Possible Biosignature Detection On Exoplanet K2-18 b?

Keith’s note: Some interesting news from Cambridge University. Astronomers using the James Webb Space Telescope have detected “a tentative hint of dimethyl sulfide (DMS)“. A biosignature, simply defined, is a substance that is usually produced by life. It can often also have non-life sources. But usually when it is detected in certain circumstances it is a blinking light for something interesting. Follow-up research will be required – by multiple teams. As Carl Sagan is often quoted as saying “Extraordinary claims require extraordinary evidence”. NASA helped fund this research – research that is at the core of Astrobiology. Let’s see if they talk about it. Or not. To be clear: no one has discovered extraterrestrial life. At best they have noticed the hint – of a hint – of something that is worth looking into.

• According to “New Constraints On DMS and DMDS In The Atmosphere Of K2-18 b From JWST MIRI“: “Recent JWST transmission spectroscopy of the candidate hycean world K2-18 b in the near-infrared led to the first detections of carbon-bearing molecules CH₄ and CO₂ in its atmosphere, with a composition consistent with predictions for hycean conditions. The observations also provided a tentative hint of dimethyl sulfide (DMS), a possible biosignature gas, but the inference was of low statistical significance. … The results also highlight the need for additional experimental and theoretical work to determine accurate cross sections of important biosignature gases and identify potential abiotic sources. We discuss the implications of the present findings for the possibility of biological activity on K2-18 b.“
• According to “Strongest Hints Yet Of Biological Activity Outside The Solar System” from Cambridge University: “Using data from the James Webb Space Telescope (JWST), the astronomers, led by the University of Cambridge, have detected the chemical fingerprints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b, which orbits its star in the habitable zone. On Earth, DMS and DMDS are only produced by life, primarily microbial life such as marine phytoplankton. While an unknown chemical process may be the source of these molecules in K2-18b’s atmosphere, the results are the strongest evidence yet that life may exist on a planet outside our solar system.”