(ORDO NEWS) — The unusual behavior of sulfur in Venus’s atmosphere cannot be explained by an “airy” form of extraterrestrial life, a new study says.
Scientists at the University of Cambridge used a combination of biochemistry and atmospheric chemistry to test the “cloud life” hypothesis that astronomers have been speculating about for decades, and found that life cannot explain the composition of Venus’s atmosphere.
Any life form in sufficient numbers should leave chemical fingerprints in the planet’s atmosphere as it consumes food and discards waste. However, the Cambridge researchers did not find any signs of such imprints on Venus.
The researchers used a combination of atmospheric and biochemical models to study the chemical reactions expected to take place given the known sources of chemical energy in Venus’s atmosphere.
The models considered one feature of the Venusian atmosphere – the abundance of sulfur dioxide (SO2). On Earth, most of the SO2 in the atmosphere comes from volcanic emissions. On Venus, high levels of SO2 are found lower in the clouds, but it is somehow “sucked” out of the atmosphere at high altitudes.
The researchers ran a model of metabolic reactions to see if they could explain the decline in SO2 levels. They found that metabolic reactions can lower SO2 levels, but only by producing other molecules in very large quantities that are not visible.
The results set a hard limit on how much life can exist on Venus without destroying our understanding of how chemical reactions work in planetary atmospheres – it turns out that this is not a viable solution.
There’s no evidence that sulfur-eating life lurks in the clouds of Venus, but researchers say studying our neighbor’s chemical behavior could help scientists figure out how similar planets across the galaxy behave.
“Even if ‘our’ Venus is dead, it is possible that life could exist on Venus-like planets in other systems,” the scientists conclude.
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