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Astronomie - Have we really found an alien protein inside a meteorite?

5.03.2020

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A team of researchers claim to have found a protein inside a meteorite. It would be the first protein ever discovered from beyond Earth, though not an indication of alien life – and other scientists are sceptical the analysis really found anything at all.

We know that amino acids, which are organic compounds that act as the building blocks of life, can form on meteors and other space rocks. But the extent of prebiotic chemistry beyond Earth is still unknown, and how that chemistry turns into life is even more mysterious.

That is partly because the process of looking for organic compounds in meteorites on Earth is extremely difficult. “You can’t just go into the meteorite, pull out a piece of it, analyse it and go: ‘OK, I found this this and that’,” says Dimitar Sasselov at Harvard University, who wasn’t involved in the research. “The devil is in the details.”

 

 

Julie McGeoch, also at Harvard University, and her colleagues analysed a pristine sample of a meteorite that was found in Algeria in 1990. First, they used a series of small, carefully sanitised drills – similar to dentistry ones – to collect material from deep inside the meteorite.

The researchers prepared the resulting powder by mixing it with liquids including water and chloroform. Finally, they fired a laser at the samples to turn them into gases, which are easier to analyse in a process called mass spectrometry.

When they examined the gases, the researchers found a combination of amino acids and additional atoms, which they say is evidence for the first extraterrestrial protein. When contacted by New Scientist, they declined to comment on their work.

“If this passes a technical review, then I would consider it to be an important result,” says Sasselov. “It points to certain types of chemical reactions which could have occurred on the surface of the Earth or other planets which could have led to or helped the emergence of life.”

If this chemistry could occur on a barren rock in the vacuum of space, that could mean it is easier to make the building blocks of life in more extreme environments than we thought, he says. “It’s additional confirmation that this chemistry is something that can happen in nature, not just that humans can do in a lab.”

However, several other researchers contacted by New Scientist expressed scepticism about the results. “If we could find a protein in a meteorite that wasn’t from Earth, then that would be amazing,” says Lee Cronin at the University of Glasgow in the UK – but he doesn’t think that is the case here.

The results of the analysis don’t necessarily mean that the compound the researchers claim is in the meteorite really is there, he says. Instead, he says they are extrapolating from incomplete data. The protein they claim to have found is also unlikely to occur in nature, he says. “The structure makes no sense.”

Still, Sasselov says that we are likely to continue discovering complex organic molecules, amino acids and possibly even proteins on space rocks. “It just needs to be worked on more, and I hope this really leads somewhere,” he says.

Quelle: NewScientist

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