Madrid, 14 (European press)
Researchers at the University of Cambridge used a combination of biochemistry and atmospheric chemistry to test the “life in clouds” hypothesis, which astronomers have speculated about for decades, and found that life cannot explain the composition of Venus’s atmosphere.
Any life form in sufficient abundance would be expected to leave chemical footprints in the planet’s atmosphere by consuming food and expelling waste. However, the Cambridge researchers found no evidence of these effects on Venus.
Even if Venus was devoid of life, the researchers say their findings could be useful in studying the atmospheres of similar planets throughout the galaxy, and the eventual discovery of life outside our solar system.
“We’ve spent the past two years trying to explain the strange chemistry of sulfur that we see in the clouds of Venus,” co-author Dr Paul Reimer, from the Department of Earth Sciences at Cambridge, said in a statement. She’s very good at weird chemistry, so we’ve been looking at if there’s a way to make life a possible explanation for what we’re seeing.”
The researchers used a combination of atmospheric and biochemical models to study the chemical reactions expected to occur, given the known sources of chemical energy in Venus’s atmosphere.
– Sean Jordan of the Cambridge Institute of Astronomy, first author of the article – explains. If life is consuming this food, we should see evidence of this through certain chemicals being lost and gained in the atmosphere.”
The models looked at a particular feature of Venus’s atmosphere: the abundance of sulfur dioxide (SO2). On Earth, most of the sulfur dioxide in the atmosphere comes from volcanic emissions. On Venus, sulfur dioxide (SO2) levels are high at the bottom of the clouds, but somehow the atmosphere absorbs it.
“If there is life, it must be affecting the chemistry of the atmosphere,” says co-author Dr Oliver Shorttel, from the Department of Earth Sciences and the Cambridge Institute of Astronomy. “Could it be that life has reduced sulfur dioxide levels on Venus. So much?” he asks.
The models, developed by Jordan, include a list of metabolic reactions that life forms can undertake to obtain their “food” as well as waste by-products. The researchers ran the model to see if the decrease in sulfur dioxide levels could be explained by these metabolic reactions.
They found that metabolic reactions can lead to a decrease in sulfur dioxide levels, but only by producing other molecules in quantities that are too large to be seen.
The results put a strict limit on how much life could exist on Venus without compromising our understanding of how chemical reactions work in planetary atmospheres.
“If life was responsible for the levels of sulfur dioxide we see on Venus, it would also shatter everything we know about Venus’s atmospheric chemistry,” Jordan says. “We wanted life to be a possible explanation, but when we ran the models, it’s not a viable solution. But if life is not responsible for what we see on Venus, there is still a problem to be solved: there is a lot of strange chemistry to follow.”
Although there is no evidence that sulfur-eating life lurks in the clouds of Venus, the researchers say their method of analyzing atmospheric signals will be of value when the JWST, the successor to the Hubble telescope, begins returning images of other planetary systems later in this year. general.
It’s easy to see some of the sulfur particles in the current study with JWST, so learning more about the chemical behavior of our next door neighbor could help scientists understand similar planets across the galaxy.
“To understand why some planets survive, we need to understand why other planets die,” Shorttel said. “If life somehow managed to infiltrate the clouds of Venus, it would completely change the way we look for chemical signs of life.”
“Even if our own Venus dies, it’s possible that Venus-like planets in other systems could support life. We can take what we’ve learned here and apply it to exoplanet systems: that’s just the beginning,” says Rimmer, who also belongs to the Cavendish Laboratory in Cambridge.
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