Fig. 4: Morphometrics of diverse particle types in CE5 and CE6 soils.

a Representative 3D morphologies of each of the seven lunar regolith particle types—basalt, breccia, agglutinate, Hm, Mm, Lm, and glass beads—identified via our machine learning approach of lunar bulk soil. b Morphometrics statistical distributions for rock particles (basalt, breccia, and agglutinate) in bulk soil and LRS (IGG-01). c Morphometrics statistical distributions for monomineralic particles (Hm, Mm, and Lm) in bulk soil. Size-dependent effects on morphometrics were specifically investigated for Mm and Lm particles by subdividing them into large (solid lines) and small (dashed lines) size groups. Comparisons between nearside and farside samples reveal highly similar mean values, standard deviations, and distribution ranges across all particle types. d Boxplots comparing the overall regularity (OR) of six particle types in nearside and farside bulk soils. Black lines indicate medians; boxes represent the lower and upper quartiles; whiskers denote the full range of the distributions. The shaded region highlights the concentration OR range for “simple particles.” Agglutinate and breccia particles show considerably lower OR values compared to other particle types. In general, the OR distributions for CE5 and CE6 are very similar, with slightly more regular particle shapes observed in the CE6 regolith. e Volume fractions of each particle type in the CE5 and CE6 regolith bulk soil samples were determined in this study. Owing to a higher degree of space weathering at the CE6 landing site, it contains approximately ~9% more agglutinates and ~4% more breccia than the CE5 regolith.