A possible sign of life in the clouds of Venus

The clouds on Venus may well contain phosphine, a gas associated with life on Earth, according to a British study based on the observation of two radio telescopes. This discovery is a first and arouses enthusiasm in the scientific community.

Scientists have determined the “obvious presence” in the cloud layers of Venus of a gas associated with life on Earth. This discovery, led by an astronomer at Cardiff University in the UK, was published on Monday, September 14 in the journal Natural astronomy.

This is the first time this compound has been discovered in one of the four terrestrial planets in our solar system, “the earth apart”, Jane S. Greaves, professor of astronomy and lead author of the article, told AFP.

Phosphine was detected by observing the Venusian atmosphere with two radio telescopes. It “may come from unknown processes in photochemistry or geochemistry, or, analogously to the biological production of phosphine on earth, due to the presence of life,” the study explains.

“It’s time to put Venus first”

This compound is found in the huge gas planets of the solar system, such as Saturn, but it is not of biological origin, that is, living. Traces of phosphine in the Earth’s atmosphere, on the other hand, come exclusively from human or microbial activity.

“Life on Venus? The discovery of phosphine, a by-product of anaerobic biology, is the most important event to date in the search for extraterrestrial life,” said Jim Bridenstine, administrator of NASA. “It’s time to prioritize Venus,” he said as research assignments from past lives focus on Mars today.

For Professor Alan Duffy, an astronomer at Swinburne University in Australia, the discovery is “one of the most exciting signs I have ever seen of the possible presence of extraterrestrial life.”

The presence of phosphine, a highly toxic compound, does not match the sacred atmosphere of the other planet closest to the sun. Also known as Shepherd’s Star, its atmosphere of carbon dioxide, at 97%, bathes at a surface temperature of about 470 ° C with a pressure that is more than 90 times higher than ours.

But it is in the thick layer of hyper acidic clouds, which cover the planet up to about 60 km altitude, that Jane Greave’s team assumes that the phosphine molecules can be found. “There, the clouds are” temperate “around 30 degrees Celsius”, according to the study, which does not rule out that the gas is formed at a lower and warmer altitude before rising.

A “small” way of life

But where does it come from? Jane Greaves “hopes to have taken into account all the processes that may explain her presence in the atmosphere of Venus”. If you do not identify a new one, the hypothesis of a way of life remains. If so, “we think (this life form) should be small to flow freely,” says the researcher, whose study “insists that the detection of phosphine is not a robust evidence of life, only of an abnormal and inexplicable chemistry.”

Phosphine consists of one atom of phosphorus and three of hydrogen. Phosphorus is one of the six chemical elements in living things, but “even if a planet contained an abundance of phosphorus, it may lack another state necessary for life, such as other elements, or its environment may be too hot, or too dry, warns Jane Greaves.

A priori, the atmosphere of Venus, “extremely dehydrating and hyper sour”, does not contribute to life. But maybe its cloud layer can be. NASA also discovered a decade ago microbial life in the upper layers of the Earth’s atmosphere.

That is why Prof. Greaves and her colleagues are calling for further observation of the phenomenon. Ideally free from the “filter” of the Earth’s atmosphere, thanks to a space telescope. And why not with another visit, by probe.

With AFP