Flame Encounter! The correct way to find fireball meteorites on the road, will this be possible?

How scientists found a rare fireball meteorite on a road, and what it can teach us

Fireball photographed on February 28

(The picture belongs to the British Meteor Network and is provided by the original author)

As residents of the United Kingdom began to watch the evening news on February 28, 2021, a truly big news flashed across the night sky above them. At 21:54 GMT, a huge bright fireball could be seen across England. And because the fireball was captured by many street webcams, it became a carefully observed celestial body. More importantly, the fireball was captured by the British Meteor Observation Network and some automatic cameras of similar networks. Local professional meteorite observers, together with colleagues in Australia, calculated the trajectory of the fireball and gave the location where the fireball fragments fell: north of the city of Cheltenham, England. Based on these calculations, Ashley King, a meteorite expert at the National History Museum in London, began to issue an appeal on local TV and radio stations to collect information about the unusual black meteorite fragments.

Among the photos he collected, one captured dust and pebbles on the side of the road in a small village in Winchcombe caught King's attention. King asked Richard Greenwood, a researcher at the Open University, to examine the sample. After the inspection, Greenwood was very excited about their discovery: this fireball was not an ordinary meteorite, it belonged to a very rare type of meteorite. In fact, British scientists caught a once-in-a-lifetime opportunity: they contributed a brand new sample to mankind's meteorite collection.

The main materials of meteorite fragments on the road (the picture belongs to the owner of this road and is provided by the original author)

Over the next four days, a team of experts from several British institutions systematically searched the village around Winchcombe. They found some stones weighing about 500 grams and a lot of dust and debris. These samples are now stored in the National History Museum.

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But why is this fireball so significant?

Meteorites fall into two main categories: primitive and processed. Primitive meteorites come from the nebula that gave rise to the solar system, and they retain components of the original raw materials. Processed meteorites, on the other hand, are the opposite, having been shaped at high temperatures. These meteorites come from larger bodies and carry information about the surface and interior structure of planets.

A 4-gram meteorite fragment (Photo courtesy of the Natural History Museum, courtesy of the original author)

The rocks that fell at Winchcombe are primitive meteorites. Not only that, they belong to a subclass of primitive meteorites: carbonaceous chondrites. These meteorites have undergone the least natural alteration. Therefore, they record the history of the earliest days of the solar system. In addition, they are rich in organic compounds (the main molecules that make up life), as well as some dust from dead stars, or stars older than our sun.

Some of the newly discovered meteorite pieces are almost completely black and featureless; other fragments have a dark gray color and irregular white patches. Clearly, this fireball is a complex meteorite. Perhaps it is a fragment of an asteroid surface that flew out of a collision of multiple asteroids.

However, this discovery in the UK is somewhat ironic: before this, scientists were collecting asteroid samples from outer space. The asteroid probe Hayabusa 2 has collected 5 grams of material from Ryugu, which has safely arrived on Earth as early as December 2020; and NASA's "Source Spectral Interpretation Resource Security Regolith Identification Explorer" is transporting about 200 grams of material from asteroid 101955 back to Earth, and is expected to arrive in September 2023. These costly missions can help us uncover the secrets of the origin of life and the sun. However, out of thin air, a meteorite belonging to an asteroid very similar to Ryugu and 101955 visited the UK.

Next Stage

The UK's meteorite experts will begin analysing the material almost grain by grain. The analysis must be done in a certain order - some time-sensitive measurements must be made in the first month of the new autumn. Of course, meteorites themselves are not radioactive - they do not emit harmful radiation - but they do contain some unstable elements that break down very easily. Therefore, if we can measure the content of these fast-decaying elements, we can get very valuable information.

At the same time, we must also look carefully at organic compounds in meteorites—there is always the risk of contamination from the Earth's environment. So the sooner these organic compounds are analyzed, the better. The more we understand these substances in meteorites, the more accurate and richer our inferences about the chemical history that formed life on Earth will be. This will give us a better sense of how chemicals are currently (or have been) distributed throughout the solar system—and even the universe.

Normally, searching for meteorite fragments in a small village and the fields around it is not a big adventure, and there is no need to assess the risks. You just need to apply for permission from the field owner, follow local guidelines, remember to close the gate after entering the field, and don't step on anything soft. But the arrival of the epidemic has changed everything.

Now, the British government prohibits citizens from traveling far away unless it is essential to go out. So, is it necessary to bring a group of meteorite experts to Winchcombe? The answer is yes. Each researcher has completed a risk assessment for field exploration and received approval to leave their unit. They strictly abide by the rules of wearing masks and keeping at least 2 meters away from local residents.

A larger meteorite, about 5 centimeters long. Its surface is the remnant of the surface that was detached from the meteorite when it passed through the atmosphere. (Photo courtesy of Richard Greenwood, provided by the author)

I was eager to be part of the research—even though my colleague Sarah Russell told me that the team used toothbrushes to clean the landowners' roads. And the work stopped after the first hour. I have arthritis in my knees, so I'm not suitable for field research, but I'm providing support for the team to get the organization running to help Greenwood sort through those risk assessment documents, which is just as important as the field trip. In return, I got to see the first close-up photos of the new meteorite, "Winchcomb." Maybe it looks a bit like a broken barbecue coal, but to me, it's beautiful.

BY: Monica Grady

FY: Chen Yuchong

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