- In their search for life on other planets, scientists say they want to start using a new sense: smell.
- They’re hoping that by sniffing out and tracking down chemicals like methane and carbon dioxide via telescope, they’ll be able to find more places that could be good breeding grounds for microbes, even if there’s no oxygen present.
Is anybody out there?
It’s a question astronomers wonder as they probe distant corners of the universe, tirelessly searching for signs of life outside of Earth.
A new study from scientists at the University of Washington argues that telescopes could perform a new kind of “sniff test” for life, looking for gases like methane and carbon dioxide that might bring new clues about where other organisms could exist.
The idea posited in the study, published in the journal Science Advances Wednesday, is that telescopes could track down “atmospheric chemical disequilibrium,” a cocktail of chemicals that wouldn’t normally be compatible with one another over long periods of time, but might be able to co-exist if they were also in the presence of life.
Some telescopes, including NASA’s James Webb Space Telescope (set to launch in 2019), have a capability called “spectroscopy” which measures both radio waves and light. That’s helpful because hot gases emit distinct wavelengths of light, so by peering through a telescope, scientists can pinpoint the “smell” of different chemicals in space, and know precisely which elements are present on other worlds.
The scientists say it’s not enough to look for oxygen, which would be a tell-tale sign that life existed on another planet. After all, other beings or organisms might not even need oxygen. If they exist, they probably aren’t just like us.
“We need to look for fairly abundant methane and carbon dioxide on a world that has liquid water at its surface, and find an absence of carbon monoxide,” study author and astrobiologist David Catling said in a release. He’s pretty sure that a recipe of methane, carbon dioxide and surface water would be a compelling signal that there is life nearby.
The researchers hope that NASA will take note of their new sniffing strategy as the agency prepares to launch the James Webb telescope next year. The telescope will check out exoplanets like the TRAPPIST-1 system, a neighborhood of seven rocky globes outside our solar system that scientists think could be habitable. If the telescope can take a whiff of the newly-discovered planets, it could get us closer to answering our questions about life in the universe.
But not everyone is certain that the technique will work smoothly. Astronomer and MIT professor Sara Seager has said using spectroscopy to examine into distant rocky planets will likely lead to false positive reports of chemicals and gases.
“We may not be able to point to a planet with certainty and say, ‘That planet has signs of life,'” she wrote in a 2014 paper about spectroscopic life detection. She said successfully sniffing for alien life is something that’s going to require next-generation telescope technology that doesn’t yet exist.
Still, she said “with enough rocky worlds with biosignature gases, we will inspire confidence that life not only exists in the solar neighborhood but is common in our Galaxy.”