Even though it is the closest neighboring planet to Earth, Venus is not necessarily welcoming. Life as it is known on the blue planet is impossible there, for lack of enough water in its atmosphere, according to a study published Monday in Nature Astronomy. This is a new rebuttal to that of scientists on the detection of a gas possibly linked to living things.
“There is no possible active life” in the clouds of Venus, said microbiologist John Hallsworth, lead co-author of the study. The neighbor of the Earth resembles it however in many respects, by its size and its mass, but is distinguished from it by an infernal surface temperature, 470 ° C, and an atmosphere of carbon dioxide at 97%. In other words, not very conducive to life.
Scientific debates on phosphine
The planet is also covered with a thick layer of clouds made up of droplets of sulfuric acid. It was in this that last September, the British astronomer Jane Greaves announced the discovery of phosphine. This compound coming, on Earth, from human or microbial activity, the announcement had put the scientific community in turmoil, before being vigorously contested by specialists.
This time the objection comes to the very possibility that a living organism could exist under such conditions. One of the subjects of study by John Hallsworth of Queen’s University, Belfast, is “the minimum amount of water that microbes [les plus résistants] can be satisfied on Earth to stay active and develop ”. His judgment is final: the amount of water available in the clouds of Venus is “more than a hundred times too low” for the survival of the most resilient microorganisms known. In other words, “at an insurmountable distance from what life requires to function”.
Pr. Jane Greaves’ team has finally lowered the amount of phosphine it claims to have detected. For Chris McKay, NASA astrophysicist and co-author of Monday’s study, “there is no firm consensus in the scientific community that the signal detected is phosphine.” But even if there is, we know enough about the atmosphere of Venus to “tell if there is enough water for life,” according to Chris McKay. And “on Venus this is not the case, and by far”.
New explorations around 2030
For this NASA expert, the three probes that will explore Venus around 2030 will confirm the temperature, pressure and water measurement data already acquired, while also making it possible to retrace the history of this neighbor “who could be habitable. three billion years ago ”. But could the Star of the Shepherd, as it is called, harbor a different form of life than the ones we know? To this “philosophical” question, Chris McKay replies that then, “we leave biology (…) and enter the realm of the imagination”. Space also has a part of dreams.