Rock samples from the moon's far side, collected by China's Chang'e-6 lunar probe, have unveiled groundbreaking insights into the moon's magnetic history.
Published in Nature on Thursday, the study highlights a surprising resurgence in the moon's magnetic field 2.8 billion years ago, following a significant decline around 3.1 billion years ago. This challenges the prevailing theory that the lunar dynamo remained in a low-energy state after its earlier weakening.
These results mark the first-ever paleomagnetic data obtained from the moon's far side, offering a deeper understanding of the lunar dynamo – the geophysical process responsible for generating the moon's magnetic field in the past.
On June 25, Chang'e-6 returned to Earth with 1,935.3 grams of samples from the moon's far side, an area previously unexplored.
Researchers from the Institute of Geology and Geophysics (IGG) under the Chinese Academy of Sciences analyzed four basalt fragments from the mission and detected an increase in paleomagnetic field strength. This suggests a possible reactivation of the lunar dynamo after its initial decline, potentially due to changes in the dynamo's energy sources or a revival of its driving forces.
Satellite and lunar surface data indicated that the moon no longer possesses a global dipole magnetic field. Earlier studies revealed that the moon's magnetic field, once comparable to Earth's between 4.2 and 3.5 billion years ago, underwent two significant declines before ultimately ceasing entirely after 1 billion years ago.
However, questions remain regarding the precise timeline, duration, and mechanisms driving the moon's magnetic field, highlighting gaps in understanding the moon's far side.
\"Understanding the evolution of the lunar dynamo is of great significance for revealing the moon's internal structure, thermal history, and surface environment,\" said Cai Shuhui from the IGG, the corresponding author of the study.
A peer-reviewer of the paper noted that the team's \"highly original results\" fill a billion-year-long gap in the lunar paleomagnetic record and provide \"the first paleomagnetic measurements from the lunar far side,\" representing \"a major advance in our understanding of lunar magnetism.\"
These findings build on other significant discoveries from Chang'e-6. In November, an IGG team reported two volcanic events on the moon's far side, occurring 2.8 billion and 4.2 billion years ago, also published in Nature.
Another study, published in Science, confirmed that the low-titanium samples collected by Chang'e-6 are approximately 2.83 billion years old, offering further evidence of volcanic activity on the moon's far side.
Reference(s):
Chang'e-6 moon samples unveils surprising magnetic field resurgence
cgtn.com
