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Chemical Linked to Life Found in Cloud Decks of Venus

Orange image of the planet of venus
NASA/Jet Propulsion Laboratory-Caltech

Considering its surface temperature of 880°F, and an atmosphere consisting mostly of sulphuric acid, it might be hard to imagine Venus hosting life of any kind. But a recently described find might make thinking about Venusian life a little easier.

A Shock

Using the James Clerk Maxwell Telescope (JCMT) in Hawaii and the 45 telescopes of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a team of international scientists first spotted and then confirmed the presence of a rare molecule known as phosphine. On Earth, phosphine is made by certain microbes and from various industries such as those that make rat poison and some electronics. Because we’re pretty sure there are no factories on Venus, the team who spotted the phosphine molecules believes the source to be organic.

Professor Jane Greaves of Cardiff University says:

“This was an experiment made out of pure curiosity, really—taking advantage of JCMT’s powerful technology, and thinking about future instruments. I thought we’d just be able to rule out extreme scenarios, like the clouds being stuffed full of organisms. When we got the first hints of phosphine in Venus’ spectrum, it was a shock!”


Possible ways in which the molecules could be forming include natural processes such as lightning and volcanoes, or through the effect of sunlight or surface minerals floating up to the cloud decks where the phosphine molecules were found. But, say the researchers, none of these processes could account for the amount of phosphine they found—a relatively modest amount of about 20 molecules per billion. Yet microbes operating at only 10% of their maximum productivity could expel the amount of phosphine seen.

If such microbes did exist, they would undoubtedly be different than those found on Earth needing, for example, to be able to survive in the highly acidic environment of Venus’ clouds. Temperature-wise though, the upper atmosphere of Venus is much cooler than its surface, hitting daytime temps of around 98°F, so this could be a much more life-friendly climate.

“Finding phosphine on Venus was an unexpected bonus,” said team member Clara Sousa Silva from MIT. “The discovery raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about 5% of acid in their environment—but the clouds of Venus are almost entirely made of acid.”

The Self-Correcting Process

Of course, while the researchers were meticulous in confirming the presence of phosphine and in allowing their work to be scrutinized by their peers, they are quick to acknowledge that it is still too soon to believe life is floating in the clouds on Venus. They are waiting to get back to their telescopes to try to pinpoint the phosphine’s location in the clouds and to see if they can find any other gases associated with life.

Further information could come from the Japanese Akatsuki spacecraft, which is mapping Venus’ atmosphere, including its dark streaks which, some scientists have postulated, get their color from a concentration of microbes.

“This paper makes a strong case for the detection of phosphines in Venus’s atmosphere and that an unknown process is responsible for their generation—biological or otherwise,” said Casey Dreier, Chief Advocate and Senior Space Policy Adviser for the Planetary Society, who was not involved in the research. “But this is the start, not the end, of the discovery process. It may end up leading to the confirmation of life many years into the future. It may (perhaps more likely) end up establishing a novel natural pathway for generating phosphine in Venus’s atmosphere. The self-correcting process of science works at the group level—not on that of the individual. We will have a better sense of this claim in the next few years by looking at the community consensus after more data are collected, and more debate occurs.”

The paper has been published in the peer-reviewed journal Nature Astronomy.