Ural Federal University: Venus Clouds Probably Have Microorganisms

Scientists have suggested the theory of the existence of microorganisms on Venus. According to the hypothesis, microorganisms can be found in the cloud layer of Venus in a special econiche, which is a water-foam structure. The existence and development of microorganisms is helped by the temperature suitable for some Earth-type microorganisms. Researchers proved the possibility of such aqueous-foam structures in the laboratory and described them in the journal Life.

Today, conditions on the surface of Venus (temperature +470 ° C and pressure of 90 atmospheres) are unsuitable for terrestrial life forms. However, it is believed that millions of years ago Venus may have been inhabited. As it heated up and reached a critical temperature (+100 °C) on the planet’s surface, the entire volume of water evaporated, forming clouds 20-25 km thick. Together with water masses into the clouds could also move extremophilic microorganisms, which are able to survive at temperatures of +100 ° C and above.

“Most likely, as the surface temperature of Venus increased, there was a direct selection of microorganisms. The desiccation of water bodies with a significant temperature increase was accompanied by a strong increase in salt concentration. Before the catastrophic climate change on Venus, all species of extremophilic microorganisms occupied corresponding ecological niches. Then the “ecological comfort zone” for extremophiles expanded. As the temperature increased above +100 °С, the entire volume of water evaporated and together with water-soluble organic and inorganic compounds was transported into the cloud layer. The same ascending streams of hot water vapor could transport both active viable microorganism cells and spores into the clouds”, explains Yulia Khrunyk, a researcher of the Laboratory of Structural Methods of Analysis and Properties of Materials and Nanomaterials of the Ural Federal University.

The evaporation of water from the planet’s surface must have been accompanied by the formation of abundant clouds at altitude, where water vapor could have cooled and condensed, the scientists suggested. Most likely, the level of acidity of the formed clouds was initially close to neutral, so various microorganisms could thrive in them. Then, when the atmosphere of Venus lost most of its water, with a simultaneous acidification of the environment due to the formation of sulfuric acid molecules (with a constant influx of volcanic sulfuric gas), the selection of organisms was directed toward resistance to a strongly acidic environment.

“After full evaporation of water from the planet’s surface, further heating of Venus from +100 °С to more than +400 °С could be accompanied by dust storms, thermal decomposition of organic and inorganic materials and their active transfer to the atmosphere due to ascending air currents. In addition, at the beginning of overheating products of decomposition of dead biomass on the surface of the planet could pass with water vapor to the water phase inside the clouds and become a source of various organic nutrients. Thus, a community of microorganisms could form, which further adapted to the constant acidification of the environment (pH decrease)”, explains Yulia Khrunyk.

To survive under harsh conditions, microbes in the Venusian clouds occupied a specific niche in the liquid phase, where dissolved nutrients needed by the cells are most efficiently transported, the researchers claim. Unlike aerosols, this water-foam structure allows microbial cells to efficiently interact throughout the ecological niche space, which is very important for the stable existence of such a microbial system.

“A good example of stable water foam formation is boiling milk. Protein and fat molecules stabilize the bubbles that form from the air dissolved in the milk. Such foam is quite stable even when the temperature drops. We assumed that the foam structure in Venusian clouds formed under similar conditions, especially if it is stabilized by biosurfactants, is governed by the same principles,” explains Yulia Khrunyk.

According to Oleg Kotsyurbenko, Professor of Yugra State University, extremophile bacteria living in extreme terrestrial conditions (for example, in hot springs with low pH) will help to unravel the mystery of life on Venus. Therefore, scientists plan to study their survival in conditions similar to those on Venus, as well as to study specific molecules – biomarkers, which may be found during the study of the cloud layer in future space missions to Venus. Also, to answer the question of whether there is life on Venus, will help data from the spacecraft, which under the joint program Roscosmos-NASA are planning to launch in 2028-2030.

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