Moon’s magnetic pull lasted much longer than thought: Chinese study

Lunar samples gathered by China’s Chang’e-5 mission uncover fresh information that may provide essential clues about the habitability and evolutionary history of our celestial neighbor.

The magnetic field endured well into middle age, far beyond what was initially anticipated.

Researchers found that the moon’s magnetic field was between two and four microteslas about two billion years ago – roughly ten percent of the Earth’s magnetic field strength today. They shared their results in a Science Advances journal article on Thursday.

According to Ross Mitchell, co-author of the research from the Institute of Geology and Geophysics in Beijing, contrary to the assumption that the moon’s magnetic field had disappeared long ago, their study suggests it still persisted, albeit weakly.

Our new platform of carefully selected content with detailed explanations, frequently asked questions, in-depth analyses and informative graphics designed by our exceptionally skilled team.

According to Massachusetts Institute of Technology planetary scientist Benjamin Weiss, who was not part of the research, the moon’s weak but sustained magnetic field likely originated from prolonged interior processes such as the solidification of the moon’s core or interactions between its core and mantle.

These processes would have sustained the moon’s magnetic engine, referred to as the lunar dynamo, for billions of years.

“The moon goddess’s elixir appears to have achieved its intended effect,” Weiss wrote in a review article analyzing the results. He was referring to the Chang’e missions, which were named after the goddess who fled to the moon seeking refuge after stealing an elixir of immortality from the gods.

The discoveries imply that a long-lasting magnetic field may have protected the moon’s surface from solar radiation and allowed volatile compounds such as water to be retained.

Understanding such details of the moon’s past magnetic field offers valuable insights into planetary habitability and evolution.

NASA’s Apollo missions suggested that it was present approximately three billion years ago, with field strengths comparable to the current Earth’s magnetic field, which varies from 25 to 65 microteslas.

It remained unclear for how long the lunar dynamo functioned.

Studying this issue with the American Apollo samples has been difficult because of their relatively old age, large iron crystals that don’t preserve magnetic signals well, and other limitations, Weiss observed.

missions five decades ago.

For this study, the researchers selected nine tiny basalt pieces – each measuring 3-8 millimeters in size and weighing less than 0.3 grams.

These fragments functioned like magnetite recorders, holding onto the magnetic field that existed when the rocks were originally formed billions of years ago. The researchers then utilized highly sensitive laboratory methods to extract the ancient magnetic signals.

“When it comes to magnetism, small sample sizes result in weak signals, necessitating intricate, time-consuming laboratory work,” said lead author Cai Shuhui, a colleague of Mitchell’s at the Institute of Geology and Geophysics.

“They simply were good enough,” she said

The magnetic strength of two to four micTesla contrasted sharply with the significantly stronger magnetic fields of the moon’s early history, which reached tens of micTesla.

The magnetic field proved to be greatly stronger than previously predicted measures.

A magnetic field produced by the moon’s core suggests that the region’s deep interior was still hot enough to cause the puzzling volcanic activity observed in the samples collected by the Chang’e-5 mission.