No Statistically Significant Biosignatures in K2-18b’s Atmosphere: JWST/MIRI Analysis Points to Instrument Systematics

To the point

Stevenson, Lustig-Yaeger, May, Kopparapu, Fauchez, Haqq-Misra, Limbach, Schwieterman, Sotzen, and Tsai show that JWST/MIRI observations of K2-18b do not provide robust biosignatures once instrument systematics are accounted for, that the tentative DMS/DMDS signal is highly binning-dependent and largely unreliable, and that methane and CO2 detections are likely due to red noise, with recommendations to minimize instrument effects in future reductions.