Sulfur-metabolizing air life can not explain the composition of Venus' atmosphere, say researchers |  Sci-News.com

Sulfur-metabolizing air life can not explain the composition of Venus’ atmosphere, say researchers | Sci-News.com

In new research, a team of researchers at the University of Cambridge has testedlife in the Venusian clouds‘ hypothesis.

Jordan et al.  show that the three sulfur-based metabolic pathways proposed for Venous air life are capable of reproducing the observed sulfur dioxide depletion in the Venus cloud layer, but in any case they require a source of chemical reducing power that is about the same as sub-cloud sulfur dioxide: otherwise the atmosphere has not sufficient reducing force for life to utilize to generate the observed sulfur dioxide depletion.  Image credit: Mattias Malmer / NASA.

Jordan et al. show that the three sulfur-based metabolic pathways proposed for Venous air life are capable of reproducing the observed sulfur dioxide depletion in the Venus cloud layer, but in any case they require a source of chemical reducing power that is about the same as sub-cloud sulfur dioxide: otherwise the atmosphere has not sufficient reducing force for life to utilize to generate the observed sulfur dioxide depletion. Image credit: Mattias Malmer / NASA.

Life in the clouds of Venus, if there is enough, must affect atmospheric chemistry.

It has been suggested that abundantly Venusian life could get energy from their environment with the help of three possible sulfur energy metabolisms.

These metabolisms increase the risk of Venus’ mysterious cloud layer depletion of sulfur dioxide (SO)2) be caused of life.

“We have spent the last two years trying to explain the strange sulfur chemistry we see in the clouds of Venus,” says Dr. Paul Rimmer, Researcher at the Department of Earth Sciences and the Cavendish Laboratory at the University of Cambridge and the MRC Laboratory of Molecular Biology.

“Life is pretty good at weird chemistry, so we’ve studied if there is a way to make life a potential explanation for what we see.”

In the study, Dr. Rimmer and his colleagues 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 not something you or I would like to eat, but it is the main source of energy available,” explained Dr. Sean Jordan, a researcher at the Institute of Astronomy at the University of Cambridge.

“If that food is consumed by life, we should see evidence of it by losing specific chemicals and accumulating in the atmosphere.”

The team’s models looked at the abundance of sulfur dioxide in the Venusian atmosphere.

On Earth, most of the sulfur dioxide in the atmosphere comes from volcanic emissions. On Venus, there are high levels of sulfur dioxide further down in the clouds, but somehow it is “sucked out” of the atmosphere at higher altitudes.

“If life is present, it must affect the chemistry of the atmosphere. Can life be the reason why the levels of sulfur dioxide on Venus decrease so much?” said Dr Oliver Shorttle, a researcher at the Department of Earth Sciences and the Institute of Astronomy at the University of Cambridge.

The models include a list of metabolic reactions that life forms would perform to get their “food” and 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 the metabolic reactions can result in a reduction in sulfur dioxide levels, but only by producing other molecules in very large amounts that are not visible.

The results set a hard line for how much life could exist on Venus without blowing apart our understanding of how chemical reactions work in planetary atmospheres.

“If life were responsible for the sulfur dioxide levels we see on Venus, it would also break everything we know about Venus’ atmospheric chemistry,” said Dr. Jordan.

“We wanted life to be a potential explanation, but when we drove the models, it’s not a sustainable 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.”

A paper if the results were published in the journal Nature communication.

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S. Jordan et al. 2022. Proposed energy metabolisms can not explain the atmospheric chemistry of Venus. Nat Commun 13, 3274; doi: 10.1038 / s41467-022-30804-8

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