Exposure age and SW fluxes. (a) The exposure Age (Myr) versus the maturity index I_s/FeO. The exposure age data for the CE5 and CE6 landing sites were obtained from R. Liu et al. (2025); the data for Apollo 11 10,084 and Apollo 16 67,701 were obtained from L. P. Keller et al. (2021). All of the Apollo 17 data came from J. A. McFadden & M. S. Thompson (2026). The maturity index I_s/FeO of all Apollo samples is provided by R. Morris (1978b). (b) The relationship between the maturity index I_s/FeO and J (which represents the average normalized SW number flux). (c) The maturity index I_s/FeO versus E (which represents the average normalized SW energy flux). Due to partial shielding by lunar magnetic anomalies, the Apollo 16 soils exhibit lower E (A. Vorburger et al. 2012; L. Xie et al. 2023; R. Liu et al. 2025). The maturity of Apollo 16 soils represents the average value compiled from six samples provided by LSCC. The maturity data of Apollo 11 soils is the average value sourced from R. Morris (1978b).