Meteorites—bits of space rock and iron that don’t completely burn up in our thick atmosphere—fall pretty uniformly across the surface of the Earth. The problem is lots of them just plunk into the ocean, and those over land are difficult to find, sometimes falling into humid jungles where they corrode or on rocky areas where they’re hard to spot. That’s why, since at least the 1970s, researchers have traveled to Antarctica to search for meteorites, where the little black rocks sit like pepper specks on top of the icy landscape.
About two-thirds of all meteorites scientists have found come from the southern continent, but researchers recently noticed something—over the years they’ve found far fewer iron meteorites from the icy domain than they would expect. That’s why the University of Manchester and British Antarctic Survey recently tested meteorite-hunting gear to try and find the missing chunks of iron.
And they came back with a big haul: The first all-British Antarctic meteorite hunt led by Katherine Joy of the University of Manchester, collected 36 space rocks, ranging in size from small melons to small flecks, after scouring unsearched areas of East Antarctica.
In other areas of the world, iron meteorites make up about 5 percent of all the space rocks found, Geoff Evatt, one of the project’s leaders and an applied mathematician at the University of Manchester, tells Jonathan Ames at the BBC. In Antarctica, that ratio is only 0.5 percent, meaning searchers are missing a huge haul of important meteorites.
Evatt and his team hypothesize that metal meteorites heat differently than the rocky meteorites, which more or less pop out of the ice when they warm up. The iron bits begin to rise toward the surface of the ice, but when they encounter sunlight they conduct more heat, melting the ice around them and slipping deeper into the ice, a theory they outlined in a 2016 paper in the journal Nature Communications. According to his calculations, Evatt believes that many of the iron chunks should be sitting about one foot under the ice.
“The whole notion of a layer of missing meteorites in Antarctica came out of blue-sky discussions at an interdisciplinary workshop, between a group of applied mathematicians and glaciologists, back in 2012,” Evatt says in a press release. “Having subsequently turned those initial ideas into firm scientific reasoning, we now have the opportunity to put our mathematical hypothesis to the most extreme of tests!”
Finding them shouldn’t be too hard, technologically. A simple metal detector could do the trick. The problem is covering the vast sub-zero expanse, where the team believes there is only one iron meteorite per 0.4 square miles or less.
That’s why between December 2018 and February 2019, the researchers experimented with new meteorite hunting gear, in the hopes of launching a full-scale expedition in 2020. Using a system similar to a modified landmine detector, the team can drag an array of metal detecting panels behind a snowmobile at 9 miles per hour. Evatt tested the system at an area of compressed blue ice called Sky-Blu in western Antarctica.
“In real-time, we’re able to sense what’s going on underneath the surface of the ice,” he tells Ames at the BBC. “And if an iron object passes under the panels then some lights and some audio equipment flashes up on the skidoo and we can then go out and hopefully retrieve the meteorite that’s within the ice.”
Robin George Andrews at The Atlantic reports that iron meteorites are of particular importance to those studying objects in space. So far, researchers have found iron space rocks coming from 100 different sources, including the interiors of planets and the cores of asteroids, revealing important data about different celestial bodies. “Any new meteorite we find could provide us with a previously unsampled asteroid type that tells us something new about how planets first formed and geologically evolve,” Joy says.
The gear will next go to the Arctic for further tweaking before being deployed for the full mission next year. While it would be awesome if during next year’s expedition the team could uncover lots of buried meteorites, Evatt says just discovering one hidden iron rock would make him happy, and could unlock entire new worlds of data.