A paper released on Monday, 14 September, showed the detection of a mysterious molecule called phosphine in the clouds of Venus. Researchers say that molecule could be produced by living microbial cells.
Speaking at a press conference, the team stressed that they had not found life on Venus.
Still, the news has sparked both excitement and doubt across the scientific community:
Chris Lintott, an astronomer based at the University of Oxford, said in a thread on Twitter: "Firstly, I'm told there has been much skepticism, including from journal referees, about the detection [of phosphine].
"[The telescopes used] were not made to look at things as bright as Venus and this is a difficult observation.
"However, we have detections from two separate telescopes, and the team who led the data reduction – Jane Greaves and Anita Richards – know [the telescopes] very well. I'd bet the detection is real."
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Astrophysicist Becky Smethurst says the astronomers "spent three years thinking about every other possible process that could explain this – volcanoes, lightning, sunlight triggering the formation – but none of those could produce enough phosphine.
"Hence why now they’re publishing this work with a big question mark – LIFE?"
Anita Richards, one of the team behind the discovery, toldBBC Science Focus: "At the moment, we can't explain how enough phosphine molecules could survive long enough in the Venus cloud decks to allow us to detect it."
What is phosphine?
"Phosphine is made up of one phosphorous molecule with three hydrogen molecules," explains Richards. "It is much less stable than water – it would not stand a chance in the very acid atmosphere of Venus unless it was being frequently replenished. The Venus experts and chemical experts on our team say that there is no known way that this could be done."
But, says Richards, one thing that would produce a mixture of gases, is life.
"Even microbes have cell walls and indeed can get energy and nutrients from imbalances like this. We have no idea if this is what is going on – but at the moment it seems less impossible than other explanations."
So what kind of life could be responsible?
The Royal Astronomical Society says that any microbes on Venus will likely be very different to their Earth cousins, as they would have to survive in hyper-acidic conditions.
Dr Arik Kershenbaum, who recently speculated what aliens might look like in his book The Zoologist’s Guide to the Galaxy,toldBBC Science Focus: "This isn’t just a huge indication that there might be alien life literally next door to us. It’s also a big wakeup call for rethinking how we look for life in the universe.
"Phosphine would be a sign of a biochemistry very different from the ones we know from life on Earth. Looking for life with a metabolism “like us” is too narrow a search. We might not have much in common chemically with alien life.
"Even if our biochemistry is so very different, one mechanism we can be confident we *do* share with any oxygen-shunning organisms on another planet is that we both achieved the complexity of life through natural selection. We didn’t just pop into existence, and neither did they. Thinking about how such life could *evolve*, and become complex, is the next big challenge for astrobiologists.
"Hopefully Venus will prove to be home to its own kind of life, but if it turns out not, then there are still millions of other possibilities in the Galaxy, and the principles of natural selection will apply there too."
What next?
"The first step is to try and repeat the observations of Venus, and improve the techniques in light of our experiences. Unfortunately, that is not straightforward," says Richards. "Venus has to be at the right orientation to the Sun and Earth and the right distance so it appears not too big and not too small.
"Both [the telescopes used in this discovery] are affected by COVID restrictions... We will apply for time as soon as possible!
"In the short term, we can also make more observations with space missions that are orbiting, or planned to orbit or fly by, Venus. This work is already underway. For the future we will need specialised missions to visit Venus to conduct observations of phosphine and other chemicals and, potentially, to dip into the clouds and examine this environment directly.
"A life-finding mission could use a microscope to directly search for cellular life. A sample return mission, bringing back samples from the cloud decks would be ideal, but we are a long way from such a mission."
