Chang'e-6 study highlights dynamic history of lunar magnetic field
by Simon Mansfield
Sydney, Australia (SPX) Dec 27, 2024

A study of farside basalts returned by China's Chang'e-6 mission has unveiled evidence of a significant resurgence in the Moon's magnetic field approximately 2.8 billion years ago (Ga). This discovery offers key insights into the lunar dynamo and its impact on the Moon's interior and surface evolution.

The Chang'e-6 mission provided the first basalt samples from the Moon's farside, filling a critical gap in our understanding of the lunar magnetic field's history. Previous studies of nearside samples have mapped a general timeline of the Moon's magnetic field but left uncertainties regarding its evolution.

Led by Prof. ZHU Rixiang of the Chinese Academy of Sciences (CAS) and Associate Professor CAI Shuhui, researchers performed paleomagnetic analyses on these samples. They measured ancient magnetic field strengths ranging from 5 to 21 microteslas (uT). The results showed a resurgence in magnetic intensity at 2.8 Ga, following a decline around 3.1 Ga. These findings challenge the widely held view that the lunar dynamo weakened after 3 Ga and remained inactive.

The researchers suggest that this magnetic revival could have been driven by a basal magma ocean or precessional forces, with potential contributions from core crystallization. These mechanisms indicate the Moon's interior remained geologically active well into its mid-early history.

This work marks the first paleomagnetic data derived from the Moon's farside. By integrating these findings with earlier data, the study identifies significant fluctuations in the lunar magnetic field between 3.5 and 2.8 Ga, suggesting a highly unstable dynamo during this period.

The implications extend to future lunar exploration, particularly in understanding magnetic field reversals and the Moon's thermal history. This research was conducted in partnership with the National Astronomical Observatories, CAS, with lunar samples supplied by the China National Space Administration. Support came from the National Natural Science Foundation of China, the Strategic Priority Research Program of CAS, and the Institute of Geology and Geophysics, CAS.

Research Report:A reinforced lunar dynamo recorded by Chang'e-6 farside basalt

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