A team of researchers including experts who discovered phosphine on Venus in 2020 believe that micro-organisms could exist on the planet, "creating" a habitat for themselves.
Venus is an extremely inhospitable place, not just for humans, but for life in general. Its atmosphere is saturated with carbon dioxide, the pressure on the surface is similar to that on Earth at a depth of 900 meters under the water column, while the average temperature is 462 degrees Celsius. The planet is shrouded in a dense cloud of sulphuric acid.
Nevertheless, some scientists believe that certain types of living organisms may exist at least in the conditions of the Venusian clouds. After all, microbes live in the Earth's atmosphere, bituminous lakes, hot springs, extremely acidic or oxygen-free environments. Such organisms are called extremophiles, and under certain conditions they could probably live on Venus as well.
After phosphine gas, a potential marker of life, was discovered on this planet, the debate over its presence or absence has not ceased. Many studies show there is no phosphine on Venus and the conclusions presented in Nature Astronomy on 14 September 2020 by a team of scientists from the Massachusetts Institute of Technology (USA) and Cardiff University in Wales (UK) are wrong.
But some of the same scientists (including those from Massachusetts, Cardiff and Cambridge Universities) involved in the discovery of phosphine have decided to look at the problem from a different angle and have published the results of a new study in the journal PNAS. They identified a chemical pathway by which life would neutralise the acidic environment of Venus by creating a self-sustaining habitable pocket in its clouds.
In addition to phosphine, the Venusian clouds are known to contain ammonia, as well as other chemical compounds that would not seem to form naturally on this planet. The presence of life would explain the existence of such compounds in the planet's atmosphere, so looking towards such a hypothesis is a very tempting idea.
There is, however, an opinion that such substances may be formed by dust, which is carried away from the surface of Venus into the clouds, where its particles react chemically with sulfuric acid. This would explain the presence of certain compounds in the atmosphere, but not all of them. Also, in this case, the amount of dust lifted from the surface must be very large.
Scientists modelled a number of chemical processes in search of an answer. As it turned out, if the clouds of Venus do exist microorganisms that produce ammonia in adequate quantities (found in the Venusian atmosphere, as mentioned above), then the associated chemical reactions would naturally produce oxygen as well.
In addition, the ammonia would neutralise the sulphuric acid, making the clouds more habitable. Thus, the researchers were able to explain the presence of ammonia and some other substances and compounds in the atmosphere of Venus, which, in theory, should not be there.