A new analysis of exoplanet K2-18 b using the James Webb space telescope has cast doubt on the initial claim that a biosignature, specifically dimethyl disulphide (DMS), was detected on the planet. The research team behind the original finding now rejects it, suggesting that there may be significantly less DMS than assumed, and its presence could be explained by abiotic processes.
The exoplanet’s water content is confirmed to be substantial, with a possible large ocean or deep shell under its thin atmosphere. However, the traces of DMS found are marginal and below the threshold of 3 sigma initially reported. Researchers have created models showing that DMS can be produced without living organisms, rendering it an unlikely biosignature.
This latest development adds to the growing skepticism surrounding K2-18 b as a potential discovery of extraterrestrial life. The planet’s signal was previously met with criticism, and this new analysis only further erodes confidence in the initial claim. Even if DMS were found in quantities difficult to explain by non-biological means, it would not be conclusive proof of life beyond Earth.
Source: https://www.heise.de/en/news/Exoplanet-K2-18-b-No-trace-of-extraterrestrial-life-on-a-water-world-after-all-10499522.html