24/7 Space News
IRON AND ICE
A message to meteorite hunters: Put down your magnets!
Black Beauty, or NWA 7034, is thought to have formed at a time when the Red Planet harbored a magnetic field, much like the Earth does today. If the rock bears any trace of Mars' ancient field, this could give scientists valuable clues to the planet's past climate and composition.
Reuters Events SMR and Advanced Reactor 2025
A message to meteorite hunters: Put down your magnets!
by Jennifer Chu | MIT News
Boston MA (SPX) Apr 21, 2023

Each year, thousands of space rocks pierce through the Earth's atmosphere and hit the ground as meteorites. These fragments of comets and asteroids can land anywhere but are most often spotted in open terrain, such as the deserts of Africa and the Antarctic blue ice, where a meteorite's blackened exterior can stand out.

Still, these extraterrestrial remnants can resemble Earth rocks, and to tell the difference meteorite hunters often expose their "finds" to hand magnets, which can attract more strongly to metal-rich meteorites than to terrestrial rocks. Meteorite hunters, dealers, collectors, and curators often rely on hand magnets to verify a meteorite's identity.

But a new MIT study finds that the same magnets used to identify a meteorite usually erase its magnetic memory. They show that exposure to a magnet can reorient a rock's microscopic grains, undoing their original orientation and any trace of its magnetic origins.

The researchers make their case with Northwest Africa (NWA) 7034, a meteorite known in collectors' circles as "Black Beauty" for its obsidian exterior. Multiple shards of the meteorite were first discovered in the deserts of northwest Africa, and scientists determined that the rock contained crystals that formed on Mars more than 4.4 billion years ago.

Black Beauty is thought to have formed at a time when the Red Planet harbored a magnetic field, much like the Earth does today. If the rock bears any trace of Mars' ancient field, this could give scientists valuable clues to the planet's past climate and composition.

Unfortunately, the MIT team found that multiple samples of Black Beauty have been remagnetized since landing on Earth, and that any hint of an ancient Martian field has been wiped clean.

"There was an incredible record there, and a unique opportunity to understand the early history of Mars' magnetism," says study author Benjamin Weiss, professor of planetary sciences at MIT. "But we found it's all been obliterated by magnets."

With their new study, appearing this week in the Journal of Geophysical Research: Planets, the researchers hope to raise awareness in the planetary science community about the destructive effects of hand magnets. Weiss' co-authors are MIT postdoc Foteini Vervelidou and France Lagroix of the Paris Institute of Planetary Physics.

Dead ends
Tens of thousands of meteorites have been discovered to date. Nearly every found meteorite has been traced to about 100 parent bodies across the solar system, including asteroids, the moon, and Mars. Scientists attempting to read the history of these rocks have only recently come to realize that some interpretations were way off the mark, due to the influence of hand magnets.

For instance, samples of Allende, the largest and most studied meteorite on Earth, bear traces of exposure to a strong magnetic field. Scientists assumed this field was evidence that the meteorite formed long ago in a solar nebula that hosted an extremely high magnetic field. Only later did they realize that hand magnets were to blame for the meteorite's curiously strong pull.

Weiss has also been duped by artificially reset rocks. When he first joined the MIT faculty, he discovered signs of strong magnetism in fallen samples of an asteroid. The findings would have been the first evidence that asteroids can differentiate and form metallic cores like the Earth. But he later discovered, much to his frustration, that the meteorite had been reset by hand magnets.

"There's a long history of dead ends and confusion over remagnetized rocks," Weiss says.

For the MIT team, the tipping point came with NWA 7034. In 2014, fellow paleomagnetist Jerome Gattacceca measured a sample of Black Beauty and found its original magnetism, which was set more than 4.4 billion years ago, had been entirely undone by much stronger hand magnets on Earth. Weiss and Vervelidou recently analyzed numerous other samples of Black Beauty, hoping to find at least one magnetically preserved sample.

"Our initial hope was that by testing as many [samples] of this meteorite as possible, we would end up finding a few non-remagnetized ones," Vervelidou says. "Once we concluded that all of the samples we studied have been remagnetized, the motivation was to spread the word about the destructive effects of hand magnets."

Shifting a field
In their new study, the team laid out the ways in which hand magnets can affect a rock's natural magnetism. They first developed a numerical model, based on the physics of magnetism, to calculate the field surrounding a typical hand magnet and how it affects rocks of various sizes.

They then carried out experiments, exposing samples of the same terrestrial rock to magnetic fields of varying strengths and at various distances, and measured how each sample's inherent magnetism changed in response. These measurements matched the model's predictions, showing that the model can be used to determine whether a rock has been remagnetized. The model can also be used to estimate, based on a rock's magnetization, the depth at which a rock may still be unaffected.

Finally, the team reported their measurements of nine Black Beauty samples and confirmed with their model that every found piece of the meteorite had indeed been exposed to hand magnets.

"What we have in this paper is finally a clear, unambiguous work plan for establishing whether your rock has been hit by a magnet," Weiss says.

Instead of hand magnets, the researchers are recommending that meteorite hunters, collectors, and museum curators use susceptibility meters - handheld instruments that have been shown to quickly and accurately identify a meteorite without scrambling its magnetic memory.

Weiss acknowledges that susceptibility meters are a hard sell - commercial models are worth several thousand dollars, compared to some hand magnets that cost next to nothing. Within the meteorite trade, he hopes first to convince people upstream, such as museum curators and collectors. From there, word may trickle down to those making discoveries on the ground.

"There's been this incredible explosion of meteorite diversity and number in the last 20 years or so, and we owe meteorite hunters a thanks for finding these things," Weiss says. "But the tradeoff, the devil's bargain, is that often they are using magnets to find them, and are immediately destroying their magnetic record in the process."

This research was funded, in part, by the European Union's Horizon 2020 research and innovation program.

Research Report:"Hand magnets and the destruction of ancient meteorite magnetism"

Related Links
MITDepartment of Earth, Atmospheric and Planetary Sciences
Asteroid and Comet Mission News, Science and Technology

Subscribe Free To Our Daily Newsletters
Tweet

RELATED CONTENT
The following news reports may link to other Space Media Network websites.
IRON AND ICE
Two meteorites are providing a detailed look into outer space
Indianapolis IN (SPX) Mar 28, 2023
If you've ever seen a shooting star, you might have actually seen a meteor on its way to Earth. Those that land here are called meteorites and can be used to peek back in time, into the far corners of outer space or at the earliest building blocks of life. Today, scientists report some of the most detailed analyses yet of the organic material of two meteorites. They've identified tens of thousands of molecular "puzzle pieces," including a larger amount of oxygen atoms than they had expected. The r ... read more

IRON AND ICE
Russian cosmonauts take spacewalk outside of ISS

Northrop Grumman's S.S. Sally Ride departs International Space Station

Calnetix Technologies' high-speed blower system installed on ISS

Next-Gen suit for NASA's work for space station missions debuts

IRON AND ICE
Phantom Space selects Arnhem Space Centre for new dedicated launch site

Aerojet Rocketdyne to provide propulsion for three additional Orion spacecraft

Musk forms X.AI artificial intelligence company

Rocket Lab to take big step towards Electron reusability with pre-flown engine

IRON AND ICE
Making Tracks up Marker Band Valley: Sols 3803-3804

Clouds Above, Contact Science Below: Sols 3800-3802

Two Steps Forward, One Step Back: Sols 3805-3806

Hey Percy, look at those boulders

IRON AND ICE
China's space missions break new ground

Open cooperation, China Aerospace goes to the world

A staunch supporter of China's space undertakings

Scientists reviewed the research and development of Tianzhou cargo spacecraft

IRON AND ICE
DISH TV adding to fleet with new Maxar satellite order

European Space Agency chief eyes tapping private industry partners

Viasat confirms ViaSat-3 Americas set to launch

Sidus Space announces oricing of $10M Public Offering

IRON AND ICE
General Atomics completes commissioning of space environmental testing chambers

Confusion reigns over flash in skies above Kyiv

NASA's 3D-printed superalloy can take the heat

Momentus launches Vigoride-6 OSV on SpaceX Transporter-7 Mission

IRON AND ICE
TESS celebrates fifth year scanning the sky for new worlds

New stellar danger to planets identified by Chandra

International team discover new exoplanet partly using direct imaging

Webb peeks into the birthplaces of exoplanets

IRON AND ICE
Icy Moonquakes: Surface Shaking Could Trigger Landslides

Europe's Jupiter probe launched

Europe's JUICE mission blasts off towards Jupiter's icy moons

Spotlight on Ganymede, Juice's primary target

Subscribe Free To Our Daily Newsletters




The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.