Chang'e-6 far-side melt rocks favor long decline in early Solar System impacts

Argon-argon dating of impact melt rocks returned by China's Chang'e-6 mission from the Moon's far side supports a long decline in asteroid bombardment rather than a single catastrophic late heavy bombardment, SciTechDaily reported, citing a Science Advances paper with Curtin University co-author Dr. Fred Jourdan. Until recently almost all lab-studied lunar samples came from the near side. Far-side material lets researchers compare regions with different geological histories. Jourdan said the Moon preserves a record erased on Earth by erosion, plate tectonics, and other processes, and that the far side keeps a cleaner archive of earliest impacts. The team studied tiny fragments recording impacts from about 4.33 billion to 1.13 billion years ago, covering more than three billion years of collisions. SciTechDaily said the samples strengthen the case that bombardment gradually weakened over billions of years as leftover debris cleared, rather than exploding in one brief storm. Because Earth and the Moon share a common region of the Solar System, major lunar impacts inform conditions on the young Earth even where terrestrial evidence is gone. Chang'e-6 was the first mission to return far-side samples. The paper carries DOI: 10.1126/sciadv.aee8718.