Chang'e-6 samples clarify geological differences on the Moon's far side.

Analyses of basalt and regolith returned by China's Chang'e-6 in June 2024 show isotopic evidence that a large early impact heated deep lunar material and altered volatile element abundances on the Moon's far side.

China's Chang'e-6 mission returned 1,935.3 grams of lunar regolith and rock to Earth in June 2024. Scientists at the Institute of Geology and Geophysics of the Chinese Academy of Sciences analyzed basalt from those samples. Their work focuses on how a massive early impact, associated with the South Pole–Aitken Basin about 4.25 billion years ago, affected deep lunar material. The team used high-precision isotope analysis to trace changes in volatile elements and isotope ratios. Key findings: - The returned basalts show isotopic variations that indicate high-temperature heating of deep lunar material linked to the basin-forming impact. - Moderately volatile elements such as potassium, zinc, and gallium show signatures consistent with loss by volatilization and isotopic fractionation at high temperatures. - Far-side basalts from Chang'e-6 have a higher proportion of the heavier potassium-41 isotope compared with Apollo near-side samples. - The researchers report that an early large-scale impact likely caused loss of lighter potassium-39 and enrichment of potassium-41 in the deep mantle, and that this volatile loss suppressed later volcanic activity on the far side. - The results reinforce conclusions that the Moon's near and far sides followed different evolutionary paths and are relevant to planning for exploration and potential sites in the South Pole–Aitken Basin. Summary: The study provides isotopic evidence that a major early impact heated deep lunar material and altered volatile element abundances, helping to explain compositional and volcanic differences between the near and far sides of the Moon. Undetermined at this time.