Transport of Volatiles in Agglutinates from Lunar Regolith of Chang’E-5 Mission

Volatiles transport in the lunar regolith is essential for lunar soil evolution and in-situ resources utilization (ISRU) and has not been fully understood. Here, we characterize a typical agglutinate particle from Chang’E-5 samples and demonstrate the transport behavior of volatiles through the porous structure. The results of surface and 3D structural characterization indicate that the formation of the smooth porous structure is mainly caused by volatiles flow. Based on the element distribution analysis, we further speculate the main component of the volatiles is gas water attributed to the reduction of FeO by abundant hydrogen in the superficial lunar regolith during micrometeoroids impacts. Numerical models of volatiles (gas water) transport in the porous agglutinate have been developed for different pressure conditions. The results show the ultrafast transport of volatiles makes the superficial regolith dry and barren under high-vacuum condition. We conclude that rapid escape of volatiles can hardly retain water in the superficial lunar soil yet provides opportunities for development of ISRU technology.