Gas find on Venus clouds suggests sign of life
A gas on Earth has also been detected in the atmosphere of Venus. The "entirely surprising" discovery of phosphine could hint at unknown processes occurring on Earth's "twin."
Phosphine suggests the presence of life on Earth. And the idea of aerial life in the clouds of Venus is intriguing. But it's not likely.
On Earth, phosphine is a flammable, foul, toxic gas produced by bacteria that doesn't require oxygen - like those in swamps, wetlands, sludge or even animal guts. Its odour has been likened to decaying fish or garlic. It can also occur when organic matter breaks down.
READ MORE: Astronomers see possible signs of life on Venus clouds
Venus is similar in size to Earth and often referred to as Earth's twin, but it's not really.
Venus is an unusual planet that scientists are still trying to understand. It's our closest planetary neighbour, but it spins backward compared to other planets. The planet's thick atmosphere helps to trap heat, and its surface is hot enough to melt lead.
Above its hot surface, which is 480 degrees, the upper cloud deck that's 80km above the planet's surface is much more temperate. But Venus' clouds are very acidic, which should quickly destroy phosphine. So how did it get there?
"Something completely unexpected and highly intriguing is happening on Venus to produce the unexpected presence of tiny amounts of phosphine gas," said Sara Seager, study coauthor and astrophysicist and planetary scientist at Massachusetts Institute of Technology, in an email.
The study authored by Cardiff University professor Jane Greaves and her colleagues published Monday in the journal Nature Astronomy.
Researchers used the James Clerk Maxwell Telescope in Hawaii in 2017 and the Atacama Large Millimetre/submillimetre Array in 2019 to study Venus. Their data revealed a spectral signature unique to traces of phosphine in the planet's atmosphere.
The scientists estimated 20 parts-per-billion of the gas is present in Venus' clouds.The research team considered surface sources like volcanoes, lightning, delivery via micrometeorites or chemical processes occurring in the clouds as potential causes. But the scientists weren't able to determine how the phosphine was produced.
The researchers were left with rather extreme possibilities, Seager said."(One) is that some unknown chemistry is occurring in the Venus atmosphere, surface, or subsurface," she said in an email statement.
"We find this explanation tough to accept because (of) Venus's temperature and pressure range and the fact that Venus has nearly zero hydrogens mean(s) phosphine is not the natural form of the element phosphorus. Instead phosphorus should be present as phosphates."
Future observations could reveal the source, as well as modelling to show why the gas is present in the atmosphere. And a future potential mission that could sample the clouds and surface may also shed light on the source.
However, it could be an indication of chemical or geological processes occurring on Venus that haven't been discovered yet or thought possible under the conditions on Venus.