DPS 35th Meeting, 1-6 September 2003
Session 34. Asteroid Physical Studies III
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[34.12] Mineralogical Analyses of Two Small Vesta Family Asteroids

M. S. Kelley (Georgia Southern University), F. Vilas (NASA Johnson Space Center), M. J. Gaffey (University of North Dakota), A. Hicks (Georgia Southern University), P. A. Abell (Rensselaer Polytechnic Institute), S. M. Lederer (California State University at San Bernardino)

Asteroid 4 Vesta is a target of the Dawn Mission under NASA's Discovery program. Experience gained from the NEAR mission demonstrates that a firm understanding of an asteroid's geology prior to the mission permits more sophisticated questions to be addressed during the mission. Our recent work (Kelley et al. 2003, Icarus, in press) shows that much can be learned about Vesta by studying genetically related asteroids in the Vesta region of the main belt.

The depth, width, and spectral placement of the 1- and 2-micron mafic silicate absorption features in the reflectance spectrum of 4 Vesta (the archetype V-class asteroid) indicate that orthopyroxene is a major phase in its surface mineralogy. Hubble Space Telescope observations confirmed albedo differences across Vesta's surface, and produced shape and topographic information about Vesta. Dynamical studies previously revealed that a family of mainbelt asteroids is associated with Vesta. Taxonomic surveys have found numerous, smaller asteroids with Vesta-like 1-micron spectral absorption features.

Until recently, work on the surface mineralogy of Vesta was the definitive analysis for V-class asteroids since no complete near-infrared spectrum of another V-type had been quantified. The case for a Vesta-HED meteorite connection has a firm mineralogical foundation. Previous spectral data have suggested a link to additional V-class asteroids, but until now that supposed association had not been mineralogically tested.

Analyses of our near-infrared reflectance spectra for asteroids 1929 Kollaa and 3494 Purple Mountain, which include the critical 1- and 2-micron spectral absorption features, allowed us not only to determine that these mainbelt asteroids are daughters of 4 Vesta, but also to constrain the location of their formation within Vesta and establish their connection to the cumulate eucrites. This is the first mineralogical link to be made between the HED meteorites and an asteroid other than Vesta, and between Vesta and another asteroid.

The author(s) of this abstract have provided an email address for comments about the abstract: mkelley@gasou.edu

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.