Replenishment of Near-Surface Water Ice by Impacts Into Ceres' Volatile-Rich Crust: Observations by Dawn's Gamma Ray and Neutron Detector

被引：2

作者：

Prettyman, T. H. ^{[1
]}

Yamashita, N. ^{[1
]}

Landis, M. E. ^{[2
]}

Castillo-Rogez, J. C. ^{[3
]}

Schorghofer, N. ^{[1
]}

Pieters, C. M. ^{[1
,4
]}

Sizemore, H. G. ^{[1
]}

Hiesinger, H. ^{[5
]}

Marchi, S. ^{[6
]}

McSween, H. Y. ^{[7
]}

Park, R. S. ^{[3
]}

Toplis, M. J. ^{[8
]}

Raymond, C. A. ^{[3
]}

Russell, C. T. ^{[9
]}

机构：

[1] Planetary Sci Inst, Tucson, AZ 85719 USA

[2] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA

[3] CALTECH, Jet Prop Lab, Pasadena, CA USA

[4] Brown Univ, Providence, RI 02912 USA

[5] Westfalische Wilhelms Univ Munster, Inst Planetol, Munster, Germany

[6] Southwest Res Inst, Boulder, CO USA

[7] Univ Tennessee, Knoxville, TN USA

[8] Univ Toulouse, Inst Rech Astrophys & Planetol, UT3, CNRS, Toulouse, France

[9] Univ Calif Los Angeles, Los Angeles, CA USA

来源：

GEOPHYSICAL RESEARCH LETTERS | 2021年 / 48卷 / 15期

关键词：

Ceres; ice stability; impacts; regolith; crust; Nuclear Spectroscopy; EVOLUTION; TEMPERATURE; MODEL; SHAPE;

D O I：

10.1029/2021GL094223

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Ceres' regolith contains water ice that has receded in response to insolation-driven sublimation. Specially targeted, high spatial-resolution measurements of hydrogen by Dawn's Gamma Ray and Neutron Detector (GRaND) reveal elevated hydrogen concentrations in and around Occator, a young, 90 km diameter, complex crater located at 19.82 degrees N where near-surface ice is not expected. The excess hydrogen can be explained by impact excavation of water-rich outer crustal materials and their emplacement in the crater floor and ejecta blanket. This is supported by thermophysical models that show water ice could survive at sub-meter depths, given Occator's relatively young age (similar to 20 Myr). We hypothesize that the regolith can be replenished with ice from large impacts and that this process partially controls the distribution and depth of near surface ice. This is supported by results from Occator and similarities in the global distribution of hydrogen and the pattern of large craters (20-100 km diameter).

引用

页数：10

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