Vesta's mineralogical composition as revealed by the visible and infrared spectrometer on Dawn |
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| Authors: | M Cristina De Sanctis Eleonora Ammannito M Teresa Capria Fabrizio Capaccioni Jean‐Philippe Combe Alessandro Frigeri Andrea Longobardo Gianfranco Magni Simone Marchi Tom B McCord Ernesto Palomba Federico Tosi Francesca Zambon Francesco Carraro Sergio Fonte Y J Li Lucy A McFadden David W Mittlefehldt Carle M Pieters Ralf Jaumann Katrin Stephan Carol A Raymond Christopher T Russell |
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| Institution: | 1. Istituto di Astrofisica e Planetologia Spaziali, INAF, , Rome, Italy;2. Bear Fight Institute, , Winthrop, Washington, 98862 USA;3. NASA Lunar Science Institute, , Boulder, Colorado, USA;4. Planetary Science Institute, , Tucson, Arizona, 85719, USA;5. NASA, Goddard Space Flight Center, , Greenbelt, Maryland, 20771 USA;6. Astromaterials Research Office, NASA Johnson Space Center, , Houston, Texas, 77058 USA;7. Brown University, , Providence, Rhode Island, 02912 USA;8. Institute of Planetary Research, DLR, , Berlin, 80302 Germany;9. Jet Propulsion Laboratory, , Pasadena, California, 91109 USA;10. Institute of Geophysics and Planetary Physics, University of California, , Los Angeles, California, 90095–1567 USA |
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| Abstract: | The Dawn spacecraft mission has provided extensive new and detailed data on Vesta that confirm and strengthen the Vesta–howardite–eucrite–diogenite (HED) meteorite link and the concept that Vesta is differentiated, as derived from earlier telescopic observations. Here, we present results derived by newly calibrated spectra of Vesta. The comparison between data from the Dawn imaging spectrometer—VIR—and the different class of HED meteorites shows that average spectrum of Vesta resembles howardite spectra. Nevertheless, the Vesta spectra at high spatial resolution reveal variations in the distribution of HED‐like mineralogies on the asteroid. The data have been used to derive HED distribution on Vesta, reported in Ammannito et al. (2013), and to compute the average Vestan spectra of the different HED lithologies, reported here. The spectra indicate that, not only are all the different HED lithologies present on Vesta, but also carbonaceous chondritic material, which constitutes the most abundant inclusion type found in howardites, is widespread. However, the hydration feature used to identify carbonaceous chondrite material varies significantly on Vesta, revealing different band shapes. The characteristic of these hydration features cannot be explained solely by infalling of carbonaceous chondrite meteorites and other possible origins must be considered. The relative proportion of HEDs on Vesta's surface is computed, and results show that most of the vestan surface is compatible with eucrite‐rich howardites and/or cumulate or polymict eucrites. A very small percentage of surface is covered by diogenite, and basaltic eucrite terrains are relatively few compared with the abundance of basaltic eucrites in the HED suite. The largest abundance of diogenitic material is found in the Rheasilvia region, a deep basin, where it clearly occurs below a basaltic upper crust. However, diogenite is also found elsewhere; although the depth to diogenite is consistent with one magma ocean model, its lateral extent is not well constrained. |
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