New analysis finds no sign of life on Venus after conflicting claims

(ORDO NEWS) — A new and careful analysis of the chemical composition of the clouds on Venus has not revealed any of the biomarkers that point to sulfur-metabolizing life in the air.

For now, that means the question of finding life in the clouds. Venus pretty much responded. Until we get new information, most likely it will remain so. The complex chemistry of the upper layers of the Venusian atmosphere simply cannot be explained by the presence of life as we know it.

After a group of scientists controversially announced that back in 2020 they had detected phosphine gas in the clouds of Venus. , assumptions about life in the clouds of Venus at moderate altitudes have become quite common.

But this idea is not new; indeed, biophysicist Harold Morowitz and astronomer Carl Sagan proposed the idea over 50 years ago, as early as 1967.

More recently, scientists have suggested that chemistry may hold clues – and that life in the clouds of Venus may have evolved a sulfur-based metabolism similar to what we’ve seen in microorganisms here on Earth.

The signature of the sulfur compound, sulfur dioxide (SO 2 ), is very peculiar on Venus: abundant at lower altitudes, but very low at higher altitudes.

“We’ve been trying for the past two years to explain the strange sulfur chemistry we see in the clouds of Venus,” says astronomer and chemist Paul Rimmer of the University of Cambridge.

“Life is pretty good at weird chemistry, so we were looking into whether there was a way to make life a possible explanation for what we see.”

As good as weird chemistry is, life as we know it isn’t very good. while hiding its existence, unless it is underground, or in a cave, or something like that.

Biological processes extract elements from their environment and release various elements into it. Breathing is a good example: we humans breathe in oxygen and breathe out carbon dioxide. (Trees take in carbon dioxide and give off oxygen, which is a good system.)

The chemical composition of Venus is very different from the Earth’s, the atmosphere is extremely rich in sulfur – its concentration is 100,000 times higher than on Earth. those in the Earth’s atmosphere are associated with compounds such as sulfur dioxide, sulfuric acid, and carbonyl sulfide.

So, in a new study, a team of researchers led by astronomer Sean Jordan of the University of Cambridge determined to investigate the chemical reactions we should expect given the available energy sources in Venus’s 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’s the main energy source available,” Jordan says.

“If this food is consumed by living things, we should see evidence of this in the fact that certain chemicals are lost and accumulated in the atmosphere. .”

Of particular interest was the strange signature of sulfur dioxide. Here on Earth, this compound is formed by volcanism, and it is possible that it is formed in the same way on Venus.

However, if organisms with sulfur-based metabolism lived in the upper atmosphere of Venus, they could be responsible for the unusual lack of sulfur dioxide at these altitudes.

Scientists have previously proposed a sulfur-based metabolism that could theoretically use chemicals present in Venus’s atmosphere.

Using these as a starting point, Jordan and his colleagues attempted to simulate the chemical reactions that would occur with these life forms to see if they create the observed composition of Venus’s atmosphere.

They found that the sulfur metabolization of life can lead to the observed depletion of sulfur dioxide; but the result of the metabolic processes of a biomass of the required size will produce other compounds in abundance, which, in short, simply do not exist.

“If life were responsible for the SO 2 we see on Venus, that would also destroy everything we know about Venus’ atmospheric chemistry,” Jordan says.

“We wanted life to be a potential explanation, but when we ran the models it wasn’t a viable solution. But if life isn’t responsible for what we see on Venus, that’s still a problem to be solved – there’s a lot of weird chemistry to trace.”

We still don’t. I don’t know how or why sulfur dioxide is released from the upper atmosphere of Venus, so it remains an open question. It’s also possible that there is a biosphere with an unknown metabolism that we won’t know about until a probe goes there to check it out. So it’s interesting.

In the meantime, the team says, their study offers a framework that could help model the impact of the aerial biosphere on alien worlds and thus look for life in exoplanet atmospheres. Given that exoplanet atmospheres are the best place to look for signs of life, this is really handy.

“Even if ‘our’ Venus is dead, it’s possible that Venus-like planets in other systems could host life,” says Rimmer.

“We can take what we’ve learned here and apply it to exoplanetary systems – this is just the beginning.”

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