Do aliens live on toxic, smelly worlds?
Researchers at the Massachusetts Institute of Technology, led by astrobiologist Clara Sousa-Silva, set out to answer that question. They recently published a study detailing their work, revealing a potential new method for finding alien life: By detecting planets with atmospheres containing phosphine.
In their study, titled “Phosphine as a Biosignature Gas in Exoplanet Atmospheres,” the researchers determined that the presence of phosphine, one of the nastiest gasses here on Earth, could be a major indicator that life exists on a planet.
That’s because, according to their research, anaerobic organisms — bacteria and microbes that don’t require oxygen — are the only things known to produce phosphine naturally on rocky planets like ours. And so, if you can detect phosphine on a rocky exoplanet, there’s a good chance life is present there, as well.
(While phosphine can also be found in gas giants like Jupiter and Saturn, this is due to their immense pressures and tumultuous environments.)
On Earth, phosphine is a flammable and explosive gas typically found in places where oxygen is not, such as swamps, marshlands, and big old piles of penguin dung. However, according to Sousa-Silva (via MIT News), lifeforms that don’t like oxygen take to it very well:
“It’s a really toxic molecule for anything that likes oxygen. But for life that doesn’t like oxygen, it seems to be a very useful molecule.”
What’s more, if phosphine were produced on an exoplanet in amounts similar to that of methane here on Earth, it would generate enough of a signal that we’d be able to detect it. However, we’d need a telescope powerful enough.
Lucky for us, the James Webb Space Telescope fits the bill, and is scheduled to launch on March 30, 2021. In that case, we may be able to detect such phosphine-rich planets up to 16 light years away.
Other molecules could also prove to be potential biosignatures, according to Sousa-Silva:
“Here on Earth, oxygen is a really impressive sign of life. But other things besides life make oxygen too. It’s important to consider stranger molecules that might not be made as often, but if you do find them on another planet, there’s only one explanation.”
Gas: In Space!
Speaking of Space Gas, another recent study discovered a new way to find exoplanets themselves — by looking for stars “shrouded in gas.”
This technique, according to a team of astronomers at the Open University in England, involves looking for stars that appear to be enveloped by gas clouds. In truth, however, these “gas clouds” are actually made up of material from planets that are so close to their host stars that they’ve begun to vaporize from the heat.
Astronomers have found six such exoplanets, three of which are super-Earths, orbiting a total of three stars.