Gas discovery could point to life on Venus, claim UK scientists
The discover y of phosphine gas in the clouds of Venus could possibly indicate signs of life on the planet, scientists have said.
The gas has been detected in the atmosphere of Venus, suggesting 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.
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.
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 fur ther obser vations and modelling are needed to explore the origin of the gas in the planet’s atmosphere.
Writing in the pap er, 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 add: “We emphasise that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry.”