Life on Venus claims crumble but Jupiter holds promise
The roiling clouds around Jupiter may not look hospitable to life, but appearances could be deceiving, a team of researchers say about the potential for biological development elsewhere in our solar system. The new study, digging deep into just what key factors are required for life to be sustained, also casts doubt over another possible location that had been tipped as a potential incubator.
Life, as we know it at least, has some common denominators, and big one is the presence of water. Indeed the hunt for water – whether liquid, gaseous, or ice – elsewhere in the universe is a key part of humanity's search for either life, or other planets or bodies that might be at least conducive to life.
According to researchers at the School of Biological Sciences at Queens University, Belfast, however, there's more to it than just how much water is there. Instead, it's the effective concentration of water molecules present, they suggest. For that reason, while Jupiter may hold promise, Venus' fulsome clouds may be out of luck.
"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," Dr John E. Hallsworth, lead author on the research, said of the findings. "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."
In fact, Venus' sulphuric acid clouds have water activity more than a hundred times below the sort of limits that life can survive at on Earth. It counters suggestions researchers made last year, that evidence of phosphine gas in Venus' atmosphere could be a sign of life there. A paper on the new findings has been published today in Nature Astronomy.
It's an important distinction, because the current hunt for evidence of life takes a fairly basic approach. "As our work shows, it's not enough to say that liquid water equates with habitability," Dr Philip Ball, co-author of the study, adds. "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."
On Mars, for example, ice formation means water activity is slightly below the habitable range, the scientists calculate. Unsurprisingly, Earth's conditions are generally biologically permissive, though the atmosphere grows too dry for active life above the middle stratosphere.
"While our research doesn't claim that alien (microbial-type) life does exist on other planets in our solar system, it shows that if the water activity and other conditions are right, then such life could exist in places where we haven't previously been looking," Dr. Hallsworth concludes. The team has also demonstrated that the calculations can be used with more distant planets, outside of our own solar system.