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

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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 type Article
Publication Subtype Journal Article
Title Elemental mapping by Dawn reveals exogenic H in Vesta's regolith
Series title Science
DOI 10.1126/science.1225354
Volume 338
Issue 6104
Year Published 2012
Language English
Publisher AAAS
Contributing office(s) Astrogeology Science Center
Description 5 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Science
First page 242
Last page 246
Other Geospatial Vesta
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