Detection of serpentine in exogenic carbonaceous chondrite material on Vesta from Dawn FC data

Andreas Nathues, Martin Hoffmann, Edward A. Cloutis, Michael Schäfer, Vishnu Reddy, Ulrich Christensen, Holger Sierks, Guneshwar Singh Thangjam, Lucille Le Corre, Kurt Mengel, Jean Baptist Vincent, Christopher T. Russell, Tom Prettyman, Nico Schmedemann, Thomas Kneissl, Carol Raymond, Pablo Gutierrez-Marques, Ian Hall, Irene Büttner

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The Dawn mission's Framing Camera (FC) observed Asteroid (4) Vesta in 2011 and 2012 using seven color filters and one clear filter from different orbits. In the present paper we analyze recalibrated HAMO color cubes (spatial resolution ~60. m/pixel) with a focus on dark material (DM). We present a definition of highly concentrated DM based on spectral parameters, subsequently map the DM across the Vestan surface, geologically classify DM, study its spectral properties on global and local scales, and finally, compare the FC in-flight color data with laboratory spectra.We have discovered an absorption band centered at 0.72. μm in localities of DM that show the lowest albedo values by using FC data as well as spectral information from Dawn's imaging spectrometer VIR. Such localities are contained within impact-exposed outcrops on inner crater walls and ejecta material. Comparisons between spectral FC in-flight data, and laboratory spectra of meteorites and mineral mixtures in the wavelength range 0.4-1.0. μm, revealed that the absorption band can be attributed to the mineral serpentine, which is typically present in CM chondrites. Dark material in its purest form is rare on Vesta's surface and is distributed globally in a non-uniform manner. Our findings confirm the hypothesis of an exogenic origin of the DM by the infall of carbonaceous chondritic material, likely of CM type. It further confirms the hypothesis that most of the DM was deposited by the Veneneia impact.

Original languageEnglish (US)
Pages (from-to)222-237
Number of pages16
JournalIcarus
Volume239
DOIs
StatePublished - Sep 1 2014
Externally publishedYes

Keywords

  • Asteroid vesta
  • Asteroids, composition
  • Mineralogy
  • Spectroscopy

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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