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During a recent field trip to the icy plains of Antarctica, an international team of researchers discovered five new meteorites – including one of the largest ever found on the continent.
The rare meteorite is about the size of a cantaloupe, but weighs a whopping 7.7 kilograms. The specimen is one of only about 100 of this size or larger discovered in Antarctica, a prime meteorite hunting area where more than 45,000 space rocks have been tracked.
The extraordinary find is now going to the Royal Belgian Institute for Natural Sciences in Brussels, where it will be examined. And Maria Valdes, a research scientist at the Chicago Field Museum of Natural History and the University of Chicago who was part of the expedition team, saved some of the material for her own analysis.
Valdes’ area of focus is cosmochemistry. That “broadly means that we’re using meteorites to study the origin and evolution of the solar system through chemical methods,” she told CNN. She will take her samples and dissolve them with strong acids before using a process called calibrated chemistry to isolate different elements that make up the rock.
“Then I can start thinking about the origin of this rock, how it evolved over time, what type of mother body it came from, and where in the solar system that mother body formed,” Valdes said. “Those are the big questions we’re trying to answer.”
Meteorites hit the Earth evenly across its surface, so Antarctica isn’t home to a disproportionate concentration of them, Valdes written down. But the pure white ice is an ideal backdrop for watching the pitch-black rocks.
Hunting meteoroids is “really low-tech and less complicated than people might think,” Valdes said. “We either walk around or ride a snowmobile and look at the surface.”
But the team had an idea where to look. A January 2022 study used satellite data to narrow down the locations where most of the meteorites were located likely to find.
“Meteorites themselves are too small to detect from space with satellites,” Valdes explained. “But this study used satellite measurements of surface temperature, surface tilt, surface speed, ice thickness — things like that. And it put (the data) into a machine learning algorithm to tell us where the probability of finding meteor aggregation zones is greatest.”
Distinguishing a meteorite from other rocks can be a tricky process, Valdes said. Researchers are looking for melt crust, a glass-like coating that forms as the cosmic object plummets through Earth’s atmosphere.
“Many rocks look like meteorites but aren’t,” she said. “We call this meteorite failure.”
Another distinguishing feature is the weight of the potential specimen. A meteorite is much heavier for its size than a typical terrestrial rock because it is filled with dense metals.
The conditions the researchers faced were grueling. Although Valdes and three other scientists conducted their mission during the continent’s “summer,” which offered 24 hours of daylight, temperatures still fluctuated around 14 degrees Fahrenheit (minus 10 degrees Celsius), according to a press release from the field museum.
The research team spent about a week and a half with a polar field guide and lived in tents set up on the icy terrain. However, Valdes said she and her colleagues did too spent time at a Belgian research station near the coast of Antarctica, enjoying warm, cheesy dishes like fondue.
When it comes to future research, The good news, Valdes added, is that the five meteorites she and her colleagues discovered on this expedition are just the tip of the iceberg.
“I’m definitely looking forward to going back there,” she said. “Based on the satellite study, at least 300,000 meteorites are still waiting to be collected in Antarctica. And the larger the (number of) samples we have, the better we can understand our solar system.”
The excursion was led by Vinciane Debaille, Professor at the Université Libre de Bruxelles in Brussels. She and Valdes were joined by Maria Schönbächler, a professor at the Swiss Federal Institute of Technology in Zurich and a PhD student Ryoga Maeda from the Vrije Universiteit Brussel and the Université Libre de Bruxelles.