Earth treats the shattered meteorite with a pinch of table salt

New research on a meteorite recently discovered in Britain reveals that pristine meteorites don’t really exist; Once in the Earth’s atmosphere, it undergoes various changes with remarkable speed.

You can read about it in the magazine Science of meteorites and planets. The research article stars a meteorite that landed in Great Britain a year ago. Part of it was found in a lane in Winchcombe just hours after the space rock entered Earth’s atmosphere. More fragments of the same space rock were found several days later in a nearby sheep pasture.

For the study, the scientists looked at both a stone found in the driveway and stones discovered later in a sheep pasture. And it leads to an amazing result. For example, all the rest – despite the fact that they were discovered fairly quickly – have already been altered by interaction with the Earth’s atmosphere. For example, researchers found halite — better known as table salt — on a space rock found in the pass. It was found that the shards found in the sheep pasture were fertilized with calcium sulfate and calcite.

the changes
Researcher Laura Jenkins says that these specific salts were not originally part of the meteorite, but were formed after it entered the atmosphere. Saintias. The halite was created by the reaction of a sodium-rich portion of the meteorite with moist air in a laboratory. And the sulfates were likely created by the meteorite interacting with water (eg, dew) in sheep pastures. “In either case, the feedback is related to the Earth’s atmosphere,” Jenkins said.

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mundane stages
It is remarkable that the meteorite has changed under the influence of the Earth’s atmosphere. “We recovered this meteorite quickly, so we didn’t expect to see these changes,” Jenkins said. But these changes happened quickly. Within a few months, Jenkins said. Because when the researchers examined the meteorite remains in the laboratory and found the changes, the space rock had only been on Earth for a few months. “We’ve always known that exposure to Earth’s atmosphere alters the surface of meteorites,” said lead researcher Luke Daly. “But this is the first time we can see how quickly the process is starting and progressing.”

The virgin meteorite does not exist
“The Winchcombe meteorite is often seen as a ‘original’ example of a CM chondrite (…) but what we show in this study is that pristine meteorites do not really exist,” Jenkins said. The moment a meteorite enters the Earth’s atmosphere, it already begins to undergo changes.

Take changes into account
It is important for researchers to be aware of this. Because it means that not all elements in and in such a meteorite are automatically “extraterrestrial”; Some may originate here on Earth. This (research, ed.) shows how strongly meteorites interact with our atmosphere. When analyzing meteorites, we must proceed with caution and take into account these types of changes that are caused by the Earth’s atmosphere.”

At the same time, Jenkins must also realize that it is not always easy to distinguish between items that really belong to a meteorite and items that it acquired after its journey through the Earth’s atmosphere. “Some changes – such as those that occur on the outer surface of the meteorite – are easy to detect.” But it is sometimes debatable. Think, for example, of the presence of sulfates in some of the rich clay meteorites; Then you can have discussions about whether they originated on the asteroid or are the result of erosion here on Earth.” What makes things more difficult is that we may not have discovered all the ways in which Earth leaves its mark on meteorites yet. There are other unknown ways in which the meteorite is altered by the Earth’s atmosphere or the environment in which it lands.”

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Preventing change is impossible
Preventing a meteor from changing through Earth’s atmosphere is challenging. “Earth’s atmosphere – compared to the vacuum of space – is rich in moisture and oxygen,” says Jenkins. “So limiting the time a meteorite spends in Earth’s atmosphere is the best way to prevent change from terrestrial impacts.” This can be done, for example, by spotting meteorites as soon as possible after they land on Earth. After that, it is also important to store the retrieved Space Stones carefully, preferably in areas where oxygen and water cannot (more) affect them. But even if all this succeeds, some change under the influence of the Earth’s atmosphere is inevitable. “A meteorite always spends some time in Earth’s atmosphere anyway, so it’s impossible to keep it pure,” Jenkins said.

Sample return missions
If you still wanted to study an untouched meteorite, you would have to take a completely different path and carry out missions to asteroids still living in space to sample them there and then carefully bring those samples back to Earth. “You can get the best samples through sample returnsmissions,” Jenkins confirms.

Incidentally, this does not mean that meteorites impacting the Earth’s atmosphere are of no value at all; Even untouched space rocks can tell us a lot. “The Winchcombe meteorite (…) has already yielded wonderful insights,” says Jenkins. Researchers have previously established this The meteorite harbors water very similar in composition to water on Earth. He hints that this type of space rock – carbonaceous chondrites – may have brought water to Earth in the past and thus played an important role in the origin of the oceans and thus life on our planet.

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