A unified CRISM VNIR/SWIR processing pipeline: Unlocking the VNIR record of Mars iron mineralogy

Observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provide critical constraints on iron-bearing mineralogy and surface aqueous processes, yet the visible-near-infrared (VNIR) dataset (400–1000 nm) remains underutilized. Here, we present an integrated, open-source denoising and spectral enhancement pipeline for CRISM VNIR and shortwave-infrared (SWIR) imagery. Although the SWIR workflow formalizes and provides the first comprehensive documentation of the processing outlined in Pan L et al. (2017), the primary methodological innovation is the newly developed extension optimized for the VNIR dataset. The workflow combines targeted despiking, automated column-wise spectral ratioing using statistically defined “bland” spectra, spatial destriping, and enhanced spectral parameter mapping. Validation at Mawrth Vallis demonstrates improved recovery of known hydrous mineral and ferric oxide signatures compared with standard processing. Application of the pipeline to Pasteur Crater and Oxia Planum, two of the candidate landing sites for China’s Tianwen-3 mission, reveals spatially coherent mineralogical signatures that are weak or ambiguous in conventional products. In Pasteur Crater, we identified widespread hydrated silica associated with light-toned layered deposits and localized hematite outcrops. At Oxia Planum, we detected widespread hematite within the Noachian clay-bearing basement that is notably absent in the overlying capping unit, suggesting that surface oxidation occurred prior to ~3.7 Ga. This pipeline enables the simultaneous mapping of ferric oxides and hydrated minerals, facilitating systematic exploitation of the CRISM VNIR archive to reconstruct paleoenvironmental redox conditions on early Mars.