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An international group of astronomers announced today that a rare molecule, phosphine, has been discovered in the clouds of Venus. On Earth, this gas is only produced industrially and by microbes that live in an oxygen-poor environment. Astronomers have long speculated that high-altitude clouds on Venus may harbor microbes because they can float in the upper atmosphere to avoid the scorching heat from the surface, while at the same time having to withstand the extremely acidic environment. The detected phosphine may also be a sign of such floating alien life forms.
“When we first saw the phosphine signs in the spectrum, we were shocked!” Begins Jane Greaves, head of the UK Cardiff University research team, who was the first to trace phosphine through her observations with the James Clerk Maxwell (JCMT) binoculars at the East Asian Observatory on the island. from Hawaii. To confirm the discovery, 45 antennas from the high-sensitivity Atacama Large Millimeter / Submillimeter Array (ALMA) microwave telescope network were needed in partnership with the European Southern Observatory (ESO) in Chile. Both instruments observed Venus in the wavelength range of about one millimeter, wavelengths much larger than light visible to the human eye, which can only be detected effectively with binoculars operating at high altitudes.
Measurements by an international group of researchers in the United Kingdom, the United States, and Japan show that phosphine is only present in extremely low concentrations in the clouds of Venus; There are only twenty of them out of a billion molecules. After the observations, the researchers performed calculations to see if this amount could come from natural and non-biological processes on the planet. These can be the effects of sunlight, minerals emanating from the surface, volcanic activity, or lightning. But far from any process it is capable of producing the detected concentration. All these non-biological processes can be responsible for up to ten thousandths of the amount observed with radio telescopes.
The research team estimates that producing phosphine from hydrogen and phosphorous at the concentration detected on Venus would require only 10 percent of the total capacity of terrestrial organisms. We know that some terrestrial bacteria produce phosphine. They convert phosphate and hydrogen extracted from minerals or biological sources into phosphine. Even if there are microorganisms that operate such biochemical processes on Venus, they are certainly very different from their Earth counterparts, but they are still conceivable as sources of atmospheric phosphine.
Although the discovery of phosphine in the atmosphere of Venus surprised everyone, the researchers are confident in the results of their measurements. “To our great delight, the conditions for perceiving ALMA were appropriate when Venus was in the correct position for Earth. However, data processing has been a challenge because ALMA rarely detects such a small signal in a celestial body as bright as Venus, ”Anita Richards, member of the ALMA UK Regional Center and the University of Manchester, presents in detail technicians. “Ultimately, we found that both instruments saw the same thing: the faint absorption line for phosphatase at exactly the expected wavelength, in the light emitted by deeper, warmer clouds,” adds Greaves, lead author of a paper in Nature Astronomy.
Clara Sousa Silva, another member of the research team at Massachusetts University of Technology (MIT) in the United States, has previously studied the applicability of phosphine as a biomarker, a compound that can reveal biological processes in oxygen-free environments of exoplanets that they orbit distant stars. This gas is a good biomarker precisely because very little is produced from it through natural processes. “It was an unexpected surprise to discover phosphine on Venus! The result immediately raises several questions, such as how an organism can survive there. Some microbes on Earth can tolerate up to 5% acid in their environment, but the clouds on Venus are essentially made up entirely of acids! Sousa Silva turns it on.
The researchers believe they have made a significant discovery, as they have been able to rule out a number of alternative possibilities for phosphine formation. At the same time, they acknowledge that much work will still be needed to prove the presence of life on Venus. Although the clouds floating in the upper atmosphere of the planet have a pleasant temperature of 30 degrees Celsius, the environment is extremely acidic, consisting of approximately 90% sulfuric acid, posing a serious challenge for any microbes that intend to survive there. .
“Based on our current chemical knowledge of phosphine and the atmosphere of rocky planets, we can rule out the non-biological origin of the compound on Venus. Demonstrating the presence of life in the atmosphere of Venus would be a breakthrough in astrobiology. For this reason, it is essential to continue with this research, both theoretically and observationally, to rule out the possibility of phosphine formation in rocky planets of shapes other than Earth ”, adds Leonardo Testi, ESO astronomer and ALMA director of European activities. in this research.
Any future observations of Venus and extraterrestrial rock planets, such as the extremely large binoculars being built at ESO, could provide additional clues to the origin of phosphine and aid investigation of extraterrestrial life.
Source: ESO
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