Is the presence of oxygen in the atmosphere of an alien world the only sure-fire sign that life is present? Not necessarily: Scientists say the chemical signature of biological activity is likely to be more subtle, involving a mix of gases that might seem out of whack.
In a paper published today in Science Advances, researchers say future observatories such as NASA’s James Webb Space Telescope should look for the signature of atmospheric gases that would be in disequilibrium if it weren’t for biological processes.
The study’s lead author, Joshua Krissansen-Totton of the University of Washington, says looking for oxygen alone shouldn’t be the sole strategy in the search for life on extrasolar planets.
“This idea of looking for atmospheric oxygen as a biosignature has been around for a long time. And it’s a good strategy — it’s very hard to make much oxygen without life,” he said in a news release. “But we don’t want to put all our eggs in one basket. Even if life is common in the cosmos, we have no idea if it will be life that makes oxygen. The biochemistry of oxygen production is very complex and could be quite rare.”
