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JWST spots the same unknown organic on Pluto and Titan
James Webb observations found an identical unexplained infrared signature on Pluto and Titan, pointing to an unknown organic compound.
Image: iXBT
Pluto and Titan are about as different as worlds in the outer Solar System get, yet James Webb Space Telescope observations suggest they may share the same unexplained surface chemistry. Scientists say both bodies show an identical infrared signature at the same wavelength, hinting at an unknown compound — or a related family of compounds — on both worlds.
Titan, Saturn’s haze-covered moon, is geologically active and has a thick atmosphere, seas of liquid methane, and vast dunes made from organic particles that fall from the sky. Pluto, by contrast, is a frozen dwarf planet with a thin atmosphere above an icy surface. Despite those differences, the new study says both show the same light-absorption feature.
“It’s quite mysterious. We cannot say what it is.”
Researchers identified the signal using spectroscopy, which matches compounds to the wavelengths of light they absorb. According to the study, this newly detected feature does not match any standard spectrum currently in library catalogs. The team also says it is unlikely to be an instrument glitch: the same absorption feature was seen by two different JWST instruments, NIRSpec and MIRI.
Bézard said he turned to colleague Emmanuel Lellouch of the Paris Observatory, who led the JWST program that observed Pluto in May 2023, to check whether Pluto showed the same feature. It did.
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The researchers say there is no evidence the molecule is a biosignature. Bézard instead said it likely reflects prebiotic chemistry operating in Titan’s oxygen-free environment for more than 4 billion years. One leading idea is that the signal could come from allenes, a family of hydrocarbons that the study says are among the only known organic compounds with strong absorption bands in the same 5-micron infrared range.
Frontier Editor
Dan is our resident futurist, covering electric mobility, space exploration, and the smart home. He's interested in atoms just as much as bits. Whether it's a new battery chemistry, a reusable rocket, or a protocol that finally makes IoT devices talk to each other, Dan breaks down the engineering that pushes humanity forward.
via iXBT
