Weak influence of the secondary surface processes on the regolith of Chang’E-5 landing site

Abstract

AbstractNoble gases in lunar soils provide critical information regarding solar wind and cosmic-ray interactions with the lunar surface, as well as the history of impact events affecting the regolith turnover processes. Here, we studied the characteristics of noble gases He, Ne, Ar in Chang’E-5 soil. High 4He/36Ar and 20Ne/36Ar values show that the soil has typical mare terrain characteristics. Furthermore, both values are higher than those in other lunar soils, suggesting the secondary processes occurring in the soil may have been less strong than in other lunar samples. Trapped (3He/4He) tr and (20Ne/22Ne) tr values were less fractionated than those of Apollo soils, also indicating the weak secondary processes the Chang’E-5 soil underwent. Trapped (40Ar/36Ar) tr values indicate the implanted solar wind was young. The integrated exposure times to solar wind of the soil on the lunar surface suggest the Chang’E-5 soil was not seriously admixed by sputtered material from nearby rocks.