Life on Venus? The new discovery deepens the controversy over possible signs of life in the planet’s atmosphere

Recent observations of Venus have yielded new evidence of a compound in its atmosphere that could indicate the presence of life, according to findings that potentially add weight to controversial past discoveries.

Phosphine, a toxic gas that astrobiologists say could be linked to the presence of life on rocky planets, was originally detected in the atmosphere of Venus in a surprise discovery four years ago. Now, new observations potentially reinforce these past findings, suggesting the presence of biological signatures that, if confirmed, could mean that life forms are able to thrive in the planet’s harsh environment.

Controversial discovery on Venus

The initial detection of phosphine in the oxidized atmosphere of Venus was reported in September 2020, when a team of scientists led by Jane Greaves of Cardiff University said they had found evidence of the toxic molecule. The discovery initially led to debate about the possibility of life on Venus, as phosphine is normally associated with organisms that thrive in low-oxygen environments.

The team’s announcement generated considerable media attention and also led to controversy, culminating in rebukes from some in the scientific community. Probably the harshest criticism came from the International Astronomical Union’s (IAU) F3 Commission on Astrobiology organizing committee, which even questioned the ethics of Greaves and her team over the way the discovery was revealed.

“It is the ethical duty of every scientist to communicate with the media and the public with great scientific rigor and to be careful not to exaggerate any interpretation that is irretrievably captured by the press,” the commission wrote in an official statement released at the time.

The commission added that it “would like to remind relevant researchers that we need to understand how the press and media behave before we engage with them”.

Initial follow-up attempts to re-detect the compound were unsuccessful. But last year, Greaves and her team managed to detect phosphine in the deeper parts of the planet’s atmosphere during observations made by the James Clark Maxwell Telescope (JCMT) at the Mauna Kea Observatory in Hawaii. Additional detections by NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) also indicated the presence of phosphine, which may have originated either in or beneath the clouds of Venus.

Interestingly, a separate research effort led by Rakesh Mogul with California State Polytechnic University reanalyzed data obtained by NASA’s Pioneer Venus Large Probe in 1978 and revealed additional support for the presence of phosphine in the planet’s atmosphere that seemed to match earlier findings.

“To date, our analyzes remain unchallenged in the literature,” Mogul said of his team’s findings, which he characterized as “in stark contrast to the telescopic observations” made by Greaves and her colleagues, which Mogul said “remain controversial.”

The new findings still warrant caution

With the help of a new receiver installed on the James Clerk Maxwell Telescope, Greaves and her colleagues now say they have collected up to 140 times more data than previous observations, which include additional detections of phosphine. The new findings were revealed in two presentations by Greaves and David Clements, an Imperial College London researcher who was involved in the discovery, on July 17 during a meeting of the Royal Astronomical Society.

Of even greater potential interest in the search for possible life forms on Venus, however, is the evidence that ammonia is present in its atmosphere, which Clements called “more significant than the discovery of phosphine.” A 2021 study by Mogul and colleagues also found that ammonia could potentially exist in Venus’ atmosphere.

Despite the potential significance of the discovery, during Greaves’ lecture at the Society’s meeting earlier this month, the image in her presentation emphasized that there are “many significant unknowns about Venus’ surface and atmosphere,” adding that “even the discovery of the ‘gold standard’ from two bio-associated molecules are not proof that life exists!

Similarly, Clements told CNN that it would be premature to speculate that these gases point to the existence of life on Venus, although he admitted that the presence of ammonia, along with phosphine, certainly strengthens the possibility.

Promising preliminary findings

Greaves cautioned against jumping to conclusions, explaining during her presentation this month that there is at least a possibility that any organisms present on Venus could produce ammonia that would help reduce the acidity of the environment, making it more habitable. If that were the case, Greaves and her colleagues speculate that the gas could potentially have risen into the atmosphere, allowing it to be detected.

“Ammonia was detected in the upper clouds, where temperatures are -15°C or less and probably too cold for life to exist,” said a post on the Royal Astronomical Society’s official X account summarizing Greave’s presentation.

“Researchers want to find out if the molecule is also present deeper in the clouds of Venus, where it is much warmer,” he added.

Additional confirmation will be required in the future and can be obtained in one of several ways. One possibility is data that could be collected by NASA’s Deep Atmosphere Venus Investigation of Noble gasses, Chemistry and Imaging (DAVINCI) mission, which will send a probe into the harsh environment of Venus in 2029 to measure its atmosphere.

Another potential chance to measure the planet’s atmosphere could be provided by the European Space Agency’s Jupiter Icy Moons Explorer, which will fly close to Venus next year and is equipped with instruments that could potentially provide useful data that can complement the findings of Greaves and her colleagues.

Until these data are obtained, the new findings remain inconclusive, although promising.

“Again, it’s important to emphasize that these are preliminary findings,” the company said in its post on X.

Micah Hanks is the editor-in-chief and co-founder of The Debrief. He can be reached by e-mail at the address micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.