Scientists reveal volcanic history of lunar far side

Chinese scientists have found that magma activity occurred 4.2 billion years ago on the moon's far side and lasted for at least 1.4 billion years, a discovery that has further enhanced scientists' understanding of lunar evolution.

Two related studies based on the samples retrieved from the lunar far side by the Chang'e 6 mission were simultaneously published on Friday in the international academic journals Nature and Science.

The studies indicated significant differences between the near and far sides of the moon in terms of morphology, composition and magma activity, offering a key direction for lunar research.

"Unraveling the volcanic history of the lunar far side is crucial for understanding the hemispheric dichotomy of the moon," said Li Qiuli, a professor at the Chinese Academy of Sciences' Institute of Geology and Geophysics.

Previously, scientific understanding of the lunar far side was primarily based on remote-sensing studies. In June, the Chang'e 6 robotic lunar probe returned to Earth with nearly 2 kilograms of samples collected for the first time from the South Pole-Aitken Basin — the largest, deepest and oldest basin on the moon.

Since 2021, Chinese scientists have used lunar samples retrieved by the Chang'e 5 robotic probe to prove that significant magma activity occurred on the near side of the moon 2 billion years ago, and that minor volcanic activity happened even 120 million years ago.

In the study published in Nature, a team from the Institute of Geology and Geophysics and the National Astronomical Observatories of the CAS showed evidence of magma activity on the lunar far side, from 4.2 billion years to 2.8 billion years ago, through dating research on 108 basaltic rock fragments found in 5 grams of lunar soil retrieved by the Chang'e 6 probe.

The study published in Science, which was conducted by a team led by Xu Yigang, an academician of the CAS and a researcher at its Guangzhou Institute of Geochemistry, also confirmed magma activity on the lunar far side 2.8 billion years ago.

It further indicated that the eruption of lunar mare basalt was influenced by the internal composition of the moon, explaining why the South Pole-Aitken Basin on the far side lacks abundant volcanic activity.

Science reviewer Katherine Joy said these samples are the first to be collected from the lunar far side and, therefore, provide a unique view of the moon's geological history.

"The results are novel and are deserving of publication in Science. They will be of interest to a broad readership," she added.

yandongjie@chinadaily.com.cn