David J. Lawrence^1,*, Patrick N. Peplowski¹, Thomas H. Prettyman², William C. Feldman², David Bazell¹, David W. Mittlefehldt³, Robert C. Reedy², Naoyuki Yamashita²

¹The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
²Planetary Science Institute, Tucson, Arizona, USA
³NASA Johnson Space Center, Houston, Texas, USA

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These data provide additional compositional evidence that Vesta is the parent body to HED meteorites. A subset of fast neutron data having lower statistical precision show spatial variations that are consistent with a 400 ppm variability in hydrogen concentrations across Vesta and supports the idea that Vesta’s hydrogen is due to long-term delivery of carbonaceous chondrite material.

Reference
Lawrence DJ, Peplowski PN, Prettyman TH, Feldman W, Bazell D, Mittlefehldt DW, Reedy RC and Yamashita N (in press) Constraints on Vesta’s elemental composition: Fast neutron measurements by Dawn’s gamma ray and neutron detector. Meteoritics & Planetary Science
[doi:10.1111/maps.12187]
Published by arrangement with John Wiley & Sons

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