A team of researchers has put forward a new theory suggesting possible life on the planet Venus could be making the environment more hospitable.
Published in the journal Proceedings of the National Academy of Sciences, the team from Cardiff University in Wales, MIT in Cambridge, Mass., and Cambridge University in England say potential life may be creating its own habitable environment in the clouds of Venus through a "cascade of chemical reactions," which in turn may also explain other "strange anomalies" that have puzzled scientists for decades.
Among those puzzling questions has been the presence of ammonia, a gas that was "tentatively" detected in the 1970s, and which the team says by all accounts shouldn't be produced through any chemical process known on Venus — the second planet from the sun after Mercury and before Earth.
Simply put, the group says: "Life could be making its own environment on Venus."
"We know that life can grow in acid environments on Earth, but nothing as acid as the clouds of Venus were believed to be," William Bains of Cardiff University's School of Physics and Astronomy, and a co-author of the study, said in a news release.
"But if something is making ammonia in the clouds, then that will neutralize some of the droplets, making them potentially more habitable."
The scientists note that certain life forms on Earth have the ability to produce ammonia in order to neutralize and make an otherwise highly acidic environment livable.
As part of their work, the researchers modelled a set of chemical processes to show that if ammonia is present on Venus, the gas would set off a series of chemical reactions, neutralizing surrounding droplets of sulfuric acid.
The pH level of the clouds, or how acidic or basic they are, would then increase from roughly -11 to 0, the team says. While still very acidic, the researchers say this would be within the range of acidity that life could tolerate.
The team also tested whether dust could be sweeping minerals into the clouds of Venus and causing them to interact with the sulfuric acid.
However, it was determined that a massive amount of dust would be needed, which led the team to consider ammonia.
If life were producing ammonia, the researchers say the associated chemical reactions would naturally yield oxygen, which has been identified as one anomaly on the planet.
Once ammonia is in the clouds, it would dissolve in droplets of sulfuric acid and effectively neutralize it, creating a salt-like slurry.
The most plausible explanation for where ammonia would originate from, the researchers hypothesize, is biological, as opposed to a non-biological source such as lightning, volcanic eruptions or even a meteor strike.
"Ammonia shouldn't be on Venus," study co-author Sara Seager from MIT's Department of Earth, Atmospheric and Planetary Sciences said.
"It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."
The group says a set of proposed privately funded missions, called the Venus Life Finder Missions, of which Seager is principal investigator, could serve as an opportunity to check for the presence of ammonia — and signs of life — in the next several years.
"There are many other challenges for life to overcome if it is to live in the clouds of Venus," Bains adds.
"There is almost no water there for a start, and all life that we know of needs water. But if life is there, then neutralizing the acid will make the clouds just a bit more habitable than we thought."
