Composition of Near-Earth Asteroid 2008 EV5: Potential target for Robotic and Human Exploration

摘要

We observed potentially hazardous asteroid (PHA) 2008 EV5 in the visible(0.30-0.92 microns) and near-IR (0.75-2.5 microns) wavelengths to determine itssurface composition. This asteroid is especially interesting because it is apotential target for two sample return mission proposals (Marco Polo-R andHayabusa-2) and human exploration due to its low delta-v for rendezvous. Thespectrum of 2008 EV5 is essentially featureless with exception of a weak0.48-microns spin-forbidden Fe3+ absorption band. The spectrum also has anoverall blue slope. The albedo of 2008 EV5 remains uncertain with a lower limitat 0.05 and a higher end at 0.20 based on thermal modeling. The Busch et al.(2011) albedo estimate of 0.12 is consistent with our thermal modeling results.The albedo and composition of 2008 EV5 are also consistent with a C-typetaxonomic classification (Somers et al. 2008). The best spectral match is withCI carbonaceous chondrites similar to Orgueil, which also have a weak0.48-microns feature and an overall blue slope. This 0.48-microns feature isalso seen in the spectrum of magnetite. The albedo of CI chondrites is at thelower limit of our estimated range for the albedo of 2008 EV5.