Scientists have detected trace amounts of superconducting material inside one of the world’s largest meteorites, according to a new study.
Superconductors are materials that can conduct electrical current without resistance, and they’re coveted by researchers who study quantum computers and companies hoping to transfer energy more efficiently. The superconductor inside the Australian meteorite is a known material, but the discovery itself comes as a shock.
“The big takeaway is that there is superconductivity in the sky, naturally occurring,” Ivan Schuller, one of the study’s lead authors from the University of California, San Diego, told Gizmodo.
Schuller’s team isn’t just interested in meteorites – they’re looking for superconductivity everywhere. Six years ago, his team debuted a technique called magnetic field modulated microwave spectroscopy (MFMMS). The MFMMS method starts with scientists putting tiny sample fragments into a cavity filled with microwaves and an oscillating magnetic field and then cooling it. When samples transition from conductors to superconductors, the way they absorb microwaves dramatically changes. The MFMMS method allows scientists to quickly scan through lots of materials to determine whether or not they are superconductors.
And that’s exactly what the researchers were doing here; they were using a grant from the United States Air Force to hunt for superconductivity in whatever materials they could test. Given the extreme environments in which extraterrestrial materials could form, meteorites were a logical place to search.
The team scanned through hundreds of meteorite samples: first microscopic meteorites and then larger fragments. Graduate student James Wampler finally measured the superconducting transition in two meteorite fragments: one from the Mundrabilla meteorite, one of the world’s largest meteorites comprising 22 metric tons of pieces scattered across Australia’s Nullarbor plains, and one from a meteorite called GRA 95205. The superconducting material was an alloy of indium, lead, and tin, a material previously known as a superconductor to scientists. It’s the first evidence of superconductivity in space.
This discovery was no glamorous “eureka” moment. Given that the superconductor was a material already known on Earth, the scientists immediately wondered whether they’d accidentally contaminated the samples.
“I don’t remember the moment when I found it,” Wampler told Gizmodo. “Your first reaction is that it’s faking you out, it’s something else. It’s very cynical, not in a bad way, but being cynical makes you double check yourself.”
The team brought their samples to scientists Yimei Zhu and Shaobo Cheng at Brookhaven National Lab to inspect them using electron microscopes. Only after that confirmation could they feel confident they’d actually discovered a naturally occurring superconductor from space. Wampler first presented his results at the March meeting of the American Physical Society in 2018, and the team published their peer-reviewed paper in the Proceedings of the National Academy of Sciences today.
Munir Humayun, a professor at Florida State University who reviewed the study, thought that it was a very interesting one. He said the authors did a good job ruling out obvious sources of contamination but still found it disconcerting that we know this alloy exists in synthetic forms on Earth. “The problem with non-obvious sources of contamination is that they aren’t obvious,” he told Gizmodo.
Still, “this paper is one of the shocking papers that makes you go, whoa, we need to look at things we weren’t looking at before,” Humayun said. “This paper opens the door on an entire field of inquiry to look at rare metals like these indium-tin-lead alloys not known from meteorites previously.”
It’s hard to say how exactly this alloy forms in space. These meteorites’ components would have undergone chemical changes like heating and recrystallisation during solar system formation, obscuring the environment their materials first formed in. While this alloy isn’t a superconductor at room temperature on Earth, there are locations of space colder than the 5 degrees Kelvin at which it becomes a superconductor. Plus, the kind of material in the GRA 95205 meteorite demonstrates it formed in extreme conditions that might have formed other superconducting materials as well.
If these alloys took on superconducting properties in the cold of space, perhaps they could affect the magnetic fields surrounding them, producing phenomena potentially visible to telescopes on Earth. But these hypotheses will require a lot more evidence, modelling, and research before they hold any water.
For Schuller’s team, the discovery of a material already known on Earth doesn’t aid in their quest for new superconductors. As such, they plan to continue using the MFMMS method to scan through other samples that might hold exciting new materials.
Featured image: Graeme Churchard (Wikimedia Commons)