Science & Technology

Venus might have microbial life in its atmosphere, study shows

Phosphine gas, made up of hydrogen and phosphorus, hass been found in the planet’s clouds, a marker for the existence of microbes that can live without oxygen

By Akshit Sangomla
Published: Monday 14 September 2020

Venus might have microbial life in its atmosphere that could be the first sign of extra terrestrial life in our solar system, in fact anywhere in our observable universe, according to a new study.

An international team of astronomers from United States (US), United Kingdom (UK) and Japan announced the discovery of phosphine gas, made up of hydrogen and phosphorus, in the planet’s clouds, that is a marker for the existence of microbes that can live without oxygen.

Though the organisms would be a little far away from the super hot surface of the planet, they would have to be tolerant of the highly acidic atmosphere of Venus.

“When we got the first hints of phosphine in Venus’s spectrum, it was a shock,” Jane Greaves of Cardiff University in the UK, also the team leader of the study, said.

“Finding phosphine on Venus raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about five per cent of acid in their environment — but the clouds of Venus are almost entirely made of acid,” Clara Sousa Silva of the Massachusetts Institute of Technology in the US, said.

The research published in the journal Nature Astronomy on September 14 estimated that phosphine gas occurs in trace amounts in the planet’s atmosphere — only about 20 molecules for every billion.

Astronomers made the initial observations by using the James Clerk Maxwell Telescope (JCMT), operated by the East Asian Observatory in Hawaiʻi. They later used a more sensitive telescope called the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to further confirm their observations.

“Both facilities observed Venus at a wavelength of about 1 millimetre, much longer than the human eye can see — only telescopes at high altitude can detect it effectively,” according to the European Southern Observatory, which is part of the ALMA project.

After their observations about the concentration of the phosphine gas got confirmed, the scientists calculated if the gas could have been produced by non- biological processes like sunlight, volcanoes or lightning but later decided that none of them could have produced the gas even in those trace amounts.

To produce phosphine gas in that quantity living organisms would have work at 10 per cent of their maximum productivity. The bacteria on Earth that generate phosphine ingest phosphate from minerals or other biological material, combine it with hydrogen to produce energy for their sustenance and eject phosphine gas as a by-product.

The researchers do warn that any form of life if it is indeed floating currently on Venus would be very different from the bacteria on our home planet. Further, they are also pretty confident of their findings.

“To our great relief, the conditions were good at ALMA for follow-up observations while Venus was at a suitable angle to Earth. Processing the data was tricky, though, as ALMA isn’t usually looking for very subtle effects in very bright objects like Venus,” Anita Richards, team member of the UK ALMA Regional Centre and the University of Manchester, said.

“In the end, we found that both observatories had seen the same thing — faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below,” Greaves added.

But even then, other scientists want more observations before confirming that biology is the only way that phosphine can be produced on Venus.

For instance, Leonardo Testi, an astronomer at ESO, who was not involved with the study, said that “the non-biological production of phosphine on Venus is excluded by our current understanding of phosphine chemistry in rocky planets' atmospheres. Confirming the existence of life on Venus's atmosphere would be a major breakthrough for astrobiology; thus, it is essential to follow-up on this exciting result with theoretical and observational studies to exclude the possibility that phosphine on rocky planets may also have a chemical origin different than on Earth.”

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