Finding and analysing the Winchcombe meteorite

A variety of images from the JEOL 7001F SEM within PEMC. The top images (black and white) are backscattered electron images, showing atomic contrast in the Winchcombe meteorite; bright areas are metal-rich, containing nickel, iron, or chromium, whereas darker areas are mineral-rich. The bottom, coloured images are combined X-ray element maps of the same regions, showing chemical composition of the mineral and metal grains. These maps show the variety of different textures, size and composition of grains within the Winchcombe meteorite

The challenge of collecting meteorites

There are more than 70,000 known meteorites on Earth and over 1,000 the size of a football are believed to fall to Earth every year. However, only 1,206 have been witnessed to fall and, of these, only 51 are carbonaceous chondrites. The last meteorite that was discovered in the UK was the Glatton meteorite that landed in a residential garden in 1991.
Dr Natasha Stephen, Director of the Plymouth Electron Microscopy Centre (PEMC), has spent more than a decade analysing meteorites and has been on meteorite hunting expeditions all over the world. She said: 
“I’ve been hunting for meteorites several times but never in the UK before Winchcombe. At the time of the last UK event, I was only just starting school, so to have the opportunity to find a UK meteorite as a professional meteorite scientist is just amazing, and not something I was sure would ever happen here at home.”

<p>Dr Natasha Stephen searching for meteorite fragments</p>

Dr Natasha Stephen during the search for fragments of the Winchcombe meteorite

Finding fragments of the Winchcombe meteorite

The Winchcombe meteorite lit up the sky over the UK and Northern Europe. The fireball was seen by thousands of eyewitnesses across the UK and northern Europe, many of whom reported it to the UK Meteor Observation Network, and was captured on many fireball cameras and home surveillance cameras when it fell to Earth at 21:54 on Sunday 28 February, 2021. Hundreds of pieces of the rare meteorite survived its passage through the Earth’s atmosphere and landed in and around the town of Winchcombe, Gloucestershire. Specialised cameras located across the country as part of UK Fireball Alliance (UKFAll) were able to recreate the flight path, allowing scientists to determine exactly where in the solar system it came from, and predict where it fell.
Having hastily secured permissions and conducted risk assessments, with the UK still covered by a national lockdown, Dr Stephen was the third scientist on the scene and was part of a collaborative effort to locate and analyse fragments. 
The recovery mission was led by researchers at the Natural History Museum and also involved experts from The University of Glasgow, The University of Manchester, The Open University, and Imperial College London. The meteorite was retrieved in such a good condition so quickly after its fall, it is comparable to samples returned from space missions, both in quality and quantity.
<p>A fragment of the Winchcombe meteorite (Credit: Trustees of the Natural History Museum)<br></p>
Images courtesy of Trustees of the Natural History Museum
<p>Meteorites recovered from Winchcombe CREDIT Trustees of the Natural History Museum<br></p>
<p>Scientists examine part of the meteorite recovered from Winchcombe 

(Credit: Trustees of the Natural History Museum)

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<p>Meteorite recovered from Winchcombe CREDIT Trustees of the Natural History Museum<br></p>

A coordinated effort to analyse samples

Initial analyses of the meteorite were funded by the Science and Technology Facilities Council (STFC), and each member of the UK Cosomochemistry Analysis Network was provided with a small fragment to start working on straight away. It enabled the project team to use X-rays and learn about how the meteorite was formed, while the Natural History Museum invested in state-of-the-art curation facilities and supported time-sensitive mineralogical and organic analyses in specialist laboratories at several leading UK institutions.
In Plymouth, this was carried out by the Space Rocks UK group using the cutting-edge facilities of Plymouth Electron Microscopy Centre (PEMC). Investigating the sample in a non-destructive way, researchers were able to quickly establish that their sample contained multiple types of rock, and one was more metal-rich than the other. The scientists could see the extensive alteration in the sample, the result of fluids interacting with minerals within, and the hydrated phases and fine-grained nature made the investigation interesting from a technical point of view. It meant they were suddenly working with incredibly small features, even for electron microscopy.
<p>A resin-mounted sample of the Winchcombe meteorite. This whole block is placed inside the scanning electron microscope and imaged non-destructively using electron beams and X-rays<br></p>
<p>Live data on our JEOL 7001F scanning electron microscope. Each colour represents a different chemical element, analysed using X-rays, showing a combined chemistry image on the left monitor and individual element X-ray maps on the right monitor<br></p>
<p>The Plymouth team analysing samples -&nbsp;Dr
Natasha Stephen (front), postgraduate student Cesca Willcocks (middle) and technical specialist Dr Jennifer Mitchell (back)



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A tantalising glimpse into Earth’s origins

In a study published in Science Advances in November 2022, researchers identified the meteorite to be a rare CM carbonaceous chondrite containing approximately 2% carbon (by weight) and is the first ever meteorite of this type to be found in the UK. Detailed imaging and chemical analyses determined it contains approximately 11% extra-terrestrial water (by weight), most of which is locked-up in minerals that formed during chemical reactions between fluids and rocks on its parent asteroid in the earliest stages of the solar system. It has also been found to contain extra-terrestrial water and organic compounds that reveal insights into the origin of Earth’s oceans. Extracts from the Winchcombe meteorite also contain extra-terrestrial amino acids – prebiotic molecules that are fundamental components for the origin of life.
Dr Stephen said: 
“It’s really exciting to finally see this information in the public domain. This is the first in a series of studies that the Winchcombe science team has prepared, but it reveals some of the headline findings that are so important – and often unique – to this meteorite. The quick recovery and almost immediate scientific analyses gave us an unrivalled window into asteroidal processes preserved in this carbonaceous rock. Coupled with the calculated pre-atmospheric orbits, it makes the Winchcombe meteorite very special indeed.”