Credit: CC0 Public Domain
The unusual behavior of sulfur in the atmosphere of Venus cannot be explained by an “aerial” form of extraterrestrial life, according to a new study.
Researchers at Cambridge University used a combination of biochemistry and atmospheric chemistry to test the “cloud life” hypothesis that astronomers have been speculating on for decades, and found that life cannot explain the composition of the cloud. Venusian atmosphere.
Any life form in sufficient abundance is expected to leave chemical fingerprints in a planet’s atmosphere as it consumes food and expels waste. However, Cambridge researchers found no evidence of these fingerprints on Venus.
Even if Venus is lifeless, researchers say its results, reported in the journal Communications of natureit could be useful to study the atmospheres of similar galaxies throughout the galaxy and the eventual detection of life outside our solar system.
“We’ve spent the last two years trying to explain the strange chemistry of sulfur we see in the clouds of Venus,” said co-author Dr. Paul Rimmer of the Cambridge Department of Earth Sciences. “Life is pretty good with weird chemistry, so we’ve been studying if there’s 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 are expected to occur, given the known sources of chemical energy in Venus’ atmosphere.
“We looked at the sulfur-based ‘food’ available in the Venusian atmosphere; it’s nothing you or I would want to eat, but it’s the main source of energy available,” said Sean Jordan of the Institute. Cambridge Astronomy, the first paper in the paper. author. “If this food is being consumed by life, we should see evidence of it through specific chemicals that are lost and gained in the atmosphere.”
The models analyzed a particular feature of the Venusian atmosphere: the abundance of sulfur dioxide (SO2). On Earth, most SO2 in the atmosphere comes from volcanic emissions. On Venus, there are high levels of SO2 lower in the clouds, but it is somehow “sucked” from the atmosphere at higher altitudes.
“If there is life, it must be affecting atmospheric chemistry,” said co-author Dr. Oliver Shorttle of the Department of Earth Sciences and the Cambridge Institute for Astronomy. “Could life be the reason why SO2 levels on Venus are dropping so much?”
The models, developed by Jordan, include a list of metabolic reactions that would be carried out by lifestyles to get their “food” and waste by-products. The researchers ran the model to see if the reduction in SO2 levels could be explained by these metabolic reactions.
They found that metabolic reactions can cause a drop in SO2 levels, but only by producing other molecules in very large amounts that are not seen. The results set a hard limit on the amount of life that could exist on Venus without breaking our understanding of how chemical reactions work in planetary atmospheres.
“If life were responsible for the levels of SO2 we see on Venus, it would also break everything we know about Venus’ atmospheric chemistry,” Jordan said. “We wanted life to be a potential explanation, but when we run the models, it’s not a viable solution. But if life isn’t responsible for what we see on Venus, it’s still a problem to solve; there’s a lot of weird chemistry in it. follow”.
Although there is no evidence of life it eats sulfur hidden in the clouds of Venus, researchers say its method of analyzing atmospheric signatures will be valuable when JWST, the successor to the Hubble Telescope, begins to return images from other systems. planetariums later this year. Some of the sulfur molecules in the current study are easy to see with JWST, so learning more about the chemical behavior of our next-door neighbor could help scientists figure out similar planets across the galaxy.
“To understand why some planets are alive, we need to understand why other planets are dead,” Shorttle said. “If life somehow managed to sneak into Venusian clouds, it would completely change the way we look for chemical signs of life on other planets.”
“Even if ‘our’ Venus’ is dead, it’s possible that Venus-like planets from other systems could harbor life,” said Rimmer, who is also affiliated with Cambridge’s Cavendish Laboratory. “We can take what we’ve learned here and apply it to exoplanetary systems; that’s just the beginning.”
Could acid-neutral life forms make habitable pockets in the clouds of Venus? More information: Sean Jordan, The proposed energy metabolisms cannot explain the atmospheric chemistry of Venus, Communications of nature (2022). DOI: 10.1038 / s41467-022-30804-8. www.nature.com/articles/s41467-022-30804-8 Provided by the University of Cambridge
Citation: There are no (still) signs of life on Venus (2022, June 14) recovered on June 14, 2022
This document is subject to copyright. Apart from any fair treatment for private study or research purposes, no part may be reproduced without the written permission. Content is provided for informational purposes only.