On the night of 28 February a rocky shard fell from the sky and illuminated the atmosphere above England. The impressive fireball was captured by an international network of meteorite detection cameras, and scientists were sent to the sleepy town of Winchcombe. A piece of the meteorite was found on a driveway, while another was discovered in a field full of sheep manure.
About 18 ounces of space rock have been found so far, all of which were immediately delivered to a select few scientific institutions – the London Natural History Museum – for preliminary analysis. The rapid transport of the samples to the laboratories was crucial to ensure that the Earth’s environment did not change the chemistry of these almost pristine materials from space.
It appears that the meteorite – first found in the UK in 30 years – is a rather rare species known as a carbonaceous chondrite. These ancient fragments contain not only the building blocks of planets, but also compounds that can help explain how the earth got its water or even give clues as to how life itself began.
“It’s like the magical kind of meteorite that many people are completely fascinated by,” says Katherine Joy, a meteorite expert at the University of Manchester.
Oddly enough, at first glance, it does not appear that the chemistry, minerals and textures of the meteorite belong to any kind of carbonaceous chondrite. Each of the fragments studied so far appears to be slightly 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. This is an interesting possibility, but additional research is needed to say somehow.
The scientific work on what is likely to be known as the Winchcombe meteorite has just begun. But the scarcity of the meteorite, coupled with the speed with which it was recovered, caused the meteorite community to explode with cheers.
“We all just went bananas,” says Sara Russell, a planetary scientist at the London Natural History Museum. “For our meteorite group, this is the most important acquisition, I would say ever.”
Time capsules from above
Meteorites hit the 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 the collected meteorites occur in deserts, especially the cold desert of Antarctica, a vast expanse where the ice of conveyor belts in specific areas lies debris, and the white colors of the continent black meteorites easily stand out.
The UK is small, so meteorites do not hit the islands regularly, and it is full of cities and vegetation, which meteorites find difficult. But occasionally spatial rocks fall in front of people’s noses. On Christmas Eve 1964, a meteorite ‘jumped through 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 UK have improved their chances by setting up cameras designed to spy fireballs, which are used to find out where the fragments fall on the earth. Over the past decade, six different camera cameras, managed by both amateur and professional researchers, have been integrated into the UK Fireball Alliance.
These cameras “point to the sky all the time”, and always take recordings and look out for any striking flashes or objects streaking through the sky, says Jim Rowe, the group’s organizer. During the pandemic, he wrote computer code that ensures that these individual networks can communicate with each other to detect objects falling from above.
The system has occasionally captured fireballs over the past five years, but the impact sites have not been easy to collect. “A few years ago ‘there was a fireball that dropped a meteorite directly into the North Sea’, says Daly, and misses the surrounding countries of the UK, Northern Europe or Norway where it could be found.
Welcome to Winchcombe
At the end of February, after years of watching and waiting, a six-second fireball is caught throwing meteorite fragments over Gloucestershire, a country in the south-west of England. The track was immediately analyzed by a team of international researchers working with the UK Fireball Alliance, the potential impact zone was determined and experts from across England descended on the city of Winchcombe and the surrounding region.
After a few days of looking around, scientists informed the local press and asked the public to help them find strange rock fragments. People from across the country have sent countless photos of possible fragments to experts.
One family woke up to find black rock fragments and sooty splashes on their driveway. After hearing about reports of a fireball, they quickly discovered that the debris was meteorite, and they contacted the UK Meteor Observation Network. Only twelve hours after the impact, a large part of the meteorite had already been packed, ready to be picked up by experts.
“What a generous thing to realize how important it is to science and want to contribute to it,” says Joy.
Daly and his girlfriend Mira Ihasz joined a group sown through a nearby field of sheep dung. As a rock streaks through the earth’s atmosphere, material melts and then hardens into a black shell, and the dark colors of the sheep dung look uncomfortable like the scorched crust of meteorites.
“Another promising poop, as we started calling them,” Daly says. But after that five days of searching, Ihasz ran into the right case.
The piece was found within 1,300 feet of where the models said fragments should have landed – a remarkable degree of accuracy, but not accurate enough for the model workers, who, according to Daly, expressed disappointment that their prediction was no longer accurate.
‘A mudball from the start’
Preliminary work has determined that the meteorite was a carbonaceous chondrite: rocky objects as old as the solar system named after their carbon-rich compositions. Such space rock is rare. Of the 65,209 meteorites cataloged, only 2,639 are carbonaceous chondrites.
The exact origin of most meteorites remains a mystery. But thanks to the well-documented Earth orbit of the Winchcombe meteorite, it is traced back to the outer edge of the asteroid belt, between Mars and Jupiter.
“Knowing where this thing is coming 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 types of disturbances in space that can cause rocks to interfere.
Although the Winchcombe meteorite shows characteristics of several types of carbonaceous chondrites, meaning that it may be something completely new, the initial chemical analysis fixed it as a CM type. These meteorites contain (among other things) abundant aqueous minerals.
“It’s been a mud ball from the start,” said 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,’ “says Daly. The minerals inside weaken rapidly in the earth’s wet atmosphere, and when exposed to the elements for a long time, these things only turn to dust.
“The fact that it was so fragile and delicate, and the fact that it was collected so quickly, was critical,” Joy says. “This was packed back into the museum within 36 hours, 48 hours after it fell, which just doesn’t happen often.” The rapid recovery means that its ingredients are almost perfectly preserved – and they have enough to reveal about the early solar system and the lush planet we live on today.
Secrets of the earth and space
One secret hidden in rocks like the Winchcombe meteorite has to do with how the earth got such large amounts of water. The huge impact on our planet that led to the formation of the moon about 4.5 billion years ago probably removed much of the water that the earth started with.
Whether the surface water we have today came mostly from within the planet and escaped by volcanic eruptions, and whether it was mainly supplied by wet asteroids is a matter of debate. By studying the hydrated minerals in carbonaceous chondrites, Russell says, we can discover what process has filled the oceans of our modern world.
CM chondrites generally also contain many different organic molecules, including amino acids and sugars, and this meteorite is not expected to be any different. Asteroids that bombed the early Earth would have brought together this organic material, and perhaps deposited the material formed for the first living organisms.
“The fact that organic chemistry may have accelerated the origin of life on earth,” says Genge.
Meteorites can also tell us about the time before the earth came into being. The Winchcombe meteorite contains features known as calcium-aluminum-rich inclusions, or CAIs. “It’s the oldest solid in the solar system, which is obviously the most amazing thing,” Russell says.
The chemistry of CAIs suggests that they all formed 4.56 billion years ago at the same time and place, right next to the sun, before being trapped in rocky material that collapsed in the cold recesses of the outer solar system. The dramatic, outward journey of this material is not easy to explain, but collecting more CAIs will help unravel how matter moves and mixes as planets formed and the solar system evolved into its modern form.
CM chondrites also often contain substances such as graphite and diamond grains that, remarkably, are older than the solar system itself. Their chemistry is so different from everything that occurs in our solar system, that scientists believe they came from the atmosphere of giant stars or formed into supernova explosions before drifting to our ever-evolving cosmic environment.
Such grains were ‘blown out into the universe, floated around for hundreds of millions of years and then collapsed inside to form our solar system’, says Genge. Although these jewels have not yet been identified in the Winchcombe meteorite, scientists expect them to contain, like other CM chondrites, grains that predate the solar system.
So the Winchcombe meteorite could not only contain clues to the history of our environment around the sun, but also the ghosts of other planetary systems that have lost time – and the international effort to decode its many secrets has just begun.