Compositional variability on the surface of 4 Vesta revealed through GRaND measurements of high-energy gamma rays

Patrick N. Peplowski, David J. Lawrence, Thomas H. Prettyman, Naoyuki Yamashita, Dave Bazell, William C. Feldman, Lucille Le Corre, Timothy J. McCoy, Vishnu Reddy, Robert C. Reedy, Chris T. Russell, Michael J. Toplis

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Measurements of the high-energy gamma-ray flux emanating from asteroid 4 Vesta by the Dawn Gamma-Ray and Neutron Detector (GRaND) have revealed variability in the near-surface elemental composition of the Vestan surface. These observations are consistent with the presence of large (≥8 × 104 km2) regions with distinct, HED-like elemental compositions. The results agree broadly with other global measurements, such as the macroscopic neutron absorption cross section and spectral reflectance-derived mineralogic maps. Two distinct regions with eucrite-like elemental compositions have been identified, the first located primarily within the Lucaria and Marcia quadrangles and the second within Oppia quadrangle. The former region is collocated with some of the oldest, most heavily cratered terrain on Vesta. The interior of the 500 km diameter Rheasilvia impact basin is found to have a composition that is consistent with diogenite-like material. Taken together, these observations support the hypothesis that Vesta's original crust was composed of basaltic outflows in the form of eucritic-like material and that the Rheasilvia-basin-forming impact exposed lower-crustal, diogenite-like material. These measurements also constrain the maximum amount of mesosiderite-like material to <10% for each 15 × 15° surface element.

Original languageEnglish (US)
Pages (from-to)2252-2270
Number of pages19
JournalMeteoritics and Planetary Science
Volume48
Issue number11
DOIs
StatePublished - Nov 2013
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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