BackIs there life on Venus? Scientists say maybe
Using telescopes, scientists measure signs of phosphine gas in the atmosphere of inhospitable planet—a possible sign of biological life
PremiumAn international group of scientists reported the detection of small quantities of a gas in the atmosphere of Venus they believe could be a sign of biological life on the often-overlooked planet. The findings need to be confirmed with additional measurements, the researchers and other experts said.
The gas, known as phosphine, is a rare, hard-to-detect molecule typically produced in highly inhospitable environments that lack oxygen, like the violent depths of Jupiter and Saturn.
“We found a unique signal in Venus for which the most likely explanation is phosphine, and the most likely explanation for phosphine seems to be life," said Clara Sousa-Silva, a Massachusetts Institute of Technology quantum astrochemist and one of the authors of the study. “It does seem kind of extraordinary. Even I’m skeptical."
The team pointed to two possible explanations for the findings—“some crazy, unknown chemistry, or life on Venus," said Sara Saeger, an MIT planetary scientist who worked on the study. “They’re equally probable."
She and others pointed out that on Earth, phosphine can be found in sewage facilities or the intestines of living organisms, though at extremely low levels. At higher concentrations, it can be toxic.
The results, published Monday in the journal Nature Astronomy, could turn a new spotlight onto Earth’s second-closest neighbor, whose surface was once much cooler and may have had oceans.
Despite its relative proximity to our home planet, Venus has been long overlooked in planetary research, some scientists say. Some hope the new study will add Venus to the list of potentially habitable worlds and turn the tides for the bright planet.
“Venus was beloved for a long time," said Dr. Sousa-Silva, and attracted research, but “the probes that we sent melted quite dramatically and barely survived long enough to send back any signals, so it was really hard to keep doing that to ourselves."
The surface of Venus is an “abominable place," she added, but “the clouds themselves could be habitable." She and her team detected phosphine in the clouds, using telescopes on Earth aimed at Venus.
The instruments measured radiation patterns. Molecules naturally absorb radiation at certain known wavelengths. By assessing blips, or dips, in those signals, the researchers can infer that certain compounds, like phosphine, are present.
For years, much more attention and resources have been trained on Mars and moons like Jupiter’s Europa and Saturn’s Enceladus—icy ocean worlds that scientists suspect may also host life.
“It’s not the determination of alien life…[but] maybe this is actually a world we should be more credibly thinking about habitability," said Paul Byrne, a North Carolina State University planetary scientist who wasn’t involved in the research. “It’s a massive deal, hands down."
Some scientists cautioned against drawing conclusions too early.
“I think the data are robust.… The experiment was done meticulously," said Darby Dyar, chair of astronomy at Mount Holyoke College in Massachusetts, who wasn’t involved in the research. “The interpretation is a little more difficult," she said. “The problem is that we haven’t thought too much about whether phosphine can be created abiotically" on Venus, in part because we know so little about the planet and its chemistry.
Even on Earth, the process by which phosphine is synthesized isn’t completely understood, scientists said.
The study detected minute amounts—5 to 20 parts per billion—in the Venusian atmosphere. On Earth, quantities are measured in parts per trillion or quadrillion, according to Dr. Sousa-Silva.
The researchers want to confirm with additional measurements that the molecule they detected is in fact phosphine. Every molecule vibrates and rotates with unique patterns, and these molecular dances act like signatures. The team found one such signature in this round of experiments based on the way phosphine rotates. Next up would be to look at its vibrations with infrared sensors to confirm the initial observations.
“That extra information really helps to pin things down," said Steven Shipman, associate professor of physical chemistry at the New College of Florida in Sarasota, in an email. “While it’s possible it could be another molecule, if so, it’s not something obvious.… So it probably really is phosphine."
Until orbiters can sample the atmosphere for more direct signs of life, scientists say, the debate over whether Venus is habitable and inhabited will continue.
Write to Daniela Hernandez at daniela.hernandez@wsj.com
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