On 28 February, cameras captured a meteoroid entering Earth’s atmosphere in a blaze of yellow-green glory.
This event dropped an extremely rare type of meteorite that has never fallen in the UK before, and is the first recovered meteorite in the country for 30 years – a true first for UK science.
The meteorite is also the first to be recovered in the UK after its journey through our atmosphere was captured on camera – in this case, by the UK Fireball Alliance (UKFAll) and over 1000 eyewitnesses across the UK and Northern Europe. UKFAll is a collaborative data-sharing initiative involving researchers from Imperial College London and the University of Glasgow and citizen scientists, and forms part of the internationally collaborative Global Fireball Observatory.
Dr Sarah McMullan of Imperial’s Department of Earth Science and Engineering, who leads Imperial’s contribution to UKFAll, was among the team of UK scientists who helped recover the meteorite. “Last Sunday’s spectacular fireball was captured by three of our cameras, as well as many other cameras belonging to partner networks within the UK Fireball Alliance. It’s amazing that we’ve been able to contribute to the recovery of this rare and important meteorite.”
"It’s amazing that we’ve been able to contribute to the recovery of this rare and important meteorite." Dr Sarah McMullan Imperial's ESE and UKFAll
Imaging of the fireball allowed researchers, including colleagues at the Global Fireball Observatory, to quickly pinpoint where fragments were likely to land and, crucially, to back-track to where it originated from within the asteroid belt. Determining where a meteorite has come from is impossible without observations of the initial fireball, and has only been achieved for about 40 of the 65,000 meteorites on Earth.
Publicity from the fireball imaging, alongside collaboration with local citizens, enabled the speedy retrieval of the meteorite. Almost 300 grams of the meteorite survived its fiery fall to land on a driveway in the Cotswold town of Winchcombe, with other small pieces also recovered in the local area. These fragments are now held at the Natural History Museum (NHM) in London.
Dr Ashley King, UK Research and Innovation Future Leaders Fellow in the Department of Earth Sciences at the NHM, was among the first on the scene when the meteorite was discovered on Wednesday. He says: “Nearly all meteorites come to us from asteroids, the leftover building blocks of the solar system. The opportunity to be one of the first people to see and study a meteorite that was recovered almost immediately after falling is a dream come true!”
Primitive and pristine
The meteorite is a carbonaceous chondrite, a class that comprises some of the most primitive space rocks known. These rocks formed in the very earliest days of the Solar System and have remained largely unchanged in the many millions of years since, and so provide a pristine window into our cosmic past.
“Studying such rocks can provide unique information on where water and the building blocks of life were formed, and what planets are made from – some of the biggest questions asked by the scientific community,” says Dr Matt Genge of Imperial’s Department of Earth Science and Engineering. “It's also fascinating that much of it fell to bits as dust, since it shows how these weak asteroids behave, and explains why dust from these objects continually falls through our atmosphere.”
However, carbonaceous chondrites represent just a small proportion of meteorite falls, with only 51 of the approximately 1200 observed meteorite falls on Earth belonging to this category.
Although the meteorite blazed through our atmosphere at 14 kilometres per second, its interior remained cold and unchanged. Because it was recovered so quickly it also escaped damage by rain and weather, which can quickly render a meteorite far more complicated to analyse.
“It’s amazing! The meteorite was retrieved so soon after its fall and in such pristine condition that it’s almost like a sample returned from a space mission,” adds Gareth Collins, Professor of Planetary Science at Imperial’s Department of Earth Science and Engineering. “With the added value of a known orbit allowing us to pin down where this space rock came from, the UK has in a way just had its own natural asteroid sample return mission.”
Goodwill and teamwork
Each of the UK’s six meteor camera networks and three international teams contributed data to the meteorite hunt. Dr Sarah McMullan of the Department of Earth Science and Engineering, added: “By working together, UKFAll managed to quickly calculate the orbit and potential fall location of any meteorites and then make their speedy recovery. We were extremely lucky that a large meteorite fell on someone's driveway and so was able to be recovered within 12 hours of the fall in pristine condition. The event has allowed us to test out our systems, so we’re ready to act as quickly and effectively in the next event, so hopefully we won’t have to wait another 30 years for the next one!”
“Goodwill and teamwork have produced a stellar result.” Dr Luke Daly University of Glasgow and UKFAll
Imperial’s contribution to the UK Fireball Alliance is the UK Fireball Network, a network that currently includes six specialised fireball cameras deployed around the UK, supported by funding from the Science and Technology Facilities Council and the Australian Research Council. The UK Fireball Network is coordinated by Dr Sarah McMullan of Imperial and Dr Luke Daly of the University of Glasgow, and is part of Australia’s Curtin University-led Global Fireball Observatory.
Dr Luke Daly, also a member of the search and retrieval team for the ‘Winchcombe meteorite’ and an Imperial ESE Geology graduate, added: “It’s thanks to UKFAll and our international partners at Curtin University and the French FRIPON camera network that we were able to calculate where this meteorite landed so quickly, as well as where it originated from in the asteroid belt. Goodwill and teamwork have produced a stellar result.”
More to be discovered
More fragments may yet be discovered, and specialist scientists – including Dr Sarah McMullan and colleagues from The University of Glasgow, The University of Manchester, The Open University, The University of Plymouth, and Imperial – continue to search.
Professor Phil Bland, Director of the Space Science and Technology Centre at Curtin University, which leads the Global Fireball Observatory, says: “This is in true spirit of the Global Fireball Observatory collaboration – recovering rare meteorites with known orbits. It is an incredible first recovery for our UK colleagues and a fantastic demonstration of the unprecedented power of collaboration in unravelling the mysteries of our solar system.”
Parts of the fragile meteorite may be found as black stones, or as piles of tiny rock or even dust. The team advises anyone who finds something that could be meteorite to take a photograph, record its location, collect the sample using a gloved hand or aluminium foil, and then contact the Natural History Museum, all while respecting local lockdown COVID-19 regulations.
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