Olivine-Pyroxene Distribution of S-type Asteroids Throughout the Main Belt

The mineralogical composition of asteroids can be constrained using visible and near-IR (VNIR) spectroscopy. The most prominent spectral features observed over this wavelength range are due to olivine and pyroxene, the two most abundant minerals in both chondritic and achondritic meteorites. The observed ratio of these two minerals is highly dependent on the amount of heating that an asteroid has undergone. The 1-micron band minimum and the band area ratio (BAR) between the 2and 1-micron bands reveal the relative abundance of olivine and/or pyroxene on an asteroid surface (Gaffey 1993). A large sample of S-, A-, V-, and R-type asteroid spectra was collected over the visible and near-IR wavelengths. Here we present a methodology for calculating the location of the 1-micron band minimum and BAR with appropriate 1sigma uncertainties. This method was used to characterize approximately 200 S-type asteroids throughout the main belt. We will also present the distribution of olivine / pyroxene throughout the main belt by measuring how the S-type mineralogy varies with heliocentric distance. This will provide a better understanding of both the thermal processing across the main belt and subsequent mixing of asteroids through collisional and dynamical processes.