Achieving higher-resolution visible/near-infrared hyperspectral surface composition on Mars through cross-instrument CRISM-CaSSIS pansharpening

Spectrometry is one of the main tools used in planetary mineralogical characterisation, especially on Mars, driven by past and current missions. Despite recent technical advances, physical limitations restrict the spatial resolution capability of hyperspectral sensors in orbit. While CRISM's ground resolution (down to 18 m/px) is a significant advance, it remains insufficient for detailed, meter-scale studies. Other instruments (e.g., MRO HiRISE, CTX, TGO CaSSIS) offer superior spatial resolution but only provide limited panchromatic or multispectral data. The study explores the application of modern pansharpening algorithms for the enhancement of the spatial resolution of CRISM hyperspectral cubes based on CaSSIS images. For validation of this approach, the test dataset was brought to a spatial resolution of up to 4.5 m/px, achieving an increase in spatial resolution of up to 8 times the original. The analyses conducted show that despite the significant increase in resolution, the spectral quality of the data remains virtually unchanged, maintaining its usability and potentially implementing it for compositional and mineralogical interpretation. Both the alignment methods and the two pansharpening methods used, GSA and MTF-GLP, have been adapted for use with georeferenced data and are part of the PANCO open-source script suite. Although tested on CRISM, the developed tools can also be applied to a wide range of other remote sensing instruments for both planetary and terrestrial observations.