Remote sensing and geologic studies of the Schiller-Schickard region of the Moon

Near-infrared reflectance spectra, multspectral images, and photogeologic data for the Schiller-Schickard (SS) region were obtained and analyzed in order to determine the composition and origin of a variety of geologic units. Thes include light plains deposits, Orientale-related deposits, mare units, and dark-haloed impact craters (DHCs). Spectral data indicate that the pre-Orientale highland surface was dominated by noritic anorthosite. Near-IR spectra show that DHCs in the region have excavated ancient (>3.8 Ga) mare basalts from beneath highland-bearing material emplaced by the Orientale impact. Acient mare basalts were widespread in the SS region prior to the Orientale event, and their distribution appears to have been controlled by the presence of several old impact basins,including the Schiller-Zucchius basin and a basin previously unrecognized. Both Near-IR spectra and multispectral images indicate that light plains and other Orientale-related units in the SS region contain major amounts of local pre-Orientale mare basalt. The amountsof local material in these deposits approach, but seldom exceed, the maximum values predicted by the local mixing hypothesis of Oberbeck and co-workers

Spectral and Multispectral Imaging Studies of Lunar Mantled Mare Deposits

Near-IR reflectance spectra (0.6-2.5 m) and CCD images in the extended visible range (0.4-1.0 m) obtained wth earth-based teles- copes have been used to investigate the composition and origin of formations in the Schiller-Schickard region of the Moon. Of particular interest are the Schickard light plains, which represent an area of mantled mare basalt, or crypto,are. Here local pre- existing mare basalts were eroded and incorporated into a highlands- rich deposit by ejecta from the Orientale Basin. Spectral observa- tions of mature and inmature highland and mare surfaces, as well as dark-halo crater materials provide information on the mafic mineralogy of features in the area. Analyses of the "1 m" absorptionband and spectral mixing models indicate that selected spots in the light plains contain on the order of 50% mare basalt. CCD image cubescan be used to map the amount of basalt in the light plains and evaluate changes with radial distance from Orientale

Remote Sensing Studies of the Northeastern Portion of the Lunar Nearside

During the Galileo spacecraft enounter with the Earth-Moon system in December, 1992, a variety of spectral data and imagery were obtained for the eastern limb regon as well as much of the lunar nearside. In order to support this encounter, we have been collecting near-infra- red spectra and other remote sensing data for that portion of the northeastern nearside (NEN region) for which the highest resolution Galileo data were obtained. Analysis of spectra obtained for high- lands units in the NEN region indicates that most surface units are dominated by anorthositic norite. To date, no pure anorthosites have been identified in the region. Several dark-haloed impact craters have exposed mare material from beneath highlands-rich surface units.Hence, ancient mare volcanism occured in at least a portion of the NEN region. Endogenic dark-haloed craters in the region are the sources of localized dark mantle deposits (LDMD) of pyroclastic origin and at least two compositional groups are present