Scientists are confident that solving the biological mysteries of Venus is only possible with the help of an in situ mission
Venus, our hot and mysterious «sister» planet continues to excite the minds of scientists. In 2020, the discovery of phosphine in its atmosphere renewed discussions about the possibility of life on this planet. Despite the fact that further research could not confirm the presence of phosphine, interest in Venus did not fade away. A detailed study of chemical anomalies in the atmosphere confirms that Venus may harbor biological processes.
One of the authoritative researchers in the field of astrobiology, Janusz Petkowski, proposes sending a mission to study this mysterious planet. He notes that for many years scientists have been wondering about the possibility of life on Venus. The temperature and pressure in the atmosphere of Venus are close to terrestrial conditions, which indicates the potential suitability of the planet for habitation.
The atmosphere of Venus is extremely thick and hot. It consists primarily of carbon dioxide, but also contains nitrogen and clouds of sulfuric acid. However, other chemicals are present only in trace amounts, — they are present in small quantities, which are insignificant in comparison with the main components of the atmosphere.
Of particular interest to scientists is the region of the atmosphere of Venus, located at an altitude of 48 to 60 kilometers above the surface of the planet. Here the pressure and temperature are close to those on Earth. It is here that conditions can be found that allow water to exist in a liquid state. The likelihood of liquid water in the atmosphere of Venus indicates the planet's potential habitability.
The authors of the new article note that in addition to the phosphine discussed, Venus hides a number of mysteries. One of these riddles — «unknown UV absorber». Back in the 1920s, researchers discovered unusual contrasting characteristics in the upper cloud layers of Venus: something absorbs ultraviolet light in a certain range of wavelengths. Despite many studies, scientists have not yet been able to identify the substance responsible for this absorption.
Scientists are actively working on this mystery and offering different hypotheses. It is assumed that allotropes and different forms of existence of sulfur, in which the atoms are organized differently, play a key role. However, these assumptions are based on simulated studies and have not yet received experimental confirmation.
Despite the fact that Venus has been explored for more than half a century with the help of orbital missions such as Venus Express and Akatsuki, many mysteries have still not been solved. Studying the atmosphere of Venus could be an important step in understanding the planet's potential for life and perhaps even finding traces of biological processes.
Meanwhile, despite decades of effort and observations by ESA's Venus Express and JAXA's Akatsuki spacecraft, none of the proposed candidate molecules matched the observational data exactly. These molecules either fit the profile poorly or are in short supply, and some proposed candidates are unstable.
It is important for scientists to understand what causes this unusual absorption of UV radiation, which accounts for more than 50% of the solar energy reaching Venus and affects its atmospheric structure and dynamics. This mystery represents a large gap in knowledge about the planet and hinders the understanding of its nature.
Some researchers suggest that this unknown UV absorber may indicate biological activity in the clouds of Venus. The spectral characteristics of Venus's clouds, including strong absorption of UV radiation, are consistent with the spectrum of some species of terrestrial bacteria.
Another mystery relates to the composition of particles in the lower cloud layers of Venus: it is not known what they are made of, and why some have a non-spherical shape. The presence of these non-spherical particles was confirmed by NASA's Pioneer Venus mission. Since these particles cannot be liquid droplets, it is assumed that they may be associated with life forms. However, the data disproves the possibility that the aforementioned atmospheric sulfur is present in the form of sulfuric acid in these particles, further deepening the mystery.
Some scientists object to the existence of such large particles and believe that the detection may be due to errors in the calibration of the research instrument. But to solve this mystery, an astrobiological mission is required. Programs using research instruments will be able to provide direct measurements and answers to these questions.
The atmosphere of Venus hides other mysterious components. It contains traces of gases with unusual profiles that scientists today cannot explain. For example, the discovery of oxygen causes a lot of controversy and no answer as to how it could have appeared in the atmosphere of Venus.
Venus research presents a real challenge because many observations can be interpreted as the result of biological and abiotic processes. This is why it is so important for scientists to conduct an astrobiological mission.
The authors of the article emphasize the need for new in situ missions to study the biological potential of Venusian clouds. Many scientists share this view, including renowned planetary scientist Sarah Seager. She even suggests sending a sample return mission to get more detailed information.
Several mission projects to Venus are already planned in the future, such as NASA's VERITAS mission and the DAVINCI mission. However, their approval, preparation and dispatch will take several years. The DAVINCI mission is proposed to conduct observations of the atmosphere of Venus, and the VERITAS mission will make detailed mapping of the planet's surface.
Currently, scientists are working with limited data. Despite the persistence in studying observational data, they are not enough to answer questions, but to generate more and more riddles that excite the minds. Therefore, the only thing that all scientists agree on is — is that a full-fledged mission to Venus, entirely devoted to studying its biology and chemistry, can solve the mysteries of this planet.