Persistent but weak magnetic field at Moon's midlife revealed by Chang'e-5 basalt

TL;DR

This study uses Chang'e-5 basalt samples to demonstrate that the Moon had a weak but persistent magnetic field until about 2 billion years ago, indicating a long-lived lunar dynamo and interior thermal activity.

Contribution

It provides the first paleomagnetic evidence of a long-lived lunar dynamo extending into the Moon's midlife, based on the youngest mare basalt samples.

Findings

Weak paleointensities of 2-4 μT at 2 billion years ago

Evidence for a sustained lunar dynamo until midlife

Implication of ongoing thermal convection in the lunar interior

Abstract

The evolution of the lunar magnetic field can reveal the Moon's interior structure, thermal history, and surface environment. The mid-to-late stage evolution of the lunar magnetic field is poorly constrained, and thus the existence of a long-lived lunar dynamo remains controversial. The Chang'e-5 mission returned the heretofore youngest mare basalts from Oceanus Procellarum uniquely positioned at mid-latitude. We recovered weak paleointensities of 2-4 uT from the Chang'e-5 basalt clasts at 2 billion years ago, attestting to the longevity of a lunar dynamo until at least the Moon's midlife. This paleomagnetic result implies the existence of thermal convection in the lunar deep interior at the lunar mid-stage which may have supplied mantle heat flux for the young volcanism.