Venusians in the mist?

The search for life in our solar system has long been directed at Mars, with its icecaps and somewhat comparable conditions to Earth, it seemed like the logical (if not optimistic) place to look. However, for a long time, very little regard has been given to our neighbour on the other side; the second planet from the Sun, Venus. With surface temperatures that can reach up to  460 degrees C and an atmosphere consisting of 96% carbon dioxide and clouds of sulfuric acid, has long thought to be too inhospitable for life. But, earlier this week, an international team of astronomers and researchers, led by Professor Jane Greaves of Cardiff University at the University of Cardiff, had an opportunity to get some time on the James Clerk Maxwell Telescope (JCMT) in Hawaii, decided to point the telescope at Venus. 

“I thought we’d just be able to rule out extreme scenarios, like the clouds being stuffed full of organisms.”

 Professor Jane Greaves of Cardiff University and lead researcher of this project.

 To their surprise, they detected ….. higher concentrations of phosphine gas (PH3) in the atmosphere than they would have expected, in fact a very low concentration of phosphine gas, 10-20 parts per billion! Following these observations, Greaves and her team were awarded time to use telescopes at the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to confirm this observation, and the recordings from these specialised telescopes were then processed by Professor Hideo Sagawa of Kyoto Sangyo University to determine the presence of phosphine and at what levels. This discovery has now spread ripples of piqued curiosity across the world….. but why is everyone so excited?

Well, on Earth, phosphine is a compound that is highly associated with microbial life and is usually found in oxygen-poor biomes, such as swamps, as well as in the stomachs of certain animals, such as penguins. And, although phosphine can be created through some natural processes, such as volcanic activity, or after lightning strikes, it should quickly decompose in the acidic atmosphere. So to find levels, at even 10 parts per billion, was certainly a surprise to scientists. Something must be happening to maintain this concentration of phosphine, a process that is unexplainable through the current understanding of the abiotic processes which happen on Venus.  

However, it is feasibly that high in the Venetian clouds, where the air temperature is relatively more hospitable, there could be a bloom of extremophile bacteria, surviving in the harsh conditions and belching out phosphine gas into the atmosphere. We perhaps need to change our definition of what “hospitable” actually means, when it comes to observing other worlds.

“ Phosphine should not survive long among the acid and ultraviolet-bathed clouds. However, it could be produced by microbes suspended in the air, in the ‘sweet zone’ 50-60 km up where the temperature is cool enough for life, at a rate sufficient to match its rate of inorganic decomposition. “

Prof David Rothery, Professor of Planetary Geosciences at The Open University

So what does this mean; should we expect to find alien life soon? As exciting as this discovery may be, it is important not to conflate these findings. These observed levels of phosphine are certainly very curious and astronomers are currently unable to explain these recorded levels when considering the current understanding of the abiotic workings of the planet. But pinning an explanation on alien microbes at this moment in time would be irresponsible, as this would take some leaps in logic using only circumstantial evidence, as well as some wishful thinking. It may be tempting to speculate and be caught up in this exciting idea, but at this moment, we just do not know. But, maybe we will now will shift our attention from the red planet and renew our interest in our closest planetary neighbour.    

The full paper on this discovery can be found here.  

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