Why not use magnets while searching for meteorites: scientists’ answer

Hunters of precious meteorites usually use magnets to search for extraterrestrial rocks. But scientists warn that the use of magnets can destroy valuable scientific information that is contained inside them.

Magnets, which are popular tools for identifying meteorites, can overwrite the information that space rocks contain about the magnetic fields of their mother worlds. That’s what happened to the oldest known Martian meteorite (in the photo). Picture: NASA

Touching a meteorite with even a small magnet can erase any “records” of its mother body that are stored in a magnetic field, researchers report in the journal Geophysical Research: Planets. This concern is quite serious: a group of the oldest known Martian meteorites has already lost its magnetic memory.

By exploring meteorites, scientists can learn about other worlds in space. Space rocks may contain traces of planetary atmospheres, chemical building blocks for life, and so on. 

Sometimes scientists get fragments from Mars; they were carried into space by an impact millions of years ago, and then captured by Earth’s gravity. Only a few hundred such rocks are known to exist. Even rarer are samples containing minerals with imprints of the magnetic field of the Red Planet, which disappeared about 3.7 billion years ago. Therefore, the oldest known Martian meteorites, which date back about 4.4 billion years ago, give an amazing chance to study the magnetic field.

Destruction of evidence

But such unique research opportunities can be very easily negated. The team’s calculations and experiments with terrestrial rocks – substitutes for meteorites – confirm that the approach of a magnet to a rock can change the rotation of electrons inside. This rearrangement overwrites the imprint of the previous magnetic field, a process called remagnetization. 

The team examined nine meteorites found at different times and in different places on Earth. It is believed that they all originate from one of the oldest known pieces of Mars; it most likely disintegrated when it entered the Earth’s atmosphere. All of them were remagnetized.

Therefore, scientists urge meteorite seekers and other scientists not to use magnets if possible, in order to get as many space rocks as possible to shed light on the magnetic past of Mars.

Earlier we reported how an Australian tried to saw a meteorite for several years, believing that it was gold.

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