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A possible indicator of the presence of life in the clouds of Venus has been identified: it is phosphine, or hydrogen phosphide, a gas that on Earth is produced only industrially or by microorganisms in oxygen-free environments. The discovery, published in the journal Nature Astronomy, is from the group of astronomers at the British University of Cardiff, coordinated by Jane Greaves. The phosphine fingerprint was captured by the James Clerk Maxwell Telescope (JCMT) in Hawaii and by the Alma antennas of the Southern Europe Observatory (ESO).
According to the study authors, phosphine, a molecule made up of one phosphorus and three hydrogen atoms, is found in the clouds of Venus at a low concentration: only about twenty molecules per billion. After the observations, the astronomers tested whether these quantities could come from natural non-biological processes on Venus, such as those induced by sunlight or in minerals pushed up from the surface, volcanoes, or lightning strikes. However, none of these phenomena, experts point out, is currently capable of producing enough phosphine. In fact, the authors calculated that these non-biological sources produce at most one ten thousandth of the amount of phosphine seen by telescopes.
For John Robert Brucato, exobiologist at the National Institute of Astrophysics (Inaf), “phosphine has its value in the search for life in space: it could, in fact, be the trace of the presence of some microorganism that produces phosphine as waste . In the Earth’s atmosphere – adds the academic from INAF – phosphine is produced by microorganisms that use phosphate minerals, through redox processes. This molecule on Venus should quickly degrade and disappear due to the extreme conditions present on the planet, such as very high atmospheric pressure and temperatures of more than 450 degrees near the ground. The fact of having found it suggests, therefore, that there may be a continuous production of phosphine ”.
What researchers are now asking is what is the origin of this molecule. “It can come from microorganisms or abiotic processes, that is to say geological or geophysical”, explains Brucato. “But to date, there are no known abiotic processes from which phosphine can originate, so the discovery is interesting. It is a kind of alarm bell – he concludes – that may suggest the presence of some form of life in the Venusian atmosphere “. where the temperature is significantly lower than that of the ground “.
