No signs of life found on Aphrodite (yet)

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Sulfur’s unusual behavior in Venus’s atmosphere cannot be explained by an “airy” form of extraterrestrial life, says a new study.

That’s what Cambridge University says, reports.

The researchers used a combination of biochemistry and atmospheric chemistry to test the “life in the clouds” hypothesis that astronomers have speculated about for decades and found that life could not explain the composition of Venus’s atmosphere.

Any form of life in sufficient numbers should leave chemical imprints on the planet’s atmosphere as it eats and discards waste. However, researchers from Cambridge did not find evidence of such imprints on Aphrodite.

Even if Venus is lifeless, the researchers say their results could be useful in studying the atmospheres of similar planets across the galaxy and possibly detecting life outside our solar system.

“We’ve spent the last two years trying to explain the strange sulfur chemistry we see in Venus clouds,” said study co-author Dr. Paul Rimmer of the Cambridge Department of Earth Sciences. “In weird chemistry, life is pretty good, so we looked at whether there was a way to make life a possible explanation for what we see.”

The researchers used a combination of atmospheric and biochemical models to study the chemical reactions that would occur given known sources of chemical energy in Venus’s atmosphere.

“We looked at the sulfur-based ‘food’ available in Venus’s atmosphere – it’s not something you or I would like to eat, but it is the main source of energy available,” said Sean Jordan of the Cambridge Astronomy Institute. first author. of paper. “If this food is consumed by life, we need to see evidence of it through specific chemicals that are lost and gained in the atmosphere.”

The models considered a feature of Venus’s atmosphere – a large amount of sulfur dioxide (SO2). On Earth, most of the SO2 in the atmosphere comes from volcanic emissions. In Venus, high levels of SO2 appear below the clouds, but are somehow “sucked” out of the atmosphere at high altitudes.

“If there is life, it should affect atmospheric chemistry,” said study co-author Dr Oliver Shortl of the Cambridge Department of Geosciences and the Institute of Astronomy. “Could life be the reason SO2 levels in Venus fall so much?”

The models developed by Jordan include a list of metabolic reactions that life forms will take to obtain their “food” and by-products. The researchers ran the model to see if these metabolic responses could explain the reduction in SO2 levels.

They found that metabolic reactions can lead to a decrease in SO2 levels, but only by producing other molecules in very large quantities that are not observed. The results set a harsh limit on how much life there can be on Venus without destroying our understanding of how chemical reactions work in planetary atmospheres.

“If life were responsible for the SO2 level we see in Venus, it would also break all our knowledge of Venus’ atmospheric chemistry,” Jordan said. “We wanted life to be a possible explanation, but when we managed the models, it turned out that this was not a viable solution. “But if life is not responsible for what we see in Venus, that’s still a problem that needs to be solved – there are a lot of weird chemical processes going on.”

Although there is no evidence that life is eating gray in the clouds of Venus, the researchers say that the method of analyzing atmospheric signatures will be useful when the successor to Hubble JWST begins to depict other planetary systems later this year. Some of the sulfur molecules in this study are easily visible with JWST, so studying our neighbor’s chemical behavior will help scientists find similar planets across the galaxy.

“To understand why some planets are alive, we need to understand why other planets are dead,” says Shorttle. “If life somehow managed to reach the clouds of Venus, it would completely change the way we look for chemical signs of life on other planets.”

“Even if our Venus is dead, there is likely to be life on Venus-like planets in other systems,” Reimer said. “We can take what we have learned here and apply it to extraterrestrial systems – that is just the beginning.”

The results of their study were published in the journal Nature Communications.

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