Elemental analyses of feldspathic to basaltic soils and rocks on the moon using laser-induced breakdown spectroscopy

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy 2024-11, Vol.221, p.107049, Article 107049
• Main Authors: Yumoto, K., Cho, Y., Ogura, J.A., Kameda, S., Niihara, T., Nakaoka, T., Kanemaru, R., Nagaoka, H., Tabata, H., Nakauchi, Y., Ohtake, M., Ueda, H., Kasahara, S., Morota, T., Sugita, S.
• Format: Article
• Language: English
• ISSN: 0584-8547
• DOI: 10.1016/j.sab.2024.107049

In-situ analysis of major elements using laser-induced breakdown spectroscopy (LIBS) is essential for future lunar landing missions, yet its performance under lunar conditions remains not fully understood. This uncertainty arises from the absence of an atmosphere and the diverse range of surface materials, which vary in chemical composition from anorthosites to basalts, and in physical properties from fine regolith to boulders. To address these challenges, we developed and cross-validated a multivariate LIBS calibration model by measuring 169 compressed fine powders of geologic samples under vacuum. These samples fully encompass the bulk composition range of lunar meteorites. We investigated the applicability of the model to a wider range of samples by measuring lunar meteorites, terrestrial anorthites, and lunar simulants in various physical forms, including rock chips and soils with different grain sizes and bulk densities. For powder samples, the quantification accuracy, assessed using root mean squared error (RMSE), resulted in 2.5 wt% SiO2, 0.25 wt% TiO2, 1.2 wt% Al2O3, 1.3 wt% MgO, 1.2 wt% CaO, 0.33 wt% Na2O, 0.47 wt% K2O (0.060 wt% K2O in the