The Chang’e-6 mission has provided new insights into the ancient lunar magnetic field. As reported in Nature, basalts from the moon’s farside, dated to 2.8 billion years ago (Ga), show a notable resurgence in the lunar magnetic field’s strength. These findings challenge prior beliefs about the lunar dynamo, suggesting an unexpectedly active phase in its evolution during this period. This study marks the first-ever paleomagnetic analysis conducted on farside lunar samples.

This work is published in Nature. Led by Professor Zhu Rixiang, a team at the Institute of Geology and Geophysics under the Chinese Academy of Sciences (CAS) examined the samples returned by the mission. Associate Professor Cai Shuhui and her colleagues measured the magnetic field strength within these basalts, recording values ranging from 5 to 21 microteslas (µT).

According to a report by Phys.org, this data indicates a sharp increase in the lunar magnetic field’s intensity around 2.8 Ga, following a period of decline observed at approximately 3.1 Ga. The study’s findings contradict earlier models that posited a sustained weakening of the lunar dynamo after 3 Ga, adding complexity to our understanding of the moon’s thermal and geological history.

Proposed Drivers of Magnetic Activity

The resurgence of the magnetic field has been attributed to possible mechanisms, such as a basal magma ocean or precessional forces. Core crystallization may have also contributed to the prolonged activity. The researchers suggest these processes kept the moon’s deep interior geologically active for a longer period than previously believed.

Implications for Future Lunar Exploration

By providing critical data on the lunar magnetic field’s intermediate evolutionary stages, this research highlights significant fluctuations between 3.5 and 2.8 Ga. The findings may guide future exploration missions in understanding the moon’s magnetic reversals and deep interior dynamics. These advancements offer a deeper perspective on the moon’s evolutionary timeline, enriching scientific knowledge for years to come.