Black Beauty, or NWA 7034, is believed to have actually formed at a time when the Red Planet harbored an electromagnetic field, much like the Earth does today. If the rock bears any trace of Mars ancient field, this might provide researchers valuable clues to the worlds past environment and structure. Credit: C Agee, Institute of Meteoritics, UNM; NASA
A new research study reveals that easy hand magnets erase a meteorites magnetic memory.
A new MIT research study exposes that hand magnets, commonly used by meteorite hunters and collectors to confirm meteorites identities, frequently eliminate the rocks magnetic memory, thus ruining important clinical data. The researchers discovered that hand magnets reorient the tiny grains within the rocks, eliminating traces of their magnetic origins. The team has analyzed multiple samples of a meteorite known as Northwest Africa (NWA) 7034 or “Black Beauty,” only to find that all samples have actually been remagnetized because landing in the world. To avoid additional destruction of magnetic records, the scientists recommend utilizing susceptibility meters instead of hand magnets, regardless of the higher cost.
Each year, thousands of space rocks pierce through the Earths atmosphere and hit the ground as meteorites. These fragments of comets and asteroids can land anywhere however are usually spotted in open surface, such as the deserts of Africa and the Antarctic blue ice, where a meteorites blackened outside can stand apart.
A brand-new MIT research study reveals that hand magnets, typically utilized by meteorite hunters and collectors to verify meteorites identities, often eliminate the rocks magnetic memory, therefore destroying valuable scientific information. 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 incredibly high magnetic field. Only later on did they realize that hand magnets were to blame for the meteorites strangely enough strong pull.
He later on found, much to his disappointment, that the meteorite had been reset by hand magnets.
Still, these extraterrestrial residues can resemble Earth rocks, and to discriminate meteorite hunters typically expose their “finds” to hand magnets, which can attract more strongly to metal-rich meteorites than to terrestrial rocks. Meteorite hunters, curators, dealerships, and collectors frequently depend on hand magnets to validate a meteorites identity.
However a new MIT study discovers that the very same magnets used to recognize a meteorite usually erase its magnetic memory. They show that direct exposure to a magnet can reorient a rocks microscopic grains, undoing their original orientation and any trace of its magnetic origins.
The scientists make their case with Northwest Africa (NWA) 7034, a meteorite understood in collectors circles as “Black Beauty” for its obsidian exterior. Numerous fragments of the meteorite were first discovered in the deserts of northwest Africa, and researchers determined that the rock included crystals that formed on Mars more than 4.4 billion years ago.
Black Beauty is believed to have actually 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 might give scientists valuable ideas to the planets past environment and composition.
Sadly, the MIT team found that multiple samples of Black Beauty have been remagnetized considering that landing in the world, which any tip of an ancient Martian field has been wiped tidy.
” There was an extraordinary record there, and an unique chance to understand the early history of Mars magnetism,” says study author Benjamin Weiss, teacher of planetary sciences at MIT. “But we discovered its all been eliminated by magnets.”
With their new research study, published on April 6 in the Journal of Geophysical Research: Planets, the scientists intend to raise awareness in the planetary science community about the devastating effects of hand magnets. Weiss co-authors are MIT postdoc Foteini Vervelidou and France Lagroix of the Paris Institute of Planetary Physics.
Dead ends
10s of thousands of meteorites have actually been discovered to date. Almost every discovered meteorite has actually been traced to about 100 parent bodies across the planetary system, consisting of asteroids, the moon, and Mars. Researchers trying to check out the history of these rocks have actually just recently pertained to realize that some analyses were way off the mark, due to the impact of hand magnets.
For example, samples of Allende, the biggest and most studied meteorite on Earth, bear traces of exposure to a strong electromagnetic field. Researchers assumed this field was proof that the meteorite formed long earlier in a solar nebula that hosted a very high magnetic field. Just later on did they understand that hand magnets were to blame for the meteorites curiously strong pull.
Weiss has also been fooled by artificially reset rocks. When he initially joined the MIT professors, he found signs of strong magnetism in fallen samples of an asteroid. The findings would have been the very first evidence that asteroids can distinguish and form metal cores like the Earth. He later found, much to his disappointment, that the meteorite had been reset by hand magnets.
” Theres a long history of dead ends and confusion over remagnetized rocks,” Weiss says.
For the MIT team, the tipping point featured NWA 7034. In 2014, fellow paleomagnetist Jérôme Gattacceca measured a sample of Black Beauty and discovered its initial magnetism, which was set more than 4.4 billion years back, had actually been entirely reversed by much stronger hand magnets on Earth. Weiss and Vervelidou just recently examined various other samples of Black Beauty, wishing to discover a minimum of one magnetically maintained sample.
” Our initial hope was that by testing as many [samples] of this meteorite as possible, we would end up finding a couple of non-remagnetized ones,” Vervelidou states. “Once we concluded that all of the samples we studied have been remagnetized, the inspiration was to spread out the word about the devastating impacts of hand magnets.”
Moving a field
In their brand-new study, the group laid out the methods in which hand magnets can affect a rocks natural magnetism. They initially established a numerical design, based on the physics of magnetism, to calculate the field surrounding a typical hand magnet and how it affects rocks of numerous sizes.
They then brought out experiments, exposing samples of the same terrestrial rock to magnetic fields of varying strengths and at different distances, and measured how each samples inherent magnetism altered in action. These measurements matched the designs predictions, revealing that the design can be used to determine whether a rock has been remagnetized. The model can also be utilized to approximate, based on a rocks magnetization, the depth at which a rock may still be unaffected.
Lastly, the team reported their measurements of 9 Black Beauty samples and confirmed with their model that every discovered piece of the meteorite had undoubtedly been exposed to hand magnets.
” What we have in this paper is lastly a clear, unambiguous work plan for developing whether your rock has actually been hit by a magnet,” Weiss says.
Rather of hand magnets, the researchers are advising that meteorite hunters, collectors, and museum managers use vulnerability meters– handheld instruments that have been shown to rapidly and precisely identify a meteorite without rushing its magnetic memory.
Weiss acknowledges that vulnerability meters are a hard sell– commercial models deserve a number of thousand dollars, compared to some hand magnets that cost next to absolutely nothing. Within the meteorite trade, he hopes first to encourage people upstream, such as museum managers and collectors. From there, word might drip down to those making discoveries on the ground.
” Theres been this incredible explosion of meteorite variety and number in the last 20 years approximately, and we owe meteorite hunters a thanks for finding these things,” Weiss states. “But the tradeoff, the devils deal, is that frequently they are utilizing magnets to find them, and are immediately ruining their magnetic record while doing so.”
Referral: “Hand Magnets and the Destruction of Ancient Meteorite Magnetism” by Foteini Vervelidou, Benjamin P. Weiss and France Lagroix, 6 April 2023, Journal of Geophysical Research: Planets.DOI: 10.1029/ 2022JE007464.
This research was moneyed, in part, by the European Unions Horizon 2020 research and innovation program.