When it comes to alien hunting, astronomers have already done a pretty good job of checking out the planets in our own cosmic backyard. Sure, there might be some kind of alien space whale lurking under the ice of Enceladus, but generally speaking we know that there isn’t another Earth-like planet in our neck of the woods. But determining whether a distant planet in another star system supports life is a lot more difficult. Now, a team of researchers has come up with a new and possibly more effective way to detect extraterrestrial life from millions of miles away, and it’s all about gasses.
In a new paper published in Science Advances, researchers led by Joshua Krissansen-Totton of the University of Washington suggest that rather than searching for life itself we should be hunting for specific mixes of atmospheric gasses that couldn’t exist without the presence of life.
By closely studying the various mixes of gasses that exist in Earth atmosphere, and considering how life on other worlds might form even without oxygen, the team argues that by finding planets where different gasses exist in an unbalanced way we’ll be much closer to discovering life.
“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,” Krissansen-Totton explains. “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.”
The idea is that planets without life will have relatively predictable mixes of gasses existing in a sort of stable balance, but if we’re able to detect a world where gasses aren’t in an equilibrium it will be a major red flag that life is present there, even if it’s much different from life as we know it on Earth. Specific chemical imbalances — such as the presence of methane and carbon dioxide but with an absence of carbon monoxide — would be huge signals for alien hunters.