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The surface of the Moon. Credit: ESA/Silicon - Worlds/Daniele Gasparri

Published: 26 February 2026

New study published

by Fabio Crameri

Press releases

Highlights

Johannes Geiss Fellowship

Publication

Moon

Apollo

Magnetism

Congratulations to ISSI Johannes Geiss Fellow 2026 Claire Nichols

ISSI warmly congratulates Claire Nichols, ISSI Johannes Geiss Fellow 2026, on the publication of her new paper in Nature Geoscience: “An intermittent dynamo linked to high-titanium volcanism on the Moon.”

The study, led from the University of Oxford and based on analyses of samples returned by the Apollo program, resolves a decades-long debate about the strength of the Moon’s ancient magnetic field.

Solving a long-standing lunar puzzle

For years, researchers have disagreed over whether the Moon possessed a strong global magnetic field 3.5–4 Billion years ago. Some Apollo samples appeared to record fields even stronger than Earth’s, while theoretical considerations suggested that the Moon’s small core should only have sustained a weak dynamo.

Claire and her colleagues demonstrate that both camps were, in fact, correct.

Their analysis of mare basalts reveals a striking link between titanium content and recorded magnetic field strength. Samples with high titanium concentrations consistently preserve evidence of very strong magnetic fields, whereas low-titanium samples record weak fields. The team proposes that melting of titanium-rich material at the Moon’s core-mantle boundary intermittently powered an intense but short-lived dynamo, lasting at most a few thousand years, and possibly only decades.

Crucially, because the Apollo missions preferentially sampled titanium-rich mare basalts from relatively flat landing sites, the returned collection is biased towards these rare high-field episodes. What appeared to represent hundreds of millions of years of strong magnetism may instead reflect brief and exceptional bursts in an otherwise weak-field lunar history.

Relevance to ISSI research

Claire’s work exemplifies the kind of interdisciplinary, sample-based planetary science that ISSI fosters: By combining petrology, geochemistry, palaeomagnetism and dynamo theory, the study bridges laboratory analysis of returned samples with global-scale models of planetary evolution.

During her tenure as ISSI Johannes Geiss Fellow 2026, Claire is engaging with the ISSI community on questions surrounding planetary magnetism, dynamo intermittency, and the interpretation of sample-return data — themes that resonate strongly with ISSI’s tradition of advancing international collaboration in space science. Her findings also have direct implications for future lunar exploration, including sample selection strategies for upcoming missions.

We congratulate Claire on this important contribution to lunar science and look forward to the discussions it will inspire within the ISSI community, such as the ones held this week here in Bern amongst the ISSI International Team 645.

🔗 Read the paper: An intermittent dynamo linked to high-titanium volcanism on the Moon, Nature Geoscience (26 February 2026).
🔗 Read the University of Oxford press release: “Solved: New analysis of Apollo Moon samples finally settles debate about lunar magnetic field.”

Credits ESA/Webb, NASA & CSA, A. Martel