A first look at CRISM hyperspectral mapping mosaicked data: Results from Mawrth Vallis

The CRISM instrument on MRO collected visible-infrared hyperspectral mapping data (HSP; 180 m/pixel, 262 spectral channels covering 365 to 3937 nm) that covered ∼39% of Mars. Here we present results from a new processing pipeline for these data that produces 5° x 5° hyperspectral mapping tiled mosaics that overlap the coverage of recently released multispectral map tile products (version 4 Multispectral Reduced Data Records, MRDRs; 180 m/pixel, 72 spectral channels). These data enable regional investigations into compositional variations that require high spectral resolution or wavelengths not included in MRDRs. In addition to standard processing techniques available in the CRISM Analysis Toolkit (CAT), the pipeline includes a new correction for systematic discrepancies in radiometric calibration between CRISM observing modes, an improved filtering algorithm to remediate noise, and a technique to correct for differences in radiometry among data strips that arise from differences in photometric and atmospheric conditions. Demonstration hyperspectral mapping tiles covering the Mawrth Vallis region were developed and compared with MRDRs and high spatial resolution hyperspectral targeted observations. The new processing pipeline shows an improvement in data quality over standard processing using CAT utilities. Compared to targeted observations (18 or 36 m/pixel, 545 spectral channels), hyperspectral mapping tile mosaics reveal compositional information across a much greater spatial extent at the expense of 5–10 times coarser spatial resolution. In addition, the hyperspectral mapping tile mosaics reveal greater compositional detail in both the spatial and spectral dimensions compared to MRDRs, but with sparser spatial coverage. Sample hyperspectral mapping tile mosaics over the Mawrth Vallis region reveal hydrated silica, Al-bearing smectite, Fe/Mg-bearing smectite, and mixed clays, consistent with compositions previously reported in the literature.