Astronomers have revealed that the discovery of phosphine gas in the clouds of Venus could possibly indicate 'signs of life' on the planet.
The gas has been detected in the atmosphere of Venus, which suggests the planet could host unknown photochemical or geochemical processes.
On Earth, phosphine – a colourless gas that has the smell of garlic or decaying fish – is produced predominantly by anaerobic biological sources.
Small amounts of the gas occur naturally from the breakdown of organic matter.
While the conditions on the surface of Venus – the second planet from the Sun – are hostile to life, the environment of its upper cloud deck, around 53–62km (33-38 miles) above the surface, is temperate.
Where was the study published?
But according to the study, published in Nature Astronomy, the make-up of the clouds is highly acidic, and in such conditions phosphine would be destroyed very quickly.
Who made the discovery?
Jane Greaves, from Cardiff University, and colleagues observed Venus with the James Clerk Maxwell Telescope and the Atacama Large Millimeter/submillimeter Array in 2017 and 2019, respectively.
They detected a spectral signature that is unique to phosphine, and estimated an abundance of 20 parts-per-billion of phosphine in Venus’s clouds.
Researchers looked at different ways the gas may have been produced, including from sources on the surface of the planet, micrometeorites, lightning, or chemical processes happening within the clouds.
But they were unable to determine the source of the trace quantities of phosphine.
However, they argue that the detection of phosphine is not robust evidence for microbial life and only indicates potentially unknown geological or chemical processes occurring on the planet.
They say further observations and modelling are needed to explore the origin of the gas in the planet’s atmosphere.
Writing in the paper, they say: “PH3 (phosphine) could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH3 on Earth, from the presence of life.”
They add: “If no known chemical process can explain PH3 within the upper atmosphere of Venus, then it must be produced by a process not previously considered plausible for Venusian conditions.
“This could be unknown photochemistry or geochemistry, or possibly life.”
The researchers continue: “Even if confirmed, we emphasise that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry.
“There are substantial conceptual problems for the idea of life in Venus’s clouds – the environment is extremely dehydrating as well as hyperacidic.
“However, we have ruled out many chemical routes to PH3, with the most likely ones falling short by four to eight orders of magnitude.
“To further discriminate between unknown photochemical and/or geological processes as the source of Venusian PH3, or to determine whether there is life in the clouds of Venus, substantial modelling and experimentation will be important.
“Ultimately, a solution could come from revisiting Venus for in situ measurements or aerosol return.”
What have astronomers said about the discovery?
Associate Professor Alan Duffy, an astronomer from Swinburne University and the lead scientist of The Royal Institution of Australia, said: “This is one of the most exciting signs of the possible presence of life beyond Earth I have ever seen, and certainly from the most surprising location I could imagine.
“Our twin planet Venus is a hellish world. While the surface is hot enough to melt lead, the temperature drops as you go higher into the clouds, becoming Earth-like in both temperature and pressure by an altitude of 50km, exactly where the phosphine was found.
“While the temperature is benign the clouds contain sulfuric acid which should break down the phosphine, so something is forming it anew, and as phosphine is associated with life on Earth it is tempting to think it could be life on Venus.
“But before we can become more confident about that we have to rule out all possible other non-biological means of producing it.”
Why are you making commenting on The National only available to subscribers?
We know there are thousands of National readers who want to debate, argue and go back and forth in the comments section of our stories. We’ve got the most informed readers in Scotland, asking each other the big questions about the future of our country.
Unfortunately, though, these important debates are being spoiled by a vocal minority of trolls who aren’t really interested in the issues, try to derail the conversations, register under fake names, and post vile abuse.
So that’s why we’ve decided to make the ability to comment only available to our paying subscribers. That way, all the trolls who post abuse on our website will have to pay if they want to join the debate – and risk a permanent ban from the account that they subscribe with.
The conversation will go back to what it should be about – people who care passionately about the issues, but disagree constructively on what we should do about them. Let’s get that debate started!
Callum Baird, Editor of The National
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article