Small main-belt asteroid spectroscopic survey in the near-infrared

Near-infrared spectra (similar to0.90 to similar to1.65 mum) are presented for 181 main-belt asteroids, more than half having diameters less than 20 km. These spectra were measured using a specialized grism at the NASA Infrared Telescope Facility, where the near-infrared wavelength coverage is designed to complement visible wavelength CCD measurements for enhanced mineralogic interpretation. We have focused our analysis on asteroids that appear to have surfaces dominated by olivine or pyroxene since these objects can be best characterized with spectral coverage only out to 1.65 mum. Olivine-dominated A-type asteroids have distinctly redder slopes than olivine found in meteorites, possibly due to surface alteration effects such as micro-meteoroid bombardment simulated by laser irradiation laboratory experiments. K-type asteroids observed within the Eos family tend to be well matched by laboratory spectra of CO3 chondrites, while those independent of the Eos family have a variety of spectral properties. The revealed structure of the 1-mum band for 3628 Boznemcova appears to refute its previously proposed match to ordinary chondrite meteorites. Boznemcova displays a 1-mum band that is unlike that for any currently measured meteorite; however, spectra out to 2.5 mum are needed to conclusively argue that Boznemcova has a surface mineralogy different from that of ordinary chondrites. Extending the spectral coverage of Vestoids out to similar to1.65 mum continues to be consistent with the "genetic" relationship of almost all observed Vestoids with Vesta and the howardites, eucrites, and diogenites. Eucrites/howardites provide the best spectral matches to the observed Vestoids. (C) 2002 Elsevier Science (USA).