An international scientific team, with the participation of the Spanish Astrobiology Center (CAB), has shown that the activity of the water in the clouds of Venus presents values that are well below the range of habitability of the most extreme terrestrial organisms and this limits in greatly the possibility of life in the atmosphere of one of the most Earth-like planets.
For a year, the detection of phosphine in its atmosphere has rekindled scientific interest in Venus because the presence of this gas could indicate the existence of some kind of microbial life in the clouds of this “twin” planet of the Earth.
However, new research that has calculated the presence of water in these clouds has significantly reduced this possibility, because the water activity detected does not allow survival in the clouds of Venus or of terrestrial organisms that endure the most severe conditions. extreme.
And this study is important, because all microorganisms need the presence of water, in an available form, in order to grow and carry out their metabolic functions.
As María Paz Zorzano, a CAB researcher and co-author of this research, points out, “the study shows that there is so much sulfuric acid in the clouds that the water moves and the water activity is too low for life to exist, at least as that we know. In other words, the clouds of Venus are not habitable. “
In addition, the conclusions of this new research are very interesting, because, after the announcement of the phosphine detection, both NASA and ESA (the European Space Agency) have announced that they will send three new space probes to Venus, at the end of this decade, to be able to demonstrate whether or not there is some kind of life in the clouds of this planet, which today is a real hell.
Specifically, an international scientific team, in which the Center for Astrobiology (CAB) participates, has calculated the activity of the water within the clouds of Venus, and other planets of the Solar System, from observations of temperature and abundance of steam from Water.
The results are published today in the journal Nature Astronomy. The value obtained for the water activity of the sulfuric acid droplets, which make up most of the clouds on Venus, is ≤0.004, two orders of magnitude below the 0.585 limit for known extremophiles.
The study has been extended to other planets, such as Mars, where the formation of water ice imposes a water activity of ≤0.537, slightly below the habitable range. Or the clouds of Jupiter, where the conditions are biologically permissive (> 0.585) although other factors, such as their composition, can play an important role in limiting their habitability.
The approach used in the present study is of great importance for the future as it can also be applied to the habitability of extrasolar planets.
In fact, María Paz Zorzano concludes that “it is not enough to detect traces of water and a temperature above 0 ° C for an environment to be habitable. It is necessary that there is enough water so that, at this pressure and temperature, the microorganisms can metabolize and reproduce ”.