Newfound meteorite could help unlock secrets of the solar system
On the night of February 28, a rocky shard fell from the sky and lit up the atmosphere above England. The impressive fireball was caught by an international network of meteorite-tracking cameras, and scientists were dispatched to the sleepy town of Winchcombe. A chunk of the meteorite was found on a driveway, while another was discovered in a field full of sheep droppings.
About 18 ounces of space rock have been found so far, all of which was promptly delivered to a select few scientific institutions—chiefly London’s Natural History Museum—for preliminary analysis. Speedily transporting the samples to the laboratories was crucial to ensuring that Earth’s environment didn’t significantly alter the chemistry of these near-pristine materials from space.
It turns out that the meteorite—the first found in the United Kingdom in 30 years—is a rather rare type known as a carbonaceous chondrite. These ancient fragments contain not only the building blocks of planets, but also compounds that may help explain how Earth got its water or even provide clues for how life itself got started.
“This is like the magic type of meteorite that lots of people are completely fascinated by,” says Katherine Joy, a meteorite expert at the University of Manchester.
Strangely, at first glance, the chemistry, minerals, and textures of the meteorite don’t seem to belong to any one type of carbonaceous chondrite. Each of the fragments studied so far appears to be a little different from the others.
“Could it be a new meteorite type, a new meteorite class, something we’ve never seen before?” asks Luke Daly, a meteorite expert at the University of Glasgow. It’s an intriguing possibility, but additional research is needed to say one way or the other.
The scientific work on what will likely become known as the Winchcombe meteorite has only just begun. But the rarity of the meteorite, combined with the speed with which it was recovered, has caused the meteorite community to explode with jubilation.
“We’ve all just gone bananas,” says Sara Russell, a planetary scientist at London’s Natural History Museum. “For our meteorite group, it’s the most important acquisition, I would say, ever.”
Time capsules from above
Meteorites smash into Earth all the time, but most are not big enough to announce themselves with a fireball. Even when they do, many tumble into the oceans. The vast majority of collected meteorites are found in deserts, particularly the cold desert of Antarctica, a huge expanse where conveyor belt-like ice flows deposit space debris in specific areas, and the continent’s white hues allow black meteorites to easily stand out.
The United Kingdom is small, so meteorites don’t strike the islands often, and it is full of cities and vegetation, making meteorites difficult to find. But occasionally space rocks serendipitously fall right in front of people’s noses. On Christmas Eve 1964 a meteorite “bounced off a driveway, through someone’s window, and landed under their Christmas tree,” says Matthew Genge, a meteorite expert at Imperial College London.
In recent years, meteorite hunters in the U.K. have improved their odds by setting up cameras designed to spy fireballs, which are used to work out where the fragments fall to Earth. Over the past decade, six different networks of sky-facing cameras, run by both amateur and professional researchers, have been integrated into the U.K. Fireball Alliance.
These cameras “are pointing at the sky the whole time,” always recording, looking out for any notable flashes or objects streaking through the sky, says Jim Rowe, the group’s organizer. During the pandemic, he wrote computer code that ensured these individual networks could communicate with each other to track any objects falling from above.
The system has captured occasional fireballs over the past five years or so, but the impact sites were not convenient for collection. A few years ago, “there was a fireball that dropped a meteorite directly into the North Sea,” Daly says, missing the surrounding lands of the U.K., northern Europe, or Norway where it could have been recovered.
Welcome to Winchcombe
At the end of February, after years of watching and waiting, a six-second fireball was caught throwing meteorite fragments across Gloucestershire, a county in southwest England. The trajectory was immediately analyzed by a team of international researchers working with the U.K. Fireball Alliance, the likely impact zone was determined, and experts from across England descended upon the town of Winchcombe and the surrounding region.
After a few days of looking around, scientists notified the local press and asked the public to help them find any odd-looking rock fragments. People from across the country sent experts countless photographs of possible fragments.
One family awoke to find black rock fragments and soot-like spatter on their driveway. After hearing about reports of a fireball, they quickly figured out the debris was meteoritic, and they contacted the U.K. Meteor Observation Network. Just 12 hours after impact, a large chunk of the meteorite had already been bagged up, ready to be collected by the experts.
“What a generous thing, to recognize how important this is for science and want to contribute to that,” Joy says.
Daly and his girlfriend Mira Ihasz joined a group combing through a nearby field riddled with sheep droppings. As a rock streaks through Earth’s atmosphere, material melts and then hardens into a black shell, and the dark hues of the sheep dung inconveniently resembled the scorched crust of meteorites.
“Another promising poo, as we started to call them,” Daly says. But after five days of searching, Ihasz stumbled upon the real deal.
The chunk was found within 1,300 feet of where the models said fragments should have landed—a remarkable degree of accuracy, but not precise enough for the modelers, who according to Daly expressed some disappointment that their prediction was not more accurate.
‘A mud ball from the beginning’
Preliminary work determined that the meteorite was a carbonaceous chondrite: rocky objects as old as the solar system that are named for their carbon-rich compositions. Such space rocks are rare. Out of the 65,209 meteorites catalogued, just 2,639 are carbonaceous chondrites.
Most meteorites’ precise origins remain a mystery. But thanks to the Winchcombe meteorite’s well-documented Earthbound trajectory, it was traced back to the outer rim of asteroid belt, between Mars and Jupiter.
“Knowing where this thing came from, and what it is, is very special,” Joy says. This knowledge makes it easier to work out what type of asteroid the meteorite broke away from, and it also helps scientists better understand the sorts of disturbances in space that can send rocks hurtling our way.
Although the Winchcombe meteorite shows characteristics of multiple types of carbonaceous chondrites, which means this could be something entirely novel, the initial chemical analysis pegged it as a CM-type. These meteorites contain (among other things) abundant water-containing minerals.
“It’s a mud ball from the beginning,” says Genge of Imperial College London. Only 652 of them have ever been found.
Compared to most other types of meteorites, CM chondrites “are incredibly delicate,” Daly says. The minerals inside degrade quickly in Earth’s wet atmosphere, so if left exposed to the elements for long, “these things just turn to dust.”
“The fact that it is so fragile and delicate, and the fact that it was collected so quickly, was critical,” Joy says. “This one was bagged and back at the museum within 36, 48 hours of it falling, which just doesn’t happen very often.” The quick recovery means its ingredients have been nearly perfectly preserved—and they will have plenty to reveal about the early solar system and the lush planet we live on today.
Secrets of Earth and space
One secret hidden in rocks like the Winchcombe meteorite has to do with how Earth got such vast quantities of water. The giant impact with our planet that led to the formation of the moon some 4.5 billion years ago likely stripped away much of the water that Earth started with.
Whether the surface water we have today mostly came from within the planet and escaped through volcanic eruptions, or whether it was primarily delivered by soggy asteroids is a matter of debate. By studying the hydrated minerals in carbonaceous chondrites, Russell says, we may discover which process filled the oceans of our modern world.
CM chondrites also generally contain many different organic molecules, including amino acids and sugars, and this meteorite is expected to be no different. Asteroids bombarding the early Earth would have brought this organic matter with them, perhaps depositing the materials needed for the first living organisms to form.
“That organic chemistry may well have accelerated the origins of life on Earth,” Genge says.
Meteorites can also tell us about the time before Earth formed. The Winchcombe meteorite contains features known as calcium-aluminum-rich inclusions, or CAIs. “They’re the oldest solids in the solar system, which of course is the most amazing, cool thing,” Russell says.
The chemistry of CAIs suggests they all formed at the same time and place, 4.56 billion years ago, right next to the sun, before ending up wedged in rocky material that clumped together in the cold recesses of the outer solar system. The dramatic, outward journey of this material isn’t easy to explain, but gathering more CAIs will help unravel how matter moved and mixed as planets were forming and the solar system was evolving to its modern form.
CM chondrites also often contain substances like graphite and diamond grains that are, rather remarkably, older than solar system itself. Their chemistry is so distinct from anything found within our solar system that scientists believe they came from the atmospheres of giant stars or formed in supernovae explosions before drifting to our still-forming cosmic neighborhood.
Such grains were “blown out into the universe, floating around for hundreds of millions of years, and then collapsing inwards to form our solar system,” Genge says. While these primordial gems have not yet been identified in the Winchcombe meteorite, scientists fully expect that, like other CM chondrites, it contains grains that pre-date the solar system.
The Winchcombe meteorite could therefore hold not only clues to the history of our neighborhood around the sun, but also the ghosts of other planetary systems lost to time—and the international effort to decode its many secrets has only just begun.