Venus’ atmosphere bears no signs of microbes eating or pooping, suggesting that the strange chemical composition of the planet’s clouds cannot be explained by extraterrestrial life.
In a new study, researchers have analyzed the biochemistry of thick sulfur-rich Venusian clouds that have fascinated scientists for decades. They looked for “fingerprints” that any potential organism living in the clouds would leave there as a result of their feeding and excretion.
“We’ve spent the past two years trying to explain the strange sulfur chemistry we see in the clouds of Venus“said Paul Rimmer, atmospheric scientist at the University of Cambridge in the United Kingdom and co-author of the study, in a statement (opens in a new tab). “Life is pretty good at weird chemistry, so we investigated if there’s a way to make life a potential explanation for what we see.”
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The researchers modeled the chemical reactions expected in Atmosphere of Venus, which is rich in sulfur dioxide. Sulfur dioxide concentrations are high in clouds closer to the planet’s surface but decrease with altitude. Scientists thought the sulfur dioxide might disappear as it was eaten by cloud creatures. When the researchers ran the models, however, they found that chemically that assumption didn’t work.
“If life were responsible for the levels of sulfur dioxide we see on Venus, it would also shatter everything we know about Venus’ atmospheric chemistry,” said Sean Jordan, an astronomer at the University of Cambridge and first author of the article, in the press release. “We wanted life to be a potential explanation, but when we ran the models it wasn’t a viable solution.”
The models simulated the metabolic reactions that atmospheric microbes would use to produce energy from food sources and generate waste. The results suggest that although these microbes can suck some of the sulfur dioxide from the clouds, this process would produce large molecules that were not detected.
“We looked at the sulfur-based ‘food’ available in the Venusian atmosphere – it’s not something you or I would want to eat, but it’s the main source of energy available,” Jordan said. “If this food is consumed by life, we should see evidence of it in specific chemicals lost and gained in the atmosphere.”
The researchers said that while the study did not produce the results they hoped for, it does provide valuable insight into the atmospheric chemistry of alien planets, and the methodology developed for this study could be used to search for life in outside the solar system.
“Even if ‘our’ Venus is dead, it’s possible that Venus-like planets in other systems could harbor life,” Rimmer said. “We can take what we’ve learned here and apply it to exoplanetary systems – this is just the beginning.”
In particular, the researchers said, the findings could guide observations of James Webb Space Telescopewhich is expected to reveal its first science images next month, as the telescope is able to detect such chemical fingerprints in distant atmospheres exoplanets.
Now that life doesn’t seem to be the answer to Venus’ strange atmospheric chemistry, scientists still have a lot of work to do to explain what’s really going on in these thick, sulfur-rich clouds.
The study was published June 14 in the journal Nature Communication (opens in a new tab).