Traces of a rare molecule known as phosphine have been found in Venus’ cosmic, highly acidic atmosphere, astronomers said Monday – providing a striking indication of the possibility of life. The phosphine molecules found on Earth are mainly the result of human industry or the actions of microbes that thrive in oxygen-free environments.
Researchers do not claim to have identified life on the second planet from the sun. But the observations show at least the possibility of microbial activity in the upper layers of Venus’ atmosphere, far from the inhospitable surface of the planet.
“We have detected a rare gas called phosphine in the atmosphere of our neighboring planet Venus,” said Jane Greaves, a professor at Cardiff University in the United Kingdom and co-author of a report published in Nature Astronomy. “And the reason for our excitement is that phosphine gas on Earth is produced by microorganisms that live in oxygen-free environments. And so there is a possibility that we have spotted some kind of living organism in Venus’ clouds.”
However, the team said, much more study is needed to support any such claim, as excellent as it would be.
“To make this extremely amazing claim that there can be life there, we really have to rule everything out, and that is why we are very careful in saying that we are not claiming that there is life, but that there is something that is really unknown and can is life, “said teammate William Bains, a researcher at MIT.
Sara Seager, a fellow MIT scientist studying the exoplanet’s atmosphere, agreed, saying “we do not claim to have found life on Venus.”
“We claim the confident detection of phosphine gas, the existence of which is a mystery,” he said. “Phosphine can be produced by certain (non-biological) processes in Venus, but only in such incredibly small quantities is not enough to explain our observation. So we are left with this other exciting, enticing possibility: that there may be some kind of life in the clouds of Aphrodite. “
Mars has long been considered the best candidate in the solar system beyond Earth to have hosted microbial life in the distant past or even in the present, as methane levels suggest. NASA, the European Space Agency, China, India, Russia and the United Arab Emirates continuein one form or another.
NASA is also planning a flagship mission to study it. Scientists believe that one of the largest and most famous moons on the planet, , warmed by tidal pressures and gravitational interactions with other moons, hosts a salty, possibly habitable ocean beneath its icy crust. Other frozen moons in the outer solar system, the possible “water worlds”, are also candidates for study.
However, Venus is the victim of a greenhouse effect in which dense clouds in a carbon dioxide atmosphere mainly trap sunlight, producing surface temperatures that rise to almost 900 degrees, hot enough to melt the lead.
In the upper atmosphere of the planet, however, temperatures are much more hospitable. Despite the acidic nature of the clouds, scientists have speculated that foreign germs may be present.
“The surface conditions there today are really hostile, the temperature is high enough to melt our unloaders,” Greaves said. “But it is believed that much earlier in Aphrodite’s story the surface was much cooler and wetter and life could possibly have originated.
“There is a long-standing theory that some of the smaller life forms could evolve up into the high clouds. The conditions there are certainly not nice, they are extremely acidic and they are very windy, but on the other hand, if you are talking about 50 to 60 kilometers above, then the pressure is very similar to the Earth’s surface and the temperature is quite nice, maybe up to about 85 degrees Fahrenheit. Therefore, it is assumed that this is a living habitat today. “
The Greaves team studied spectra of Venus’ atmosphere using the James Clerk Maxwell Telescope in Hawaii and 45 telescope antennas in the Atacama Large Millimeter / submillimeter series in Chile and were surprised to see unmistakable signs of phosphine. “It was a shock,” Greaves said.
The detection was rewarded with extra observation time in the ALMA series and “in the end, we found that both observatories had seen the same thing, attenuated absorption at the right wavelength to be phosphine gas, where the molecules are illuminated by the warmer clouds below.” Greaves said in a statement.
Only traces were observed, about 20 molecules per billion. But additional research has shown that natural sources of phosphine – volcanoes, lightning, metals in the atmosphere, the action of sunlight – will produce only one-tenth of a millimeter of the amount actually detected.
The group may rule out many non-biological ways of generating observed phosphine levels, but that does not mean that life is the only explanation. Venus’ atmosphere is 90% sulfuric acid, raising “many questions, such as how any organism could survive,” said MIT researcher Cara Sousa Silva.
“On Earth, some germs can withstand up to about 5% acids in their environment, but Venus’ clouds are almost entirely made of acid,” he said.
The Greaves team is waiting for extra telescope time to look for signs of other gases related to biological activity and to determine the temperature of the clouds where phosphine is present to obtain additional information. Eventually, future spaceship visits will probably be needed to fully resolve the issue.
“There may always be something we overlooked,” Seager said. “Ultimately, the only thing that will answer this question for us – is there life, there is no life – actually goes to Venus and makes more detailed measurements for signs of life and perhaps for life itself.”