Categories: Astronomy

Life Could Make Habitable Pockets in Venus’ Atmosphere

The tantalizing possibility that life exists in the clouds of Venus is once again causing a stir amongst planetary scientists this week. Researchers out of the Massachusetts Institute of Technology, Cardiff University, and the University of Cambridge have proposed that some longstanding ‘anomalies’ in the composition of Venus’ atmosphere might be explained by the presence of ammonia. But ammonia itself would be a strange compound to discover there, unless some unknown process – such as biological life – was actively producing it. Perhaps more intriguingly, ammonia can remove the acidity from Venus’ hostile cloud-tops, suggesting that an airborne, ammonia-producing microbe might have evolved the ability to turn its hostile surroundings into something habitable.

Venus, a planet known for its inhospitable surface temperatures and pressures, along with sulfuric acid rain (that boils off before it can even reach the surface) and a runaway greenhouse effect, seems an unlikely place to look for life. Almost certainly, the planet’s surface is barren of anything we might recognize as ‘alive’. But it just might be possible that something could have evolved to live amongst the Venusian clouds, where pressures and temperatures are more manageable. Over the years, observers have noticed that Venus’ atmosphere contained elements it shouldn’t: most recently in 2020, when the discovery of phosphine suggested a biological microorganism might be actively producing the gas, which would quickly degrade without an ongoing source. Follow-up studies tempered the excitement about phosphine somewhat, suggesting there was not as much of it as originally thought, but its origin nevertheless remains an open question.

This latest study, which will appear in the Proceedings of the National Academy of Sciences, has nothing to do with phosphine, yet once again suggests the possibility of Venusian microbes floating in the planet’s atmosphere.

As Sara Seager, one of the paper’s co-authors, explains, “The phosphine detection ended up becoming incredibly controversial, but phosphine was like a gateway, and there’s been this resurgence in people studying Venus.” Those researchers began combing through past data, turning up more anomalies, and creating models that might explain them.

Artist’s conception of an aerial biosphere in the cloud layers of Venus’ atmosphere. Figure credit: J. Petkowska/MIT.

These anomalous chemicals include nonspherical particles (sulfuric acid usually produces round droplets), oxygen, and ammonia (NH3), a gas that should be nearly impossible to produce from the components available on Venus.

“Ammonia shouldn’t be on Venus,” Seager explained. “It has hydrogen attached to it, and there’s very little hydrogen around. Any gas that doesn’t belong in the context of its environment is automatically suspicious for being made by life.”

Abiotic processes don’t seem capable of producing ammonia on Venus, and yet it’s pretty clear that it’s there. Both American and Soviet missions to Venus have detected it (like Venera 8 and Pioneer), confirming its presence with at least some degree of certainty.

What’s more, the presence of ammonia in the clouds of Venus suggests that life there, if it exists, has evolved to change its environment and make it more livable. Ammonia would neutralize sulfuric acid, turning Venus’ nasty, inhospitable atmosphere into a cozier home for the organism producing it. “No life that we know of could survive in the Venus droplets,” Seager suggests, “but…maybe some life is there, and is modifying its environment so that it is livable.”

There are other possibilities, of course. Perhaps dust and minerals from the surface might be thrown into Venus’ atmosphere, creating many of the anomalies observed. But there is little evidence that there are enough eruptions, meteorite impacts, or other similar events to explain the anomalies completely. For the moment, no hypothesis seems as feasible as the biological one.

Of course, this is just a hypothesis, and will require in-situ testing to prove. If there really is something alive on Venus that has evolved to change its environment, we’re going to have to go there to find out.

Between NASA and ESA, there are three planned Venus missions in the coming decade, each of which might offer a little more insight into what’s going on in the clouds above our seemingly inhospitable neighbor. Privately funded missions may join them too. It’s impossible to say what they’ll find when they get there, but the possibilities are growing more intriguing.

Learn More:

Bains, W., Petkowski, J. J., Rimmer, P. B., & Seager, S. (2021). Production of Ammonia Makes Venusian Clouds Habitable and Explains Observed Cloud-Level Chemical Anomalies. Proceedings of the National Academy of Sciences.

Jennifer Chu, “Could acid-neutralizing life-forms make habitable pockets in Venus’ clouds?” MIT News.

Scott Alan Johnston

Scott Alan Johnston is a science writer/editor at the Perimeter Institute for Theoretical Physics, and a historian of science. He is the author of "The Clocks are Telling Lies," which tells the story of the early days of global timekeeping, when 19th-century astronomers and engineers struggled to decide how to organize time in a newly interconnected world. You can follow Scott on Twitter @ScottyJ_PhD

Recent Posts

Dust Devils and Strong Winds Produce the Constant Haze on Mars

Dust is an everyday feature on Mars and wreaks havoc on various pieces of equipment…

17 hours ago

Giant Sunspot AR3038 has Doubled in Size and is Pointed Right at Earth. Could be Auroras Coming

Sunspots are typically no real reason to worry, even if they double in size overnight…

21 hours ago

Remember That Rocket That was Going to Crash Into the Moon? Scientists Think They've Found the Crater

The Lunar Reconnaissance Orbiter (LRO) – NASA’s eye-in-the-sky in orbit around the Moon – has…

21 hours ago

Supernovae Were Discovered in all These Galaxies

The Hubble space telescope has provided some of the most spectacular astronomical pictures ever taken.…

23 hours ago

VY Canis Majoris is Dying, and Astronomers are Watching

Three-dimensional models of astronomical objects can be ridiculously complex. They can range from black holes…

24 hours ago

NASA Funds the Development of a Nuclear Reactor on the Moon That Would Last for 10 Years

If NASA's Artemis project to return to the Moon permanently is going to succeed, it…

1 day ago