In April, a research team led by Nikku Madhusudhan at the University of Cambridge announced they had detected possible traces of dimethyl sulphide, or DMS, in the atmosphere of K2-18b.
K2-18b is a far-off exoplanet about 124 light-years away. DMS is a compound produced exclusively by living organisms, mostly Marine phytoplankton. That simple A+ B must equal C kind of logic got people’s imaginations running wild.
Well, that excitement can be thoroughly walked back now.
Scientists Are Watching K2-18b for Possible Signs of Life
New Scientist reports that while the planet observed by the James Webb Space Telescope sounded promising, since K2-18b sits in the habitable zone of its star and is about eight times Earth’s mass, making it a perfect candidate for observing the early signs of alien life, we may have killed that dream by observing it a little too closely.
Follow-up observations and independent analyses have failed to confirm the presence of DMS or any other clear biomolecule. According to Luis Welbanks of Arizona State University, the only gases scientists can say with confidence are present are methane and carbon dioxide. The original claim, he says, relied too heavily on weak data and optimistic statistics.
None of this is to say that the idea of life on the planet can be completely written off. There’s still that strange initial spike in the data that scientists need to now reinterpret. Researchers like Jake Taylor at the University of Oxford agree it’s real, even if its cause is unknown.
Figuring out what’s behind it will require more JWST observations, which are already planned for next year. It’s a slow process, however, since K2-18b only passes in front of its star four times a year, meaning its window of visibility is quite narrow.
The alien hype is all but dead, but the whole episode has helped XO planet researchers tighten their standards and help them better understand what they’re looking at when they spot something unusual in the distant stars.
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