Size, morphology, and composition of lunar samples returned by Chang’E-5 mission

This study focuses on the physical and chemical properties of surficial lunar regolith (LR) samples returned from the Moon by the Chang’E-5 (CE-5) mission. Insights regarding the effect of a new sampling geological site on the surficial lunar sample CE5C0400 were illustrated using nondestructive techniques such as laser diffractometry coupled with image analysis, X-ray computed tomography, and field emission scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction combined with Rietveld refinement. From the characterization analyses, the CE-5 sampling site in the northeastern Oceanus Procellarum on the Moon yields a unique collection of relatively regular-shaped and fine basalt-dominated particles. The median grain size D50 is (55.24±0.96) µm, falling within the relatively low end of the range of the Apollo lunar returned samples. The coefficient of uniformity Cu of 15.1 and the coefficient of curvature Cc of 1.7 could classify CE5C0400 to be well-graded. The minerals in CE5C0400 comprise approximately 44.5% pyroxene, 30.4% plagioclase, 3.6% olivine, and 6.0% ilmenite. There is a relatively low content of approximately 15.5% glass phase in the CE-5 lunar sample. From the results, we deduce that the CE-5 LR structure could have mainly resulted from micrometeoroid impacts to achieve such a high level of maturity.