Work

Lunar Geochemistry from X-Ray Line Flux Ratios Using CLASS on Chandrayaan-2

Year: 2026

Type: article

Abstract: Global lunar chemical maps are essential for understanding the origin and evolution of the Moon, its surface characteristics, and its potential for resource extraction. While lunar elemental abundances have been successfully derived using model-dependent X-ray spectroscopy, these methods often require concurrent high-quality solar monitoring and intensive computational modeling, which can limit spatial coverage. Here we used X-ray fluorescence line intensities of O, Mg, Al, Si, Ca, and Fe derived from 5 yr of data from the Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) to generate global O/Si, Mg/Si, Al/Si, Mg/Al, Ca/Si, and Fe/Si line intensity ratio maps at a resolution of 5.3 km pixel −1 . We have developed an independent data analysis methodology for CLASS, based on open source Python packages. Our analysis shows that Mg/Al and Al/Si line intensity ratios serve as effective empirical proxies for major geochemical terranes, showing good correlation with published elemental maps, returned sample data, and the Apollo 15 and 16 X-ray Fluorescence Spectrometer (XRFS) maps. Further, we apply Gaussian mixture models to the Mg/Si versus Al/Si density maps to map geochemically distinct regions on the Moon that could be of interest for future investigations.

Source: The Planetary Science Journal

DOI: 10.3847/psj/aeb09a