Hot enough to melt metals and surrounded by a toxic atmosphere, Venus is among the most hostile places in the solar system.
But astronomers have reported the discovery of two gases that could indicate the presence of life forms lurking in the clouds of Venus.
The findings, presented Wednesday at the National Astronomy Meeting in Hull, add to evidence for a caustic gas, phosphine, whose presence on Venus has been hotly debated.
A separate team has reported a preliminary detection of ammonia, which on Earth is produced mainly through biological activities and industrial processes and whose presence on Venus, scientists say, cannot be easily explained by known atmospheric or geological phenomena.
The so-called biosignature gases are not evidence of extraterrestrial life. But the observation will heighten interest in Venus and raise the possibility that life arose and flourished in the planet’s more benign past and persists to this day in pockets of its atmosphere.
Scientists study life in Venus’ clouds
“Could Venus have had a warm, wet period in the past, after which global warming began to take its toll? [η ζωή] “They have evolved to survive in the only place they have left, which is in the clouds,” said Dr Dave Clements, an astrophysicist at Imperial College London, at the meeting.
Venus’ surface temperature is about 450 degrees Celsius, hot enough to melt lead and zinc, the atmospheric pressure is 90 times that of Earth’s, and there are clouds of sulfuric acid. But about 50 kilometers above the surface, the temperature and pressure are closer to those on Earth—and perhaps almost habitable for hardy microbes.
On Earth, phosphine gas is produced by microbes in oxygen-deficient environments, such as badger guts and penguin droppings.
The claim of discovering phosphine on Venus in 2020 was followed by controversy after subsequent observations failed to replicate the result. The latest observations by Clements and colleagues using the James Clerk Maxwell Telescope (JCMT), located in Hawaii, aim to resolve the controversy. By tracking traces of phosphine over time, they were able to strengthen the evidence for the gas’s presence, finding that its detection appears to follow the planet’s day-night cycle.
“Maybe it’s chemistry we don’t understand, or life.”
“Our results suggest that when the atmosphere is exposed to sunlight, phosphine is destroyed,” Clements said. “All we can say is that phosphine is there. We don’t know what produces it. It could be chemistry we don’t understand. Or it could be life.”
In the second lecture, Professor Jane Greaves, an astronomer at Cardiff University, presented preliminary observations from the Green Bank Telescope showing ammonia, which is produced on Earth either through industrial processes or by nitrogen-fixing bacteria.
“Even if we confirmed both of those things,” Graves said. [ευρήματα]“It is not evidence that we found these magical microbes and that they live there today,” he said, adding that there were no “ground truths” yet.
“The data is consistent with the observations of the two astrophysicists,” said Professor Nikku Madhusudhan, an astrophysicist at the University of Cambridge, who was not involved in either work.
“When it comes to Venus, those are both open questions,” he said. “If they do confirm phosphine and ammonia, it raises the possibility of a biological origin. The next natural thing is for new people to look at it and provide support or counterarguments. The story will be resolved with more data.”
“All of these are reasons to be optimistic. If they can prove that the signals are there, good for them,” he added.
“However, it should be stressed that the results are only preliminary and more work is needed to find out more about the presence of these two potential biomarkers in the clouds of Venus,” said Dr Robert Massey, Deputy Executive Director of the Royal Astronomical Society in the UK. “However, it is exciting to think that these findings could point to either potential signs of life or some unknown chemical process. It will be interesting to see what further investigations reveal in the coming months and years.”
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