A team of scientists modeling the Venusian atmosphere found data that could help explain the confusing chemistry in the planet’s clouds. The results advance the possibility of the existence of life in Venus’ atmosphere, an ever-controversial idea that will be explored by several planned missions to the burning planet.
Venus is the second planet from the Sun, making it much warmer than Earth. In addition to the planet’s heat, Venus is a dry, rocky wasteland dominated by volcanoes and toxic sulfuric acid clouds. That cloud layer – about 19 km thick – envelops the planet’s surface from terrestrial observers most of the time, and recently it has been in the spotlight as a possible hiding place for alien life.
Recent research modeled these clouds in greater depth, and the researchers found that the clouds on the planet are not fully composed of sulfuric acid, but have a certain amount of ammonium salt mixed in. The team’s study was published in the Proceedings of the National Academy of Sciences.
“Our model predicts that the clouds are not made exclusively of concentrated sulfuric acid, but that the cloud droplets are partially neutralized. Our model postulates that the compound that neutralizes the acid in the clouds is ammonia, ”said Janusz Petkowski, an astrobiologist at MIT and co-author of the recent study, in an email. “The source of ammonia is unknown, but may be the result of biological production of ammonia in cloud droplets. As a result of the neutralization of the acid, the clouds are no more acidic than some extreme terrestrial environments that contain life.”
The latest work is based on much-publicized research published last year in Nature, which claimed to detect phosphine gas in the Venusian atmosphere. (The researchers behind the new paper were also among the authors of the phosphine paper.) Phosphine is produced by microorganisms that do not need oxygen to survive, so the presence of the gas was a surprising, exciting sign that something biological could happen. in the clouds. The finding was controversial; other scientists have said that the presumed phosphine signal was really just sulfur dioxide, while others have suggested that active volcanoes, not life, could be responsible.
“No life we know of could survive in the Venus droplets,” Sara Seager, a planetary scientist at MIT and co-author of the new study, said in an institute release. “But the point is, there might be some life there, and it’s changing its environment so it’s habitable.”
The new paper did not focus on phosphine, but rather some inexplicable chemical signatures in Venus’ clouds. Year observations have indicated more water vapor and sulfur dioxide than expected. Ammonia, the researchers believed, could explain these anomalies.
“Ammonia should not be on Venus,” Seager added. “It has hydrogen attached to it, and there is very little hydrogen around. Any gas that does not belong in its environment is automatically suspicious of being made of life.”
The models indicated that if microorganisms were on Venus and produced ammonia, oxygen would be released as a by-product. Furthermore, the ammonia (which is alkaline) would neutralize the drops of sulfuric acid in the clouds, making them somewhat habitable. Although all of this work was done with models, future space probe emissions could help us get some answers about what’s really going on in the clouds.
These missions are NASA’s VERITAS and DAVINCI + missions, ESA’s EnVision orbiter and (perhaps) the proposed privately funded Venus Life Finder Missions that Seager and Petkowski are working on. The latter is the only one with the basic purpose of investigating the possibility of alien life on Venus, but the space agency’s missions are also likely to gather some information on the subject. Of these three, DAVINCI + is the only mission that will actually enter Venus’ atmosphere and test it as the spacecraft descends to the planet’s surface.
If life of any kind were found outside Earth – either petrified on the surface of Mars, thriving in the clouds of Venus or swimming in the ocean of an icy moon – it would be one of the most significant scientific discoveries ever. But there is a long, uncertain road ahead before such claims can be made.
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