'Fireball' that fell to Earth is full of pristine extraterrestrial organic compounds, scientists say

Andrew Griffin
Tuesday 27 October 2020 14:07 GMT
Security camera footage shows 'fireball' meteor over Toledo in Ohio
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A fireball that fell to Earth in 2018 contains “pristine extraterrestrial organic compounds” that could help tell us how life formed, scientists say.

The meteor arrived on Earth in January 2018, as a streaking fireball visible across the sky of the US Midwest. Scientists were able to track it using weather radar, and hunters picked the meteorite up from the ground before its chemical makeup was changed by exposure to liquid water.

Now researchers say the material they recovered offers them the ability to explore such rocks as they might appear when they are still in space, but using the equipment they have down on Earth.

They describe their early findings in a new paper published in the journal Meteoritics & Planetary Science.

"This meteorite is special because it fell onto a frozen lake and was recovered quickly. It was very pristine. We could see the minerals weren't much altered and later found that it contained a rich inventory of extraterrestrial organic compounds," says Philipp Heck, a curator at the Field Museum, associate professor at the University of Chicago, and lead author of the new paper.

"These kinds of organic compounds were likely delivered to the early Earth by meteorites and might have contributed to the ingredients of life."

As the fireball arrived, researchers were able to track the pieces using Nasa technology usually reserved for monitoring the weather.

"Weather radar is meant to detect hail and rain," said Heck. "These pieces of meteorite fell into that size range, and so weather radar helped show the position and velocity of the meteorite. That meant that we were able to find it very quickly."

The first pieces were retrieved by meteorite hunter Robert Ward, who found it on the frozen surface of Strawberry Lake in Michigan. He gave his discovery to the Field Museum, which began the research that culminated in the newly published paper.

That research showed that the meteorite was an H4 chondrite, which represents only 4 per cent of the objects that fall to Earth. But it was even more remarkable because it was picked up so quickly that it remains relatively untouched by the conditions on Earth.

That could help researchers in their quest to understand how the organic compounds that helped life form arrived on Earth. One of the possibilities is that they were brought to the planet by similar meteorites, and so studying such examples could help us understand whether such a story is likely.

"Scientists who study meteorites and space sometimes get asked, do you ever see signs of life? And I always answer, yes, every meteorite is full of life, but terrestrial, Earth life," says Heck.

"As soon as the thing lands, it gets covered with microbes and life from Earth. We have meteorites with lichens growing on them. So the fact that this meteorite was collected so quickly after it fell, and that it landed on ice rather than in the dirt, helped keep it cleaner."

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