Near-Infrared Spectroscopy of Warm Spitzer-observed Near-Earth Objects

We have completed a spectroscopic observing campaign to complement the ExploreNEOs Warm Spitzer program. ExploreNEOs or “The Warm Spitzer NEO Survey: Exploring the history of the inner Solar System and near-Earth space” was allocated 500 hours over two years (2009-2011) to determine diameters and albedos for approximately 600 near-Earth objects using the 3.6 and 4.5 micron IRAC bands. We present the results of the SpeX component of our campaign. In order to increase our sample size we also include all near-infrared observations of ExploreNEOs targets in the MIT-UH-IRTF Joint Campaign for Spectral Reconnaissance. Our complete dataset includes 125 observations of 92 objects from our survey and 213 observations of 154 objects from the MIT survey. The combination of the two surveys includes near-infrared spectroscopy of 187 ExploreNEOs targets. We find no correlation between spectral band parameters and ExploreNEOs albedos and diameters. We identified all potential ordinary chondrites within our sample and determined likely ordinary chondrite types using the equations derived by Dunn et al. 2010. Our resulting proportions of H, L, and LL ordinary chondrites are different than those previously calculated for ordinary chondrite-like near-Earth objects and meteorite falls.