Feierberg, Michael Andrew EVIDENCE FOR A COMPOSITIONAL RELATIONSHIP BETWEEN ASTEROIDS AND METEORITES FROM INFRARED SPECTRAL REFLECTANCES

High-resolution Fourier spectra in the 0.9-2.5 ym region were measured for sixteen asteroids. These data were combined with 0.3-1.1 um spectrophotometry and 3.0-3.5 urn narrowband photometry for compositional analysis. Comparison spectra of meteorites and terrestrial minerals were measured in the laboratory, some under simulated asteroidal conditions of pressure and temperature. Spectra of eleven representative S-type asteroids show a range of olivine/pyroxene ratios overlapping those of ordinary and carbonaceous chondrites, but not approaching those of common differentiated meteorite types. The reddening in the asteroid spectra implies the presence of metallic iron, but if the metal is finely divided its abundance could be low. S-type asteroids have spectra most consistent with undifferentiated compositions, and some of them, especially 8 Flora, could be ordinary chondrite parent bodies. 4 Vesta and 349 Dembowska are unusual asteroids which have spectra resembling those of achondritic meteorites. Vesta has a pyroxene-feldspar mineralogy intermediate in composition between eucrites and howardites. If shergottite-like basalts are present, they must be in low abundance. Dembowska has an olivine-pyroxene mineralogy similar in some ways to ordinary chondrites, but there is considerable