Old Apollo rocks shed new light on the moon's magnetic field long ago

Old Apollo rocks are providing a fresh take on the moon's magnetic field

CAPE CANAVERAL, Fla. -- Lunar rocks collected by Apollo astronauts more than half a century ago are providing a fresh take on the moon's mysterious magnetic field, scientists reported Wednesday.

Samples to be retrieved by future moonwalkers in NASA’s new Artemis program should yield even more clues. Four Artemis astronauts are expected to fly around the moon in a crucial test flight, blasting off as early as April from Kennedy Space Center after weeks of delays.

The study by University of Oxford researchers in England suggests that while the moon’s magnetic field has been weak during most of its existence, it strengthened and even exceeded Earth’s magnetic activity during extremely brief periods 3 billion to 4 billion years ago. Their findings appear in the journal Nature Geoscience.

Magnetic fields help to shield against dangerous cosmic rays and, in the case of Earth, the sun's harsh radiation as well.

The moon had “incredibly short spikes in high magnetic field strength” lasting no more than 5,000 years and possibly as short as a few decades, the result of melting titanium-rich rocks deep within the moon, said lead author Claire Nichols.