As the British settled down to watch the late night news on February 28, news, literally, appeared in the night sky. A large and very bright fireball was seen over southern England and northern France at 21:54 GMT. It was recorded by many doorbell webcams, so it was a very well watched fireball. More importantly, it was also captured by automated cameras from the UK Meteor Observation Network and similar networks.
Working with colleagues in France and Australia, meteor watchers worked out the fireball’s path and determined where the meteorite pieces could be located, just north of Cheltenham in the UK. Based on their calculations, Ashley King, a meteorite specialist at the Natural History Museum in London, appealed to local TV and radio stations for information about the unusual black rocks that fell from the sky.
Among the photographs he received, there is one that caught his attention: a small mound of dust and pebbles on an alley in the small village of Winchcombe. King asked Open University researcher Richard Greenwood (who lived closest) to verify the sample. Greenwood was shocked to find that not only was it a meteorite, but it was also a very rare species. The UK had been lucky – we had a new member to add to our meteor collection.
Over the next four days, specialist researchers from several British institutions formed teams to systematically search the countryside surrounding Winchcombe. The results of their work are several stones weighing about 500 g, plus a lot of dust and fragments. The specimens are now in the Natural History Museum.
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Why is this such a big deal? Meteorites are divided into two main groups: primitive and processed. The primitives come from the solar nebula which gave birth to the solar system, preserving the composition of this original material. In contrast, the processed samples were modified by heat. They come from larger bodies and contain information about planetary surfaces and interiors.
The stones that fell on Winchcombe belong to the old group – and not only, they belong to a subcategory, known as carbonaceous chondrites – the most pristine (or unchanged) of all meteorites, bearing records of the early stages of the solar system. the story. They are rich in organic compounds: the molecules that form the building blocks of life. They also contain tiny particles of stardust that are dead and older than the Sun.
Some of the rocks found are almost completely black and without streaks, while others are dark gray with irregular, pale patches. Obviously, this is a complex meteorite, possibly coming from the surface of an asteroid where several different pieces of asteroid have mixed together in collisions.
And this is where things get a little ironic: Scientists are currently collecting samples from two asteroids in space. About five grams of material collected by the Japanese mission Hayabusa2 on the asteroid Ryugu arrived unharmed in December 2020. NASA’s Osiris-Rex mission is returning from the asteroid Bennu with about 200 g of material that will arrive in September 2023. These missions are expensive. money, but could help unravel the secrets of the origins of life and the solar system. And then, just out of nowhere, nearly 500g of rock from an asteroid, which is perhaps very similar to Ryugu and Bennu, falls over part of England.
British meteorites will now analyze the material, practically grain by grain. Things need to happen in a sequence – there are time sensitive measurements that need to be taken in the first month or so of a new fall. Meteorites are not radioactive – they do not emit harmful radiation – but they contain unstable and disintegrating elements. And if we can measure the amounts of elements that decay very quickly, we can get valuable information.
We also need to carefully examine the meteorite’s organic compounds – there is always a risk of contamination from the Earth. So the faster we can analyze its organics, the better. The more we can understand these materials in meteorites, the more we can piece together the chemistry that led to life on Earth. This can give an idea of the extent of this chemistry (or has been) in the solar system – and even in the universe.
Searching for a meteorite in a small village and its surrounding fields is generally not dangerous and requires little risk assessment: ask the owners for permission to access their land, observe the country code, forget not to close the doors, and do not. walk in all that is sweet. But in times of pandemic, everything changes.
The UK government currently prohibits citizens from traveling far from home, unless travel is essential. Was it essential for a group of meteorites to get to Winchcombe? Yes it was. Each had carried out risk assessments in the field and had received travel authorization from their institutions. They were scrupulous in wearing masks and keeping a distance of 2m when talking to locals.
I would have liked to have been involved in the research – although my colleague Sara Russell told me that cleaning the owner’s driveway with a covered toothbrush after the first hour. My arthritic knees wouldn’t have coped with this. But I was back at base, doing something equally important: turning on machines to sort out the risk assessment documents for Greenwood. And, as a reward, I got to see the first close-up photos of our newest family member, nicknamed “Winchcombe”. It may look a bit like a broken barbecue briquette, but to me it’s absolutely gorgeous.
This article by Monica Grady, professor of planetary and space sciences, The Open University is republished from The Conversation under a Creative Commons license. Read the original article.