Venus, with its sulfuric acid clouds and hellish surface temperatures, is often ignored as a potential abode for life. But some planetary scientists have suggested that atmosphere-dwelling microbes could survive in its lower cloud layers, possibly explaining Venus’ mysterious atmospheric phenomena. The cloud layers in question — hovering roughly 30 to 37 miles (48 to 60 kilometers) above Venus’ sweltering surface — feature arguably livable temperatures, nutrients, and even a bit of water dissolved inside droplets of sulfuric acid.
Now, a team led by Sara Seager, an astrophysicist at the Massachusetts Institute of Technology (MIT), proposes a hypothetical life cycle for how microbes might survive in Venus’ atmosphere. The researchers claim they are the first to hypothesize a specific mechanism by which organisms could persist in the venusian haze and cloud layers, rather than being rained down and destroyed by the fiery surface conditions below. The team outlines how venusian microbes could cycle through the different layers of the atmosphere, surviving the most extreme conditions by transitioning into a dormant state.
The new research was published August 13 in Astrobiology.
Microbes in the clouds of Venus
Cloud-borne microbes are not unprecedented in the solar system. “On our own Earth, we also have what we call an aerial biosphere,” Seager tells Astronomy. “[Microbes] from Earth get upswept and they float around. They get inside droplets and the wind carries them across entire continents and oceans.”
Seager explains that, over time, the water droplets housing microbes in Earth’s atmosphere condense, growing larger and heavier. And eventually, they fall down to the surface. But falling from Venus’ clouds would almost certainly be lethal to any microbes, as the planet’s blistering surface temperatures reach more than 860 degrees Fahrenheit (460 Celsius).
“So, the question we posed was, ‘Well, how does it live permanently in the clouds?” says Seager.