Findings From Chang'e 6 Samples so Far
Water, volcanic, and other clues from the Moon.
China’s Chang’e 6 lunar far-side sample return mission began its lunar voyage in May 2024 and returned to Earth around fifty-three days later with 1935.3 grams of samples. The mission was the first to retrieve lunar samples from the far side of the Moon and bring them back to Earth for study, which has been underway since.
In the July 10th 2025 issue of the journal Nature, four papers regarding findings from the mission were included, although prepared months to weeks prior. New findings in the papers are related to volcanic activity, the Moon’s ancient magnetic field, water content across the Moon, and geochemical characteristics of the Moon’s mantle. At a Chinese Academy of Sciences press conference on July 9th, Wu Fuyuan, Researcher with the Institute of Geology and Geophysics as well as an Academician at the Chinese Academy of Sciences, stated that the four papers shed light on how the south pole of the Moon formed.
Also from the July 10th issue, the image on the cover of the issue was a stunning photomosaic, attached below, of the Moon’s far side and south pole assembled by Chunlai Li, Jianjun Liu, and Wei Yang from images taken by Chang’e 1.
The four papers part of the July 10th Nature issue are quite interesting, even for someone who has a limited understanding of planetary science (like me). Attached below are very brief summaries to the best of my understanding (which is what has taken this post a while to publish) and links to the full papers, which I encourage you to read.
Lunar farside volcanism 2.8 billion years ago from Chang’e-6 basalts1
The first paper shares that researchers analyzed basalt rock fragments and discovered evidence of two distinct periods of volcanic activity: very ancient volcanism about 4.2 billion years ago involving high-aluminum basalts, and a more recent main volcanic episode about 2.8 billion years ago. The 2.8 billion-year-old volcanism was particularly interesting because it's much younger than most known lunar volcanism and shows that volcanic activity on the Moon's far side continued for over 1.4 billion years, challenging previous theories about how long the Moon remained volcanically active.
A reinforced lunar dynamo recorded by Chang’e-6 farside basalt2
Next, the second paper analyzes the magnetic properties preserved in the lunar far side samples to theorize the Moon's ancient magnetic field. Researchers studied basalt fragments dating to about 2.8 billion years ago and discovered evidence of a strong lunar magnetic field at that time, stronger than previously expected. This finding reveals that after the Moon's magnetic field dramatically weakened around 3.1 billion years ago, it then rebounded and strengthened again, rather than simply continuing to decline as scientists had previously assumed.
Water abundance in the lunar farside mantle3
Meanwhile, the third paper studied volcanic rocks from the Moon’s far side to measure water content in its deep interior, revealing that the source mantle had only about 1 to 1.5 micrograms of water per gram, significantly lower than estimates from the nearside. The original lava that formed the basalts likely contained between 15 and 168 micrograms per gram of water. This finding suggests a hemispheric difference in the Moon’s internal water distribution, with the far side being much drier. Despite this, hydrogen isotope ratios are consistent across both sides of the Moon, indicating a common origin for lunar water, likely from asteroid material. These results challenge previous assumptions of a largely wet Moon and support a more complex picture of its formation and evolution.
Ultra-depleted mantle source of basalts from the South Pole–Aitken basin4
Lastly, the fourth paper found pieces of the Moon’s deep interior, called mantle olivine, on the surface of the far side for the first time. These mineral grains were discovered in a type of rock created by ancient impacts and are different from typical surface rocks, showing they came from deep inside the Moon. Their composition matches what scientists expected the Moon’s mantle to be like after it cooled from a molten state. This may confirm theories about the Moon’s layered structure and shows that large impacts were powerful enough to bring deep material to the surface.
By Qian W. L. Zhang, Mu-Han Yang, Qiu-Li Li, Yu Liu, Zong-Yu Yue, Qin Zhou, Liu-Yang Chen, Hong-Xia Ma, Sai-Hong Yang, Xu Tang, Guang-Liang Zhang, Xin Ren, and Xian-Hua Li.
By Shuhui Cai, Kaixian Qi, Saihong Yang, Jie Fang, Pingyuan Shi, Zhongshan Shen, Min Zhang, Huafeng Qin, Chi Zhang, Xiaoguang Li, Fangfang Chen, Yi Chen, Jinhua Li, Huaiyu He, Chenglong Deng, Chunlai Li, Yongxin Pan, and Rixiang Zhu.
By Huicun He, Linxi Li, Sen Hu, Yubing Gao, Liang Gao, Zhan Zhou, Mengfan Qiu, Disheng Zhou, Huanxin Liu, Ruiying Li, Jialong Hao, Hejiu Hui, and Yangting Lin.
By Qin Zhou, Wei Yang, Zhuyin Chu, Honggang Zhu, Saihong Yang, Xingguo Zeng, Ding-Shuai Xue, Li-Hui Jia, Guangliang Zhang, Hongbo Zhang, Yanhao Lin, Huijuan Zhang, Heng-Ci Tian, Peng Peng, Dan-Ping Zhang, Lixin Gu, Chunlai Li, and Fu-Yuan Wu.