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Pristine ‘Witness’ from Deep Space Sheds Light on the Origin of Life

On the night of February 28, 2021, a space rock slammed into Earth’s atmosphere and lit up the skies above the picturesque town of Winchcombe in the United Kingdom. The fireball was witnessed by more than a thousand people and was captured by numerous doorbell and dashboard cameras, sparking a social media frenzy that resulted in a hasty search for the remains of the extraterrestrial visitor. 

Within hours, about 300 grams of the so-called Winchcombe meteorite were found scattered across a local driveway and another 200 grams were recovered over the next week, including an intact chunk found on farmland.  

After more than a year of studying these otherworldly fragments, which originated in an ancient asteroid, scientists have concluded that the Winchcombe meteorite is “a unique and pristine witness from the outer solar system” that “is largely unmodified by the terrestrial environment” thanks to the rapid recovery of its parts, according to a study published on Wednesday in Science Advances.

The meteorite, which belongs to a group of space rocks called CM chondrites, is so unsullied by earthly conditions that it is comparable to samples snatched directly from the surfaces of asteroids by space probes. This pure primordial rock reveals unprecedented insights into the role asteroids played in delivering water and organic compounds to Earth billions of years ago, which has implications for understanding how life first arose on Earth, and whether it might exist elsewhere.

“Life as we know it needs two key things to have a chance at emerging: water and organic molecules—the Winchcombe meteorite has both,” said Luke Daly, a planetary geoscientist who co-authored the study, in an email to Motherboard, adding that “Winchcombe and other CMs are essentially a one-stop shop for everything a growing planet needs if it has ambitions of developing life.”

“The Earth, because of where it formed in our solar system, should have formed dry, so we need an extraterrestrial delivery service for water and organics to get our Blue planet but what is that water source?” he continued. “Winchcombe is the best evidence so far that CMs likely were a key source of water for Earth as the water in it is quite close in composition to that of the Earth as well as being rich in organics and because it was recovered so fast, we know it hasn’t been changed by its time on Earth.”

Daly and his colleagues, including lead author Ashley King of the National History Museum in London, got word of the meteorite almost instantly as people posted footage of the fireball on social media. Members of the team swiftly joined the search for fragments that was coordinated by the UK Fireball Alliance (UKFAll), an organization devoted to recovering freshly fallen space rocks in the nation.

“The next day we woke up to an inbox full of the best emails from our colleagues saying there are likely meteorites on the ground,” Daly recalled. “I genuinely couldn’t believe it when the driveway fragment was found and was even more gobsmacked when my partner found another piece while we were searching for it. I didn’t have any good words then and still don’t really have them now for that feeling of realizing that over five years of work from everyone in UKFAll had paid off in such a spectacular fashion!”

The voluminous footage of the fireball distinguishes it as “the most accurately recorded carbonaceous chondrite fall” in history, according to the study. In addition to this visual evidence, Daly and his colleagues have painstakingly examined select meteorite fragments using a host of sophisticated techniques, which has revealed amazing details about its backstory.

For instance, the researchers estimate that the meteorite was once part of a primitive asteroid that formed in the outer solar system but eventually ended up in the main belt located roughly between the orbits of Mars and Jupiter. 

An analysis of the rock’s exposure to cosmic rays suggests that it split off from its parent asteroid relatively recently, and that it has only been hanging around in near-Earth space for a maximum of 80,000 years, whereas most CMs are over two million years old. This asteroid chunk was likely small, weighing about 28 pounds, which would normally result in no surviving traces.

“We knew it had potential to contain some really cool stuff we don’t normally see, but what really cinched it I think was when we got the first data on the fireball back and realized that it had no right to have survived coming through our atmosphere, and just how lucky we were to have any meteorites on the ground at all,” Daly said. “It was only originally about the size of a basketball and if it had come at a slightly different angle or slightly slower or faster would have completely burnt up in the atmosphere.” 

Thanks to the survival of these meteorite fragments, the new study—which was co-authored by over 100 experts—probed new details about the rocky relics that produce chondritic rocks. In this way, the Winchcombe meteorite bolsters the theory that Earth became habitable to life in part because space rocks brought water and organic compounds to our planet when they crashed into it more than four billion years ago. Moreover, further examination of the meteorite is likely to open a new window into our early solar system, and the emergence of life on Earth.

“There is so much more exciting science to come out of this stone, it’s impossible to cover it all,” Daly said, noting that he is personally fascinated by its diverse composition and its orbital similarities to other chondritic meteorites, which may hint that CMs largely come from the same place. 

“Because of all the amazing stories about how it was found, it was always a unique and special stone in our hearts and always will be,” he concluded. 

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