Scientists say the discovery of phosphine gas in Venus’ clouds could indicate signs of life on the planet.
Gas was found in the atmosphere of Venus, indicating that the planet may be undergoing unknown photochemical or geochemical processes.
On Earth, phosphine, a colorless gas that smells of garlic or rotten fish, is mainly produced by anaerobic biological sources.
Small amounts of gas naturally occur from the decomposition of organic matter.
Although the surface conditions of Venus, the second planet from the Sun, are hostile to living things, the environment of the cloud deck above it is temperate, 53–62 km (33–38 miles) from the surface.
According to a study published in Nature Astronomy, the formation of clouds is very acidic, in which case phosphine is destroyed very quickly.
Jane Greaves and colleagues from Cardiff University observed Venus in 2017 and 2019 with the James Clerk Maxwell Telescope and the Atacama Large Millimeter / Sublimeter Array.
They discovered a spectral signature unique to phosphine, and estimated that there are 20 parts to a billion phosphons in the clouds of Venus.
Professor Greaves said: “We discovered a rare gas called phosphine in the atmosphere of our neighboring planet, Venus.
“So there is a chance to find some kind of life in the clouds of Venus.”
The researchers examined various sources of gas production, including sources on the planet’s surface, micrometers, lightning, or chemical reactions within clouds.
But they could not determine the source of the phosphine levels.
However, they argue that the discovery of phosphine is not strong evidence of microorganisms and only refers to unknown geographical or chemical processes occurring on the planet.
They say more observations and modeling are needed to determine the origin of the gas in the planet’s atmosphere.
As they write in the paper, they say: “PH3 (phosphine) originates from unknown photochemistry or geochemistry, or from the presence of life, which is similar to the biological production of PH3 on Earth.”
They add: “If no known chemical reaction can explain pH3 in the atmosphere above Venus, it must be made by a process previously unreliable for the state of Venus.
“It could be anonymous photochemistry or geochemistry or maybe life.”
Is phosphine on Venus like methane is on Mars? About 20 parts per million of phosphine are found in the temperate clouds of Venus, the source of which is unclear. Greaves et al.: https://t.co/aZhuAXkNdZ pic.twitter.com/a3sFW6qXoS
– Nature Astronomy (ature Natural Astronomy) September 14, 2020
The researchers continue: “Even if confirmed, we say that the discovery of PH3 is not strong evidence for life, only for inaccurate and unexplained chemistry.
“The idea of life in the clouds of Venus has significant conceptual problems – the environment is extremely dehydrated and hyperosidic.
However, we rejected several chemical routes to PH3, almost four or eight orders down.
“Substantial modeling and experimentation is important to further distinguish between unknown photochemical and / or geological processes as the source of Venus ‘pH3, or to determine whether there is life in Venus’ clouds.
“Ultimately, a solution can be found by visiting Venus again for situ measurements or aerosol return.”
Massachusetts Institute of Technology scientist Dr. William Baines led the work to evaluate natural methods of producing phosphine.
Some concepts include sunlight, minerals rising from the surface, volcanoes, or lightning, but none of these can get close enough.
Dr. Baines said: “We do not claim to have life. We claim that there is something, it is really unknown, it may be life. ”
Alan Duffy, an astronomer at the University of Swinburne and associate professor at the Royal Institution in Australia, said: “The presence of extraterrestrial life is one of the most exciting signs I ‘ve ever seen. Amazing location I can imagine.
“Our twin planet Venus is a hellish world. Although the surface at which the lead melts is high, the temperature decreases as you ascend to the clouds and becomes like Earth at an altitude of 50 km in temperature and pressure, exactly where phosphine is found.
“When the temperature drops, the clouds contain sulfuric acid, which breaks down the phosphine so that it forms a new one, which makes us think that it could be life on Venus because phosphine is related to life on Earth.
“But before we can get more confident about it, we need to reject all other non-biological means of producing it.”