Finding alien life won’t be as dramatic as a flying saucer landing on the White House lawn – it’ll be NASA scientists holding a press conference to excitedly show off a chart that’s incomprehensible to most people. Now, we’re a step closer to that boring but groundbreaking day.
Astronomers from the University of California, Riverside (UCR) have identified a new potential signature to look for in the atmospheres of exoplanets, which could indicate life is present. It’s a group of gases called methyl halides, which are made up of a carbon atom and three hydrogen atoms bound to a halogen atom.
Here on Earth, these gases are almost entirely emitted by lifeforms like bacteria, algae, fungi and a few plant species. They make up a pretty small proportion of our atmosphere, but the researchers’ modeling suggested that they should build up significantly around a particular type of exoplanet.
Hycean worlds are a class of mini-Neptunes that are believed to host global oceans of liquid water on their surfaces, beneath a hot, high-pressure atmosphere rich in hydrogen. That special mix of Hycean air would lend itself to an accumulation of methyl halides, the UCR team says, if microbes living in those oceans are belching them out.
Better yet, when these planets are viewed in infrared, those methyl halides would provide a strong, clear signal as they absorb certain wavelengths of light. And that’s just the kind of light that the James Webb Space Telescope is using to scan the skies.
“One of the great benefits of looking for methyl halides is you could potentially find them in as few as 13 hours with James Webb,” said Michaela Leung, first author of the study. “That is similar or lower, by a lot, to how much telescope time you’d need to find gases like oxygen or methane. Less time with the telescope means it’s less expensive.”
These signals should be visible, the team calculates, even if the methyl halide concentrations are as low as 10 parts per million (ppm). James Webb and future infrared telescopes could soon be finding these signatures regularly.
“If we start finding methyl halides on multiple planets, it would suggest that microbial life is common across the universe,” said Leung. “That would reshape our understanding of life’s distribution and the processes that lead to the origins of life.”
If we’re lucky, we could get that Nobel Prize-winning PowerPoint presentation sooner than we hoped.
The research was published in Astrophysical Journal Letters.
Source: UCR
