"As the first lunar sample obtained from the far side of the Moon, the Chang'e-6 sample will provide an unparalleled opportunity for lunar research," said Prof. Chunlai Li from the National Astronomical Observatories of the Chinese Academy of Sciences. These samples will help scientists better understand several critical aspects of lunar science, including the Moon's early evolution, the differences in volcanic activity between the nearside and farside, and the history of impacts in the inner solar system. "These insights are expected to lead to new concepts and theories regarding the origin and evolution of the Moon, and refine its use as an interpretive paradigm for the evolution of the terrestrial planets," Li added.

Scientists have collected a total of 382.9812 kg of lunar samples through six Apollo missions, three Luna missions, and the Chang'e-5 mission. These samples have been instrumental in advancing planetary science, providing essential data that links orbital observations with actual surface conditions. "Returned lunar samples are essential to planetary science research, as they provide key laboratory data to link orbital remote sensing observations to actual surface ground truth," said Li.

The analysis of lunar samples has led to several significant hypotheses, such as the giant impact theory for the Moon's origin, the Lunar Magma Ocean theory, and the Late Heavy Bombardment. However, until now, all collected samples have come from the nearside of the Moon, leaving the farside largely unexplored.

"Nearside samples alone, without adequate sampling from the entire lunar surface, especially from the farside, cannot fully capture the geologic diversity of the entire Moon. This limitation hampers our understanding of the Moon's origin and evolution," said Li. The Chang'e-6 mission successfully gathered 1935.3 grams of lunar material from the South Pole-Aitken basin on June 25, 2024, providing the first samples from the farside.

These samples were collected using a combination of drilling and scooping techniques, and subsequent analysis revealed that they consist of a mix of local basaltic materials and non-mare materials. The primary minerals found include plagioclase, pyroxene, and ilmenite, with only small amounts of olivine. The sample also contained fragments of basalt, breccia, and agglutinates, indicating a combination of volcanic activity and impact processes.

The lunar surface is categorized into three geochemical provinces: the Procellarum KREEP Terrane (PKT), the Feldspathic Highland Terrane (FHT), and the South Pole-Aitken Terrane (SPAT). The samples from Chang'e-6 are expected to provide new information about volcanic history and the composition of the lunar highland crust, as well as offering potential insights into the deep lunar mantle.

"These local mare basalts document the volcanic history of lunar farside, while the non-basaltic fragments may offer critical insights into the lunar highland crust, South Pole-Aitken impact melts, and potentially the deep lunar mantle, making these samples highly significant for scientific research," said Li.

Prior to the Chang'e-6 mission, lunar samples collected from the nearside, such as those from the Apollo, Luna, and Chang'e-5 missions, had only included materials from the PKT and FHT regions. The South Pole-Aitken basin on the farside, formed 4.2 to 4.3 billion years ago, is the largest confirmed impact basin in the solar system and has remained unexplored until now.

Research Report:Nature of the lunar farside samples returned by the Chang'e-6 mission

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