Venus does not have enough water in its clouds to sustain life

In 1978, NASA launched the Pioneer Venus mission, which consisted of an orbiter and a team of four small probes thrown into the atmosphere of Venus. Inside the atmosphere, there were signs of deuterium, a heavy hydrogen isotope that can cause water breakdown. Scientists wondered if Venus could ever have more water and some stuck in larger amounts in the atmosphere.

Until 2020 and potential detection traces of phosphine In the atmosphere of Venus. These scientists he envisioned a scenario in fact, a potential cycle of water in high clouds of Venus sulfuric acid can allow Venus microbes to be present in high-altitude droplets and create spores that hydrate and maintain a reproductive life cycle. Although the surface of the planet is hell, its clouds are stable and warmer.

Well, the new paper means that this is very difficult. The study is the amount of water that can be used by “water activity” or microorganisms, measured on a scale of 0 to 1. For this study, the research team tried to measure the activity of cloud water by calculating the relative atmosphere. humidity (the amount of water that saturates the air at a given temperature). It has been used by scientists Aspergillus penicillioides, a fungus that is able to live in some of the driest conditions imaginable, while being able to perform and reproduce metabolic functions as a basis for understanding how much water an organism can withstand. The answer is a score of 0.585 water activity, as we know it is the “life limit” of biological activity.

Using atmospheric data collected from past Venus missions and using newer models to evaluate water activity, Hallsworth and his team calculated the water activity of Venus clouds at an altitude of 68-42 km, where life-tolerant temperatures range from -40 ° C to 130 ° C. ° C. They found that water activity, at best, is 0.004. “The driest tolerant microbes on Earth would have no chance on Venus,” says Hallsworth.

The researchers also noted that even if the water activity itself is higher, Venus’s atmosphere is full of cellular elements, which would likely prevent the cellular system from functioning properly (e.g., sulfuric acid dehydrates cells).

Other planets did better. The group also estimated that water activity in Mars was 0.537 (equivalent to the Earth’s stratosphere and below the “life limit” in Earth’s life), and that at least 0.585 in Jupiter’s clouds is between -10 ° C and 40 ° C. “We can’t say that Jupiter’s clouds are capable of living,” says Christopher McKay, a NASA scientist and author of the study. “We can say that water activities are not limited.”

The findings need to be confirmed with further research, but the authors are confident that they will not change, even more so Two new NASA missions and a new ESA mission headed to Venus at the end of the decade.

Of course, there are some remarks. “We need to take what we know about life on earth as a basis for discussions based on life in other worlds, because we have the basis for that,” McKay says. “But part of me hopes that when we find life in other places, it’s going to be very, very different,” with biochemistry that transcends the boundaries of what we’ve seen here on Earth.

And while the current life on Venus seems unlikely with these new discoveries, it doesn’t mean that Venus was always sterile. The history that scientists want to investigate is hidden on the planet.