A new model of water activity on different planets in the solar system has found that Venus would be too dry for even the most extreme life forms here on Earth, but there is good news: there may be other contenders in our solar system that we had not considered that they could host it.
There is no life on Venus
The study, led by Queen’s University of Belfast, analyzed data from several scientific probes, including Galileo, sent to different planets in the solar system. From these values, the scientists were able to calculate water activity, the pressure of water vapor within individual molecules in clouds, which is one of the limiting factors for the existence of life on Earth. They found that there is more than 100 times less water available in the atmosphere of Venus than is necessary for any organism to survive . And it is that despite the great similarities of Venus with Earth, it has a surface temperature of about 464 ° C and a pressure 92 times greater than that of our planet.
“When we looked at the effective concentration of water molecules in those clouds, we found that it was a hundred times lower for even the most resistant terrestrial organisms to survive,” explains microbiologist John Hallsworth, leading the work. “That is an insurmountable distance.”
Coincidentally, NASA is sending out two new missions to investigate Venus, which could give us a better understanding, at least, of whether this inhospitable world could ever have been habitable. What we know now is that it is too dry for terrestrial-like organisms to survive.
When planetary scientists search for life in other parts of the cosmos, they search for water because it is essential for life to survive. At least life as we know it. In September 2020, astronomers announced the detection of an excessive amount of phosphine gas in the upper atmosphere of Venus and, therefore, the possibility of life on Venus was tempting, since at altitudes of around 48 kilometers, there is a layer on Venus where temperatures and pressures are much more comfortable, and could potentially harbor clouds of microbes. This idea has been officially discarded after these new findings.
“The search for extraterrestrial life has at times been a bit simplistic in its attitude towards water,” says Philip Ball, a co-author of the study. “As our work shows, it is not enough to say that liquid water equals habitability . We also have to think about how Earth-like organisms actually use it, which shows us that we then have to ask how much water is actually available for those biological uses. “
There is definitely no possibility of life on Venus, but the work has yielded an unexpected discovery: Jupiter, the largest planet in the solar system, could be a new search option. In the clouds of Jupiter. The researchers say that some Jovian regions may even have the right temperature, but other factors, such as the composition of the gas itself, can limit any potential habitability.
According to experts, the methods used in their study can also be used to determine water activity in the atmospheres of planets beyond the solar system and help narrow the search for extraterrestrial life.
Referencia: Hallsworth, J.E., Koop, T., Dallas, T.D. et al. Water activity in Venus’s uninhabitable clouds and other planetary atmospheres. Nat Astron (2021). https://doi.org/10.1038/s41550-021-01391-3
