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R. P. Binzel, S. J. Bus (MIT), T. H. Burbine (NMNH), J. S. Stuart (MIT)
Through the use of telescope facilities at Palomar, Kitt Peak, NASA IRTF, and Keck, we have accumulated a data set of visible and near-infrared spectroscopic properties for 200 near-Earth objects (NEOs). Most NEOs observed are in the size range of 2 km or less, with the smallest spectroscopically measured object having a size of about 15m. One-third of our sampled objects fall in the Sq and Q classes and resemble ordinary chondrite meteorites, demonstrating that analogs for the most common meteorite are relatively common in near-Earth space. Our sample also verifies (Binzel et al. 1996, Science 273, 946) a clear transition between S-type and Q-type compositional classes over visible and near-infrared wavelengths. We will further report on the results of a comparative analysis between these physical measurements of NEOs and identical measurements for more than 1000 main-belt asteroids. We seek to identify the range of spectral diversity between near-Earth and main-belt objects. Uncovering size-dependent spectral properties may have implications for surface alteration processes that may be responsible for difficulties in making conclusive asteroid-meteorite connections. We also seek to uncover any possible trends in orbital dependences that may help to reveal NEO origins from asteroid or cometary populations.
This work was supported by NASA Grant NAG5-3939 and NSF Grant AST-9530282.