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 for Galileo solid-state imaging (SSI) data from the first(1990) Earth-Moon 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 calibration, subpixel coregistration, scattered light removal, geometric control and reprojection, photometric normalization, and calibration to Earth-based spectra. Coregistration and scattered-light removal procedures are improvements over the initial calibration of the SSI mosaics. The effects of scattered light correction are best seen using a whole-Moon view such as L14; resolution of the debated amounts of light scattering from within or outside the camera field of view is not necessary. Scattered light removal particularly affects the 1-mu m spectral region 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 absorptions, and thus mafic mineral contents, comparable to those of other nearside basalts. Mafic mineral contents of Schiller-Shickard cryptomaria are higher than previously thought and are similar to some low-Ti nearside basalts. Many of the recalibrated spectra from South Pole/Aitken are similar to those of Schiller-Schickard cryptomaria, suggesting that many of these soils represent a mixed mare/highland lithology, The hypothesis that there is an olivine enrichment in southern South Pole/Aitken basin is not supported strongly by spectra shown here.