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Life-Building Compounds Found In Comet’s Dust Clouds

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Scientific instruments on the Rosetta spacecraft have detected amino acids and elements that are vital to life in the cloud of gases surrounding Comet 67P/Churyumov-Gerasimenko, reports

These findings are the first of their kind, and add evidence to the theory that comets and meteors could have played a big role in the early development of life on Earth.

The amino acid glycine, along with some organic molecules and the element phosphorous, were spotted by the Rosetta spacecraft, which has been circling the comet since 2014. While glycine has been previously extracted from dust samples taken from comets before, brought back y NASA’s Stardust mission, this is the first time these compounds have been seen in space, naturally vaporized.

Kathrin Altwegg of the University of Bern in Switzerland is the primary scientist for the Rosetta mission’s ROSINA instrument.

With all the organics, amino acid and phosphorus, we can say that the comet really contains everything to produce life — except energy,

she says. “Energy is completely missing on the comet, so on the comet you cannot form life. But once you have the comet in a warm place — let’s say it drops into the ocean — then these molecules get free, they get mobile, they can react, and maybe that’s how life starts.”

Glycine, which is one of the simplest amino acids, is generally bound up as a solid, making it difficult to spot from far away, Altwegg says. Scientists have long been searching for glycine in star-forming regions of space. In this discovery, the Rosetta was close enough to the comet to pick up the glycine released by the comet’s dust material as they were heated by the sun.

Amino acids form the foundation for proteins, which are complex molecules that are important to life on Earth. Altwegg’s team tried looking for other amino acids around the comet, but glycine was the only one found, as this is the only amino acid that can form without liquid water.

Altwegg theorizes that the glycine most likely didn’t form on the comet itself, but in the dust and debris present in the solar system when planets and planetary bodies formed. “The solar system was made out of material which formed in a disk, in a solar nebula,” Altwegg says. “In these clouds, it’s pretty cold, so the chemistry you do there is catalytic chemistry on the dust surfaces. And these very small dust grains [1 micron in size] are very good to lead to organic chemistry. This is also done in the lab.”

Earth was too hot for similar sensitive amino acids to survive its formation, Altwegg says. Only the smallest bodies in the solar system stayed cold, so the glycine that formed then could have helped life that was newly forming on Earth if comets had brought it.

More complex amino acids need liquid water to form, so they would have formed on Earth. The Rosetta findings corroborate this as glycine was the only amino acid found near Comet 67P.

Altwegg’s team is currently analyzing all the organics the Rosetta found. “And I think the next step goes to the biochemists, how to make something meaningful out of this,” Altwegg says.

This discovery is important to researchers who are trying to understand the early solar system. “For astrobiology, it’s a very important measurement,” Altwegg says. “And it’s not only life on Earth; the material in comets has been formed in a protostellar cloud, and what could have happened here in our protostellar cloud could have happened everywhere in the universe. Then you can ask yourself the question: How many Earths are there, how many evolved life or re-evolved life?”

The study was published in the journal Science Advances.

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