Lunar surface and subsurface water revealed by Chang’e-6

Abstract The processes driving the formation and distribution of lunar water (OH/H 2 O), particularly in the subsurface, remain poorly understood. An opportunity to study subsurface water comes from lander plumes, which can displace and expose millimetre- to centimetre-sized regolith during the descent of the lander. Here we analyse data from the Chang’e-6 landing site and find that plume-disturbed areas exhibit distinct temperature and water-content patterns, which are driven by the redistribution of fine regolith. The average water content of the exposed fine regolith of the shallow subsurface is ~76 ppm, which is lower than the surface abundance of ~105 ppm measured at the surface. The Chang’e-6 landing site also contains on average approximately twice the water content than the Chang’e-5 one. Temporal variations of water content are observed at identical locations but different local times, exhibiting a minimum at local noon. We suggest that the differences in water content are correlated with the regolith glass abundance, particle sizes, depths and local times, reinforcing the hypothesis that solar wind implantation and impact gardening govern lunar water formation and distribution.