The possibility of “life on Venus” was the most high-profile and controversial topic in astronomy last year. Now, astronomers’ conclusion can finally make some people “give up” – according to a new study published in the British magazine “Nature Astronomy”, the relative availability of water in the clouds of Venus and most planets in the solar system is too low, even if Life forms that have adapted to the extreme environments of the earth will also find it difficult to survive. The discovery also shows that most planetary environments with clouds are not conducive to life as we know it, but related research can help narrow the search for extraterrestrial life.
In September 2020, a major planetary scientific research project was announced. A team of British scientists detected phosphine gas in the atmosphere of Venus for the first time. At that time, the team believed that this discovery could indicate the existence of unknown photochemical or geochemical processes on Venus, but the detection of phosphine could not be used as strong evidence for the existence of microbial life. However, since the possibility of microbial life cannot be completely ruled out, and on Earth, phosphine is thought to be a gas produced by anaerobic organisms, the term “life on Venus” was proposed and widely used in many subsequent discussions. discuss.
Soon, the world was turning its attention to the nearby planet, with multiple scientific teams turning their instruments on Earth and in space to Venus, hoping to be the first to determine whether it heralds the possibility of life. Scientists believe that water activity, measured on a scale of 0-1, is equivalent to the relative humidity, or water availability, in a planet’s atmosphere. Water activity in the environment has a huge impact on organisms, including organisms called extremophiles that live in extreme environments. Laboratory studies show that life requires a water activity of at least 0.585 to metabolize and reproduce.
There is no possibility of life on Venus
With this in mind, a team including researchers from Queen’s University Belfast in the UK calculated in detail the limits on life from water activity in the clouds of Venus and other solar system planets. They found that sulfuric acid droplets reduced the water activity in Venus’ clouds to less than 0.004, less than one percent of what is needed to limit life. In comparison, the water activity in Martian clouds is 0.537, which is only slightly below the habitable range for life and close to the Earth’s second layer of atmosphere, the stratosphere. However, the lowest layer of the Earth’s atmosphere, the troposphere, is suitable for life. The research team also analyzed that the water activity of Jupiter’s atmosphere allows the existence of life, which is higher than 0.585, and the temperature ranges from -10%uB0C to +40%uB0C, but factors such as the composition of the clouds limit its habitability.
The scientists concluded that the method used in this study can also be applied to determine the water activity in the atmosphere of planets outside the solar system, thereby helping humans narrow the scope of the search for extraterrestrial life.