At 2:07 p.m. on 25 June, the Chinesesc Chang’e-6 spacecraft returned to Earth bearing the first samples collected from the Moon’s farside. The mission, run by the China National Space Administration (CNSA) could help scientists understand the drastic differences in nearside and farside geology, impact history, and evolution.

“The Chang’e-6 mission represents a significant milestone in the history of human lunar exploration, and it will contribute to a more comprehensive understanding of lunar evolution,” Wei Yang, a geochemist at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, told the Xinhua News Agency.

Second Farside Landing

Chang’e-6 landed in the southern mare of the Apollo basin, an impact crater 537 kilometres across that sits within the older SPA basin. The SPA basin is one of the largest and oldest impact features in the solar system and exemplifies the differences in the Moon’s hemispheres.

“There are significant differences between the farside and the nearside of the Moon in terms of lunar crustal thickness, volcanic activity, composition, etc.,” Zongyu Yue, a planetary geologist at the Chinese Academy of Sciences, said in a recent statement. Yue added that the Chang’e-6 samples “are expected to answer one of the most fundamental scientific questions in lunar science research: what geologic activity is responsible for the differences between the two sides?”

Chang’e-6 was China’s second farside landing, following Chang’e-4, which landed in the SPA basin in early 2019. That mission, which is ongoing, has studied shallow subsurface structure, detected lunar mantle material, and mapped ejecta material.

“My greatest hope is that the [Chang’e-6] samples contain some impact melts,” Yue said. That information would “not only help clarify the role of early lunar meteorite impacts on the Moon’s evolution, but also be of great significance in analysing the early impact history of the inner solar system.”