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Mineralogical Analysis of the Oppia Quadrangle of Asteroid (4) Vesta: Evidence for Occurrence of Moderate-Reflectance Hydrated MineralsQuadrangle Av-10 'Oppia' is one of five quadrangles that cover the equatorial region of asteroid (4) Vesta. This quadrangle is notable for the broad, spectrally distinct ejecta that extend south of the Oppia crater. These ejecta exhibit the steepest ('reddest') visible spectral slope observed across the asteroid and have distinct color properties as seen in multispectral composite images. Compared to previous works that focused on the composition and nature of unusual ('orange') ejecta found on Vesta, here we take into account a broader area that includes several features of interest, with an emphasis on mineralogy as inferred from data obtained by Dawn's Visible InfraRed mapping spectrometer (VIR). Our analysis shows that the older northern and northeastern part of Av-10 is dominated by howardite-like material, while the younger southwestern part, including Oppia and its ejecta blanket, has a markedly eucritic mineralogy. The association of the mineralogical information with the geologic and topographic contexts allows for the establishment of relationships between the age of the main formations observed in this quadrangle and their composition. A major point of interest in the Oppia quadrangle is the spectral signature of hydrous material seen at the local scale. This material can be mapped by using high-resolution VIR data, combined with multispectral image products from the Dawn Framing Camera (FC) so as to enable a clear correlation with specific geologic features. Hydrated mineral phases studied previously on Vesta generally correlate with low-albedo material delivered by carbonaceous asteroids. However, our analysis shows that the strongest OH signature in Av-10 is found in a unit west of Oppia, previously mapped as 'light mantle material' and showing moderate reflectance and a red visible slope. With the available data we cannot yet assess the presence of water in this material. However, we offer a possible explanation for its origin.
Document ID
20150023283
Document Type
Reprint (Version printed in journal)
Authors
Tosi, F. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
Frigeri, A. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
Combe, J.-Ph. (Bear Fight Inst., Inc. Winthrop, WA, United States)
Zambon, F. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
De Sanctis, M. C. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
Ammannito, E. (California Univ. Los Angeles, CA, United States)
Longobardo, A. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
Hoffmann, M. (Max-Planck Inst. for Solar System Research Germany)
Nathues, A. (Max-Planck Inst. for Solar System Research Germany)
Garry, W. B. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Blewett, D. T. (Johns Hopkins Univ. Laurel, MD, United States)
Pieters, C. M. (Brown Univ. Providence, RI, United States)
Palomba, E. (Istituto di Astrofisica e Planetologia Spaziale (INAF-IAPS) Rome, Italy)
Stephan, K. (Deutsches Zentrum fuer Luft- und Raumfahrt e.V. Berlin, Germany)
McFadden, L. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
McSween, H. Y. (Tennessee Univ. Knoxville, TN, United States)
Russell, C. T. (California Univ. Los Angeles, CA, United States)
Raymond, C. A. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
December 18, 2015
Publication Date
May 21, 2015
Publication Information
Publication: Icarus
Volume: 259
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
GSFC-E-DAA-TN27430
Funding Number(s)
CONTRACT_GRANT: ASI-INAF I/004/12/0
Distribution Limits
Public
Copyright
Other
Keywords
Asteroids
Spectrophotometry
Asteroid Vesta
surfaces