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Last month, astronomers claimed to have found the strongest evidence ever of alien life on a distant exoplanet named K2-18 b. They believe that exoplanet, which was discovered in 2015, has chemicals in its atmosphere that are only created on Earth by living organisms.
“There may be processes that we don’t know about that are producing these molecules,” Nikku Madhusudhan, Professor of Astrophysics and Exoplanetary Science at the University of Cambridge, said about their discovery. “But I don’t think there is any known process that can explain this without biology.”
Unfortunately, not everyone in the scientific community agreed with those findings. In fact, several scientists thought Madhusudhan and his team jumped the gun a little bit with their claims.
“Life is one of the options, but it’s one among many,” Dr. Nora Hanni, a chemist of the Physics Institute at the University of Berne, told The Guardian. “We would have to strictly rule out all the other options before claiming life.”
Fast forward to this week and Madhusudhan and his colleagues have reanalyzed their data and claim to have even more evidence that these chemicals could only have been produced by alien life.
“Our exploration includes 650 molecules, spanning a wide range of trace gases, including biotic, abiotic, and anthropogenic gases on Earth,” the scientists wrote in their research paper published on the preprint server arXiv. “We investigate possible evidence for any of these gases using three metrics: (a) evidence in the JWST mid-infrared spectrum, (b) evidence in the JWST near-infrared spectrum, and (c) plausible sources of production.
“We find three molecules, including DMS, which appear promising across the datasets considered. The two molecules besides DMS are diethyl sulfide and methyl acrylonitrile, which are more complex than DMS, biogenic on Earth, and have no significant sources known beyond Earth. A few other gases also provide comparable fits to a subset of the data considered but again with limited known plausible sources.”
Madhusudhan doubled down on his team’s original findings that they found evidence of alien life on exoplanet K2-18 b, telling New Scientist, “After our most recent work, I am slightly more confident.”
Again, though, there are naysayers. One of them, Luis Welbanks at Arizona State University, told New Scientist that this new research “is a major change in interpretation within just one month, with no new data, no new retrieval framework, and no newly available [laboratory molecule] data” and that it “strongly suggests the original interpretation was not robust.”
Madhusudhan, of course, disagrees, but his team did at least state in their research paper that their “study highlights the need for further observations to distinguish between possible trace gases in K2-18 b and theoretical work to establish their plausible sources if confirmed on this planet.”