH4-, and CO-containing ices (100:1:1), which simulates the radiation from the secondary electrons produced by cosmic ray bombardment of the surface ices of Pluto. Despite starting with extremely simple ices dominated by N2, electron irradiation processing results in the production of refractory material with complex oxygen- and nitrogen-bearing organic molecules. These refractory materials were studied at room temperature using multiple analytical techniques including Fourier-transform infrared spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). Infrared spectra of the refractory material suggest the presence of alcohols, carboxylic acids, ketones, aldehydes, amines, and nitriles. XANES spectra of the material indicate the presence of carboxyl groups, amides, urea, and nitriles, and are thus consistent with the IR data. Atomic abundance ratios for the bulk composition of these residues from XANES analysis show that the organic residues are extremely N-rich, having ratios of N/C ~ 0.9 and O/C ~ 0.2. Finally, GC-MS data reveal that the residues contain urea as well as numerous carboxylic acids, some of which are of interest for prebiotic and biological chemistries.
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Affiliation(s)
- Christopher K Materese
- NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
- Oak Ridge Associated Universities, P.O. Box 117, MS 36, Oak Ridge, TN 37831-0117, USA
| | - Dale P Cruikshank
- NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
| | - Scott A Sandford
- NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
| | - Hiroshi Imanaka
- NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
- SETI Institute, 189 N. Bernardo Ave., Suite 100, Mountain View, CA 94043, USA
| | - Michel Nuevo
- NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
- Bay Area Environmental Research Institute, 625 2nd St., Suite 209, Petaluma, CA 94952, USA
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Bennett CJ, Pirim C, Orlando TM. Space-Weathering of Solar System Bodies: A Laboratory Perspective. Chem Rev 2013; 113:9086-150. [DOI: 10.1021/cr400153k] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chris J. Bennett
- Department of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States
| | - Claire Pirim
- Department of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States
| | - Thomas M. Orlando
- Department of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States
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