NOAO >   Observing Info >   Approved Programs >   2016B-0295

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Program Information for 2016B-0295


PI: Cristina A Thomas, NASA Goddard Space Flight Center, cristina.a.thomas@nasa.gov
Address: Code 691, 8800 Greenbelt Rd., Greenbelt, MD 20771 USA

CoI: Lucy F Lim, NASA Goddard Space Flight Center
CoI: David Trilling, Northern Arizona U.
CoI: Nicholas Moskovitz, Lowell Observatory

Title: Search for a Differentiated Asteroid Family

Abstract: Dynamical asteroid families resulting from catastrophic disruptions represent the interiors of their former parent bodies. Differentiation of a large initially chondritic parent body is expected to produce an ``onion shell" object with a metal core, a thick olivine-rich mantle, and a thin basaltic crust. However, instead of the mineralogical diversity expected from the disruption of a differentiated parent body, most asteroid families tend to show similar spectra among the members. Moreover, spectra of metal-like materials and olivine-dominated assemblages have not been detected in asteroid families in the Main Belt and the expected mantle material is missing from the meteorite record. The deficit of olivine-rich mantle material in the meteorite record and in asteroid observations is known as the ``Missing Mantle" problem. For years the best explanation for the lack of mantle material has been the ``battered to bits" hypothesis that states that all differentiated parent bodies (aside from Vesta) were disrupted very early in the solar system and the resulting olivine-rich material was collisionally broken down until the object diameters fell below our observational limits. However, in a competing hypothesis, Elkins-Tanton et al. (2013) has suggested that previous work has overestimated the amount of olivine produced by the differentiation of a chondritic parent body. We propose to obtain visible spectra of asteroids within the Massalia, Merxia, and Agnia S-type families to search for compositional variations that are indicators of differentiation and to quantitatively constrain the two competing ``Missing Mantle" hypotheses.

Program Type: Standard/Solar System

Scheduled Nights:
Run 1 (2016B):  SOAR/Goodman -- 2n on Oct 15 - Oct 16 2016


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