Winchcombe meteorite is a ‘jigsaw of seven jigsaws’, finds latest analysis

The past of the iconic Winchcombe meteorite that landed in the UK in Feb 2021, has now been revealed. After detailed scrutiny of the space rock, scientists found it came from an asteroid that had been heavily altered by water as well as smashed apart and reformed multiple times.

The fragments of the 2021 meteorite were found scattered in fields near the village of Winchcombe. This was the first meteorite fall in the UK whose fragments were retrieved, since 1991. With the help of eyewitnesses’ reports and the UK Fireball Alliance’s network of cameras, scientists were able to locate the approximate area in which the meteorite had fallen.

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The fragments were retrieved as quickly as possible, to save them from any kind of contamination. Though some parts of the fragments did have some terrestrial contamination, including from table salt, the Winchcombe fragments were the most pristine parts recovered from a fallen meteorite.

Since 2021, the history of the Winchcombe asteroid has remained a secret. The internal parts of the meteorite were teased out with sophisticated transmission electron microscopy and techniques such as electron backscatter diffraction, time of flight secondary ion mass spectrometry and atom probe tomography.

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With the help of all these methods, scientists were able to retrieve the history of well-kept samples of the Winchcombe meteorite.

"This level of analysis of the Winchcombe meteorite is virtually unprecedented for materials that weren't directly returned to Earth from space missions, like moon rocks from the Apollo program or samples from the Ryugu asteroid collected by the Hayabusa 2 probe," said Leon Hicks of the University of Leicester in a statement.

What does the latest investigation show?

The latest analysis of the meteorite showed that fragments were made of breccia- where individual chunks of rock are cemented together. The Winchcombe meteorite is classified as a CM carbonaceous chondrite, which is a carbon-rich and stony rock.

The recent investigation, which probed the fragments at the nanometer scale, found that the Winchcombe breccia was formed from eight different types of CM chondrite, which are the most common variations of carbonaceous chondrite.

"We were fascinated to uncover just how fragmented the breccia was within the Winchcombe sample we analyzed," said Luke Daly of the University of Glasgow, who led the research.

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"If you imagine the Winchcombe meteorite as a jigsaw, what we saw in the analysis was as if each of the jigsaw pieces themselves had also been cut into smaller pieces and then jumbled in a bag filled with fragments of seven other jigsaws."

This implies the Winchcombe meteorite’s parent asteroid had been smashed apart and reformed multiple times, probably following collisions with other asteroids early in the solar system.

Also, the meteorite fragments had clear evidence of being chemically altered by liquid water before getting smashed apart. In some cases, grains altered by water were found right next to unaltered grains, so much jumbled had the breccia become.

(With inputs from agencies)