Challenges in detecting olivine on the surface of 4 Vesta |
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| Authors: | Andrew W Beck Timothy J McCoy Jessica M Sunshine Christina E Viviano Catherine M Corrigan Takahiro Hiroi Rhiannon G Mayne |
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| Institution: | 1. Department of Mineral Sciences, Smithsonian Institution, , Washington, District of Columbia, 20560–0112 USA;2. Department of Astronomy, University of Maryland, , College Park, Maryland, 20742–2421 USA;3. Johns Hopkins University Applied Physics Laboratory, , Laurel, Maryland, 20723 USA;4. Department of Geological Sciences, Brown University, , Providence, Rhode Island, 02912 USA;5. Department of Geology, Texas Christian University, , Fort Worth, Texas, 76129 USA |
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| Abstract: | Identifying and mapping olivine on asteroid 4 Vesta are important components to understanding differentiation on that body, which is one of the objectives of the Dawn mission. Harzburgitic diogenites are the main olivine‐bearing lithology in the howardite‐eucrite‐diogenite (HED) meteorites, a group of samples thought to originate from Vesta. Here, we examine all the Antarctic harzburgites and estimate that, on scales resolvable by Dawn, olivine abundances in putative harzburgite exposures on the surface of Vesta are likely at best in the 10–30% range, but probably lower due to impact mixing. We examine the visible/near‐infrared spectra of two harzburgitic diogenites representative of the 10–30% olivine range and demonstrate that they are spectrally indistinguishable from orthopyroxenitic diogenites, the dominant diogenitic lithology in the HED group. This suggests that the visible/near‐infrared spectrometer onboard Dawn (VIR) will be unable to resolve harzburgites from orthopyroxenites on the surface of Vesta, which may explain the current lack of identification of harzburgitic diogenite on Vesta. |
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