Months after a study suggested the idea of life floating in the clouds of planet Venus, an international team of researchers led from Queen’s University Belfast, UK, has dismissed such a possibility. In the new study published in the journal Nature Astronomy, the researchers have said that the clouds are too dry for an active life.
The earlier study had pointed to the presence of phosphine, a molecule made up of one phosphorus atom and three hydrogen atoms, in the clouds to suggest that microbes might inhabit the Venusian atmosphere. On Earth, phosphine is often associated with life due to the presence of microbes in low-oxygen environments such as swamps.
The Belfast researchers assessed the conditions in the clouds of Venus that are mostly sulphuric acid with a tiny fraction of water. They looked for the known microbes that could survive in the most challenging conditions on Earth and concluded that such “extremophiles” would not be able to survive in clouds.
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The researchers devised a method to determine the water activity of atmospheres of a planet and found that the water activity was more than a hundred times below the lower limit at which life can exist on Earth.
“Our research shows that the sulphuric acid clouds in Venus have too little water for active life to exist, based on what we know of life on Earth. We have also found that the conditions of water and temperature within Jupiter’s clouds could allow microbial-type life to subsist, assuming that other requirements such as nutrients are present,” Dr John E. Hallsworth said.
On the other hand, the research shows that Jupiter’s clouds have a high enough concentration of water, as well as the correct temperature, for life to exist there. Dr Philip Ball, the co-author of the paper, noted that the search for extraterrestrial life has sometimes been a “bit simplistic in its attitude to water.”
“We’ve got to think too about how Earth-like organisms actually use it – which shows us that we then have to ask how much of the water is actually available for those biological uses,” he added.
Nasa and the European Space Agency (ESA) have just announced three new missions to Venus and one of these will take measurements of Venus’s atmosphere. Hallsworth said that his team will be able to compare those measurements with their findings.
