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(CNN) – A gas present on Earth was also detected in the atmosphere of Venus. The “completely surprising” discovery of phosphine could hint at unknown processes occurring on Earth’s “twin” planet.
Phosphine suggests the presence of life on Earth. And the idea of aerial life in the clouds of Venus is intriguing. But it is not likely.
On Earth, phosphine is a toxic, foul, and flammable gas produced by bacteria that do not require oxygen, such as those in swamps, wetlands, mud, or even the guts of animals. Its smell has been compared to rotting fish or garlic. It can also occur when organic matter breaks down.
The atmospheric conditions of Venus
Venus is similar in size to Earth and is often referred to as Earth’s twin, but in reality it is not.
Venus is an unusual planet that scientists are still trying to understand. It is our closest planetary neighbor, but it rotates backwards compared to other planets. The planet’s thick atmosphere helps trap heat, and its surface is hot enough to melt lead.
Above its hot surface, which is 482.2 degrees Celsius, the upper layer of clouds that is between 53 and 60 kilometers above the planet’s surface is much warmer. But the clouds on Venus are very acidic, which should quickly destroy phosphine. So how did it get there?
“Something completely unexpected and highly intriguing is happening on Venus that produces the unexpected presence of small amounts of phosphine gas,” Sara Seager, study co-author, astrophysicist and planetary scientist at the Massachusetts Institute of Technology, said in an email.
The study, written by Cardiff University professor Jane Greaves and her colleagues, was published Monday in the journal Nature Astronomy.
Researchers used the James Clerk Maxwell Telescope in Hawaii in 2017 and the Atacama Large Millimeter / submillimeter Array in 2019 to study Venus. Their data revealed a unique spectral signature for traces of phosphine in the planet’s atmosphere. Scientists estimated that 20 parts per billion of gas is present in the clouds of Venus.
The research team considered surface sources such as volcanoes, lightning, delivery via micrometeorites, or chemical processes that occur in clouds as potential causes. But they couldn’t determine how the phosphine was produced.
NASA’s Mariner 10 spacecraft captured this view of Venus shrouded in dense global cloud cover.
How did this substance get to Venus?
The researchers were left with pretty extreme possibilities, Seager said.
“(One possibility) is that an unknown chemistry is occurring in the atmosphere, surface, or subsurface of Venus,” he said in an e-mail statement. ‘We found this explanation difficult to accept due to Venus’ temperature and pressure range, and the fact that the planet has almost zero hydrogens means that 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 modeling to show why the gas is present in the atmosphere. And a potential future mission that could sample clouds and the surface may also shed light on the source.
However, there is a possibility that this phenomenon is an indication of chemical or geological processes occurring on Venus that have not yet been discovered or are not believed to be possible under the conditions of Venus.
Earlier, a 2019 study, of which Seager authored, suggested that phosphine may act as a biological signature for life if detected in “tremendous amounts” on rocky exoplanets. This large amount could be at a cumulative level that future telescopes, such as NASA’s James Webb Space Telescope, could detect.
Phosphine
“Phosphine on Earth does not exist outside of the production of life because, like on Venus, the Earth’s environment is not very favorable for the production of phosphine,” Seager explained. “Because Venus is so close and bright, our study found much smaller amounts than is expected to be necessary on an exoplanet.”
However, studying the atmospheres of rocky planets in our solar system provides a key test bed for trying to understand the atmospheres of exoplanets or planets outside our solar system, and whether they could support life.
The research team will continue their search for the origin of the phosphine gas detected on Venus, as well as looking for other unexpected gases in its atmosphere.
The discovery of phosphine on Venus raises it to an area of interest worth exploring in our solar system alongside the ranks of Mars and “waterworld” moons like Enceladus and Europa, Seager noted.
“Our expected impact on the planetary scientific community is to stimulate more research on Venus itself, research on the possibilities of life in the atmosphere of Venus and even space missions focused on finding signs of life or perhaps life itself in the atmosphere of Venus” Seager commented.
