You Shouldn’t Use Magnets When Looking for Meteorites. Here’s Why

Credits: NASA

Meteorite enthusiasts, it’s high time to abandon your magnets. Relying on them to spot celestial stones might obliterate invaluable scientific data.

Even a brief contact with a tiny magnet can potentially wipe out the historical magnetic record stored within a meteorite, revealing details about its originating celestial body, according to a study published in the April edition of the Journal of Geophysical Research: Planets.

This is not just a hypothetical concern: some of the most ancient Martian meteorites seem to have already lost their magnetic histories, the study highlighted.

Meteorites are frequently studied by scientists to glean insights about distant celestial bodies as well as to enhance our understanding of Earth. These interstellar fragments may preserve traces of extraterrestrial atmospheres, essential chemical elements of life, and other treasures.

Foteini Vervelidou, a planetary scientist, delves into Martian meteorites — fragments ejected from Mars due to a collision that eventually gravitated towards Earth — to unravel its primordial history.

Only a handful, in the range of a few hundred, are identified. Even scarcer are samples preserving traces of Mars’ erstwhile magnetic field, which disappeared around 3.7 billion years ago.

Such age-old Martian meteorites, tracing back approximately 4.4 billion years, offer a golden opportunity to explore this magnetic field, remarks Vervelidou, affiliated with MIT and the Institute of Earth Physics in Paris.

However, Vervelidou and her team emphasize the ease with which such rare chances can be squandered. Through simulations and terrestrial rock experiments — proxies for meteorites — the researchers found that the mere proximity of a hand-held magnet can alter the electronic spin within the rock.

This modification erases any existing magnetic signatures, a phenomenon termed as remagnetization.

Additionally, this alteration seems rampant. The research team scrutinized nine meteorites, discovered at diverse times and locations on our planet. Each is believed to have stemmed from Mars’ oldest identified fragment, which likely fragmented upon entering Earth’s atmosphere.

Astonishingly, all exhibited signs of remagnetization. While these findings are unfortunate, they aren’t unexpected, comments Melinda Hutson, a meteoriticist at Portland State University in Oregon and overseer of the Cascadia Meteorite Laboratory, who wasn’t part of the study.

However, it’s feasible to assess a meteorite without jeopardizing its magnetic traits. Vervelidou employs an apparatus known as a susceptibility meter in her laboratory, gauging an object’s reaction to magnetic fields.

Compact versions are also available: Vervelidou and her colleagues deployed one during their recent Chile expedition, identifying almost 1,000 meteorites. She remains optimistic that some of these cosmic fragments will unravel mysteries of Mars’ bygone magnetic era.