COMPOSITIONAL VARIATIONS ON THE MOON - RECALIBRATION OF GALILEO SOLID-STATE IMAGING DATA FOR THE ORIENTALE REGION AND FARSIDE

Updated radiometric calibration and systematic processing procedures f or Galileo solid-state imaging (SSI) data from the first(1990) Earth-M oon encounter are presented. These procedures were applied to a whole- disk imaging sequence of the Moon centered near Mare Orientale, called Lunmap 14 (L14). Processing of L14 data included radiometric calibrat ion, subpixel coregistration, scattered light removal, geometric contr ol and reprojection, photometric normalization, and calibration to Ear th-based spectra. Coregistration and scattered-light removal procedure s are improvements over the initial calibration of the SSI mosaics. Th e effects of scattered light correction are best seen using a whole-Mo on view such as L14; resolution of the debated amounts of light scatte ring from within or outside the camera field of view is not necessary. Scattered light removal particularly affects the 1-mu m spectral regi on and has implications for interpretation of mafic mineral signatures in mare deposits of the lunar limb and farside. Recalibrated spectra indicate that mare ponds of the limb show moderately deep 1-mu m absor ptions, and thus mafic mineral contents, comparable to those of other nearside basalts. Mafic mineral contents of Schiller-Shickard cryptoma ria are higher than previously thought and are similar to some low-Ti nearside basalts. Many of the recalibrated spectra from South Pole/Ait ken are similar to those of Schiller-Schickard cryptomaria, suggesting that many of these soils represent a mixed mare/highland lithology, T he hypothesis that there is an olivine enrichment in southern South Po le/Aitken basin is not supported strongly by spectra shown here.