Application of chemometrics on Raman spectra from Mars: Recent advances and future perspectives

The SuperCam and SHERLOC instruments onboard the NASA/Perseverance rover are returning the first Raman spectra to be ever collected from another planet. Similarly, the RLS instrument onboard the ESA/Rosalind Franklin rover will collect Raman spectra from powdered rocks sampled from the subsurface of Mars. To optimize the scientific exploitation of Raman spectra returned from planetary exploration missions, tailored chemometric tools are being developed that take into account the analytical capability of the mentioned Raman spectrometers. In this framework, the ERICA research group is using laboratory simulators of SuperCam and RLS to perform representative laboratory studies that will enhance the scientific outcome of both Mars2020 and ExoMars missions. On one hand, preliminary studies proved the chemometric analysis of RLS datasets could be used to obtain a reliable semi-quantitative estimation of the main mineral phases composing Martian geological samples. On the other hand, it was proved the data fusion of Raman and LIBS spectra gathered by SuperCam could be used to enhance the discrimination of mineral phases from remote geological targets. Besides describing the models developed by the ERICA group, this work presents an overview of the complementary chemometric approaches so far tested in this field of study and propose further improvements to be addressed in the future.