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On the night of February 28, a rock shard fell from the sky and illuminated the atmosphere over England. The impressive fireball was captured by an international network of meteorite tracking cameras and scientists were dispatched to the sleepy town of Winchcombe. A piece of meteorite was found on an alley, while another was discovered in a field filled with sheep droppings.
About 18 ounces of space rock have been found so far, all of which were quickly delivered to a few select scientific institutions – primarily the Natural History Museum in London – for preliminary analysis. The rapid transport of samples to laboratories was essential to ensure that the Earth’s environment did not significantly alter the chemistry of these nearly intact materials from space.
It turns out that the meteorite – the first discovery in the UK in 30 years – is a rather rare type known as carbonaceous chondrite. These ancient fragments not only contain the building blocks of the planets, but also compounds that can help explain how the Earth got its water or even provide clues as to how life itself began.
“It’s like the magical type of meteorite that fascinates a lot of people,” says Katherine Joy, a meteorite expert at the University of Manchester.
Strangely, at first glance, the meteorite’s chemistry, minerals, and textures do not appear to belong to any type of carbonaceous chondrite. Each of the fragments studied so far seems to be a little different from the others.
“Could this be a new type of meteorite, a new class of meteorite, something that we have never seen before?” asks Luke Daly, a meteorite expert at the University of Glasgow. It’s an intriguing possibility, but more research is needed to tell one way or another.
Scientific work on what will likely become the Winchcombe meteorite is just beginning. But the meteorite’s rarity, combined with the speed with which it was recovered, blew up the meteorite community with glee.
“We’ve all just switched to bananas,” says Sara Russell, planet specialist at the Natural History Museum in London. “For our meteorite group, this is the most important acquisition, I would say, ever.”
Time capsules from above
Meteorites crash into Earth all the time, but most are not large enough to announce themselves with a fireball. Even when they do, many fall into the oceans. The vast majority of meteorites collected are found in deserts, especially the cold Antarctic desert, a huge expanse where conveyor belt-shaped ice flows deposit space debris in specific areas, and the continent’s white hues. allow black meteorites to stand out easily.
The UK is small, so meteorites don’t hit islands often, and it’s full of towns and vegetation, making meteorites hard to find. But sometimes space rocks accidentally fall right in front of people’s noses. On Christmas Eve 1964, a meteorite “bounced off an alley, 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 UK have improved their chances by installing cameras designed to spy on fireballs, which are used to determine where the fragments fall on Earth. Over the past decade, six different sky-facing camera arrays, managed by amateur and professional researchers, have been integrated into the UK Fireball Alliance.
These cameras “point the sky all the time,” always recording, looking for noticeable flashes or objects crossing the sky, explains Jim Rowe, the group’s organizer. During the pandemic, he wrote computer code that allowed these individual networks to communicate with each other to track any object falling from above.
The system has captured occasional fireballs for 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 UK, northern Europe or Norway where it could have been recovered.
Welcome to Winchcombe
In late February, after years of watching and waiting, a six-second fireball was caught hurling meteorite fragments across Gloucestershire, a county in southwest England. The trajectory was immediately analyzed by a team of international researchers working with the UK Fireball Alliance, the likely impact area was determined and experts from across England descended on the town of Winchcombe and the surrounding area.
After a few days of research, the scientists alerted the local press and asked the public to help them find the strange rock fragments. People from across the country have sent the experts countless photographs of possible fragments.
A family woke up to find black rock shards and soot-like splatters on their driveway. After hearing about a fireball, they quickly realized that the debris was meteorite and contacted the UK Meteor Observation Network. Barely 12 hours after impact, much of the meteorite had already been packed, ready to be collected by experts.
“What a generous thing, to recognize how important it is to science and to want to contribute to it,” Joy says.
Daly and his girlfriend Mira Ihasz joined a group rummaging in a nearby field riddled with sheep droppings. As a rock passes through Earth’s atmosphere, the material melts and then hardens into a black shell, and the dark hues of the sheep dung resembled the burnt crust of meteorites.
“Another promising poo, as we’ve started to call them,” Daly says. But after five days of research, Ihasz stumbled upon the real deal.
The piece was found within 1,300 feet of where the models said the fragments should have landed – a remarkable degree of precision, but not precise enough for the modelers, who Daly said expressed some disappointment that their prediction was not more precise.
‘A ball of mud from the start’
Preliminary work determined that the meteorite was a carbonaceous chondrite: rocky objects as old as the solar system that are named after their carbon-rich compositions. Such space rocks are rare. Of the 65,209 meteorites listed, only 2,639 are carbonaceous chondrites.
The precise origins of most meteorites remain a mystery. But thanks to the well-documented Earth track of the Winchcombe meteorite, it has been traced to the outer edge of the asteroid belt, between Mars and Jupiter.
“Knowing where this thing came from and what it is about is very special,” says Joy. This knowledge makes it easier to determine the type of asteroid the meteorite broke off from, and also helps scientists better understand the types of disturbances in space that can send rocks rushing our way.
Although the Winchcombe meteorite exhibits characteristics of several types of carbonaceous chondrites, which means it could be something entirely new, initial chemical analysis established it as a CM type. These meteorites contain (among other things) many minerals that contain water.
“It’s been a ball of mud from the start,” says Genge of Imperial College London. Only 652 of them have been found.
Compared to most other types of meteorites, CM chondrites “are incredibly delicate,” Daly says. The minerals inside degrade quickly in Earth’s humid atmosphere, so if left exposed to the elements for a long time, “these things turn to dust.”
“The fact that it was so fragile and delicate, and the fact that it was collected so quickly, was critical,” says Joy. “This one was packaged and returned to the museum within 36, 48 hours of drop, which doesn’t happen very often.” Rapid recovery means its ingredients have been almost perfectly preserved – and they will have a lot to reveal about the early solar system and the lush planet we live on today.
Secrets of Earth and Space
A secret hidden in rocks like the Winchcombe meteorite has to do with how the Earth got such amounts of water. The giant impact on our planet that led to the formation of the moon about 4.5 billion years ago has likely stripped much of the water the Earth started with.
Whether the surface water we have today is primarily from the planet and escaped as a result of volcanic eruptions, or if it was primarily supplied by soggy asteroids is a matter of debate. . By studying the hydrated minerals in carbonaceous chondrites, says Russell, we can find out what process has filled the oceans of our modern world.
CM chondrites also typically contain many different organic molecules, including amino acids and sugars, and this meteorite shouldn’t be any different. The asteroids bombarding early Earth would have brought this organic matter with them, possibly depositing the materials necessary for the formation of the first living organisms.
“This organic chemistry may well have accelerated the origins of life on Earth,” says Genge.
Meteorites can also tell us about the time before Earth formed. The Winchcombe meteorite contains features known as calcium-aluminum rich inclusions or CAIs. “These are the oldest solids in the solar system, which of course is the most amazing and cool thing,” says Russell.
The chemistry of the IACs suggests that they all formed at the same time and in the same place, 4.56 billion years ago, right next to the sun, before getting stuck in a rocky material that clumped in the cold recesses of the outer solar system. The dramatic, outward journey of this material isn’t easy to explain, but collecting more CAI will help understand how matter moved and mixed together as the planets formed and the solar system evolved into its form. modern.
CM chondrites also often contain substances like graphite and diamond grains which are remarkably older than the solar system itself. Their chemistry is so distinct from anything in our solar system that scientists believe they originated from the atmospheres of giant stars or formed in supernova explosions before drifting into our still-forming cosmic neighborhood.
These grains were “blown out into the universe, floating for hundreds of millions of years, then collapsing inward to form our solar system,” says Genge. While these primordial gems have yet to be identified in the Winchcombe meteorite, scientists expect it, like other CM chondrites, to contain grains that predate the solar system.
The Winchcombe meteorite could therefore contain not only clues to the history of our neighborhood around the sun, but also the ghosts of other planetary systems lost in time – and the international effort to decode its many secrets is only just beginning.
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