Transport of Volatiles in Agglutinates from Lunar Regolith of Chang'e-5 Mission

Agglutinate particles, an important component resulting from micrometeoroids impacts, account for about 13.4% to 84.7% of the volume of lunar regolith depending on its maturity. They are crucial in the soil's evolution and the migration of volatile substances. Here, we examined a representative agglutinate particle from Chang'e-5 samples and modeled how volatiles move through its porous framework. Our analysis revealed that the agglutinate's surface features a patchy distribution of smooth, open pores, as shown by both surface and 3-dimensional structural assessments. By integrating elemental distribution data, we propose that the formation of these smooth, open pores is primarily due to the flow of gaseous volatiles, byproducts of intricate physiochemical reactions occurring in the lunar surface layer during impacts by micrometeoroids. Numerical models of volatile transport in the porous agglutinate have been developed for different flow regimes. These models demonstrate that under the intense conditions of impacts, the transport of volatiles occurs at a remarkably high velocity. Consequently, it is improbable that water would accumulate within the porous structure of lunar soil agglutinates. Nevertheless, understanding this process is valuable for gaining a deeper understanding of the lunar regolith's development and for potential future endeavors in extracting water from the lunar surface.