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Elemental mapping by Dawn reveals exogenic H in Vesta's regolith

January 1, 2012

Using Dawn’s Gamma Ray and Neutron Detector, we tested models of Vesta’s evolution based on studies of howardite, eucrite, and diogenite (HED) meteorites. Global Fe/O and Fe/Si ratios are consistent with HED compositions. Neutron measurements confirm that a thick, diogenitic lower crust is exposed in the Rheasilvia basin, which is consistent with global magmatic differentiation. Vesta’s regolith contains substantial amounts of hydrogen. The highest hydrogen concentrations coincide with older, low-albedo regions near the equator, where water ice is unstable. The young, Rheasilvia basin contains the lowest concentrations. These observations are consistent with gradual accumulation of hydrogen by infall of carbonaceous chondrites—observed as clasts in some howardites—and subsequent removal or burial of this material by large impacts.

Publication Year 2012
Title Elemental mapping by Dawn reveals exogenic H in Vesta's regolith
DOI 10.1126/science.1225354
Authors Thomas H. Prettyman, David W. Mittlefehldt, Naoyuki Yamashita, David J. Lawrence, Andrew W. Beck, William C. Feldman, Timothy J. McCoy, Harry Y. McSween, Michael J. Toplis, Timothy N. Titus, Pasquale Tricarico, Robert C. Reedy, John S. Hendricks, Olivier Forni, Lucille Le Corre, Jian-Yang Li, Hugau Mizzon, Vishnu Reddy, Carol A. Raymond, Christopher T. Russell
Publication Type Article
Publication Subtype Journal Article
Series Title Science
Index ID 70043050
Record Source USGS Publications Warehouse
USGS Organization Astrogeology Science Center