Could there be life on Venus? The second planet from the Sun is the hottest planet in our Solar System, which rules out the possibility of life on its surface. Not only does the planet have a surface temperature of around 425°C but it also has an atmospheric pressure 90 times that of Earth.
However, some scientists have long speculated that Venus' upper atmosphere could be host to so-called extremophiles, organisms that can survive in extreme environments. Now scientists at MIT and Cardiff University discovered signals of phosphine in the atmosphere of Venus. After ruling out all other possible explanations, the team concludes the phosphine detected in Venus' clouds could only have been produced by a living organism there.
The phosphine gas was found in the cloud deck of Venus, a band within Venus' atmosphere, between 48 and 60 kilometres above the surface. This layer of the planet's atmosphere has previously been identified by scientists as possibly habitable by extremophiles.
The MIT team followed up the new observation with an exhaustive analysis to see whether anything other than life could have produced phosphine in Venus’ harsh, sulfuric environment. Based on the many scenarios they considered, the team concludes that there is no explanation for the phosphine detected in Venus’ clouds, other than the presence of life.
“It’s very hard to prove a negative,” says Clara Sousa-Silva, research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “Now, astronomers will think of all the ways to justify phosphine without life, and I welcome that. Please do, because we are at the end of our possibilities to show abiotic processes that can make phosphine.”
“This means either this is life, or it’s some sort of physical or chemical process that we do not expect to happen on rocky planets,” adds co-author and EAPS Research Scientist Janusz Petkowski.