If you’re looking for meteorites, here’s a tip: Go south. All the way south. And do it soon.
In some parts of Antarctica, there’s a good chance that what looks like a regular old rock could actually be a chunk of an asteroid, the moon, or even Mars. Roughly 60 percent of all known meteorites have been collected there.
But scientific sleuthing for such extraterrestrial material, which can shed light on how the solar system formed billions of years ago, will probably get more difficult in Antarctica in the coming decades. That’s because, as temperatures rise, thousands of meteorites will sink into the continent’s ice and disappear from sight every year, according to a new study published on Monday.
Antarctica’s meteorite largess isn’t because more extraterrestrial stuff is falling there, Cari Corrigan, a geologist at the Smithsonian Institution and a curator of the National Museum of Natural History’s meteorite collection, said.
Rather, meteorites simply tend to be more visible on the Antarctic ice sheet than they would be, say, in your backyard. “Your eye can pick out a dark rock on a white surface super easily,” said Dr. Corrigan, who was not involved in the new research.
The continent also has places known as blue-ice areas, that are particularly good for finding meteorites. These regions are often near geographic obstructions like mountains, where layers of ice tend to pile up and strong winds continuously erode the surface. Those conditions are ideal for concentrating, and revealing, meteorites that have fallen over millenniums.
But warming temperatures could send many meteorites out of sight. In recent years, researchers have spotted specimens in Antarctica that have been partially encrusted in ice rather than sitting exposed on the surface.
The meteorites, most of which have dark surfaces, are heating up more and melting the ice underneath them, said Veronica Tollenaar, one of the lead authors of the paper, which was published in the journal Nature Climate Change.
“The meteorite will sink,” said Ms. Tollenaar, a doctoral candidate in glaciology at the Université Libre de Bruxelles in Belgium. And as temperatures continue to rise, that melting process is only likely to intensify, she and her colleagues suggested.
Using a model they developed, the team estimated the number of meteorites that would be visible in Antarctica’s blue-ice areas under different warming scenarios. The researchers found that anywhere from 4,000 to 6,000 meteorites will disappear from sight each year over the next few decades. By the end of the century, up to three-quarters of Antarctica’s meteorites that once sat exposed on the ice could be hidden from view, the team estimated.
Meteorites rich in metals like iron are probably at the highest risk of being lost, said Harry Zekollari, a glaciologist at ETH Zurich in Switzerland and at the Vrije Universiteit Brussel in Belgium, who led the research along with Ms. Tollenaar. That’s because iron-rich meteorites are good at conducting heat. “They may be able to more easily transfer their heat to the surrounding ice,” Dr. Zekollari said.
That’s supported by a study published in 2016 that showed that iron meteorites are underrepresented in samples from Antarctica.
Future expeditions to Antarctica to find meteorites should prioritize sites at lower elevations, Ms. Tollenaar said. Those places, which tend to be warmer, are where meteorites are most likely to disappear in the coming years.
Most meteorite-rich places in Antarctica are at elevations between 5,900 and 6,600 feet. But nearly nine out of 10 meteorites at those elevations will sink out of view by the end of the 21st century, the team calculated. “It’s important to focus efforts on the most sensitive areas,” Ms. Tollenaar said.
Dr. Corrigan, who has made two trips to Antarctica to search for meteorites, acknowledged the urgency. “We’d like to get out there and get as many of these as we can before they disappear.”
Technology might be able to help, according to Dr. Zekollari. Most meteorites in Antarctica are found the old-fashioned way: by networks of people traveling on foot or on snowmobiles, he said. But efforts are underway to use technology like drones to scan the ice.
“We need to be more efficient,” Dr. Zekollari said. “It’s a race against the clock.”
Source link: https://www.nytimes.com/2024/04/08/climate/meteorites-antarctica.html