Lunar regolith samples contain fragments of endogenic rocks and exogenous meteorites. We report the first discovery of a chondrule fragment preserved in Chang'e-5 (CE-5) regolith samples. Forsterite and enstatite phenocrysts have extremely high Mg# (> 99) and high Mn/Fe ratios in this chondrule fragment. Its glass mesostasis is heterogeneous and contains hydrogen and carbon, as indicated by Raman peaks. The mineral assemblage, chemical composition, and oxygen isotope anomaly of this fragment are similar to those of type-I chondrules from carbonaceous chondrites. This fragment and other chondritic relics with 3.4 Ga. This contrast suggests that there may have been a change of impactors to the Earth-Moon system during the Imbrian period. Furthermore, this CE-5 chondrule fragment is a direct record of volatile addition to the Moon's surface from meteorites during the Eratosthenian period.

Knowledge regarding the abundance and distribution of solar wind (SW)-sourced water (OH/H2O) on the Moon in the shallow subsurface remains limited. Here, we report the NanoSIMS measurements of H abundances and D/H ratios on soil grains from three deepest sections of the Chang'E-5 drill core sampled at depths of 0.45-0.8 m. High water contents of 0.13-1.3 wt.% are present on approximately half of the grain surfaces (topmost similar to 100 nm), comparable to the values of Chang'E-5 scooped soils. The extremely low delta D values (as low as -995 parts per thousand) and negative correlations between delta D and water contents indicate that SW implantation is an important source of water beneath the lunar surface. The results are indicative of homogeneous distribution of SW-derived water in the vertical direction, providing compelling evidence for the well-mixed nature of the lunar regolith. Moreover, the findings demonstrate that the shallow subsurface regolith of the Moon contains a considerable amount of water.

Remote sensing data revealed that the presence of water (OH/H2O) on the Moon is latitude-dependent and probably time-of-day variation, suggesting a solar wind (SW)-originated water with a high degassing loss rate on the lunar surface. However, it is unknown whether or not the SW-derived water in lunar soil grains can be preserved beneath the surface. We report ion microprobe analyses of hydrogen abundances, and deuterium/hydrogen ratios of the lunar soil grains returned by the Chang'e-5 mission from a higher latitude than previous missions. Most of the grain rims (topmost similar to 100 nm) show high abundances of hydrogen (1,116 to 2,516 ppm) with extremely low delta D values (-908 to -992 parts per thousand), implying nearly exclusively a SW origin. The hydrogen-content depth distribution in the grain rims is phase-dependent, either bell-shaped for glass or monotonic decrease for mineral grains. This reveals the dynamic equilib-rium between implantation and outgassing of SW-hydrogen in soil grains on the lunar surface. Heating experiments on a subset of the grains further demonstrate that the SW-implanted hydrogen could be preserved after burial. By comparing with the Apollo data, both observations and simulations provide constraints on the governing role of temperature (latitude) on hydrogen implantation/migration in lunar soils. We predict an even higher abundance of hydrogen in the grain rims in the lunar polar regions (average similar to 9,500 ppm), which corresponds to an estimation of the bulk water content of similar to 560 ppm in the polar soils assuming the same grain size distribution as Apollo soils, consistent with the orbit remote sensing result.