NASA's most eye-catching hints of alien life on Mars and a distant exoplanet left headlines breathless in 2025, but a major new survey of hundreds of astrobiologists suggests most experts do not yet believe extraterrestrial life has probably been found.
The excitement began with two heavily publicised announcements. In April 2025, researchers studying the exoplanet K2-18b reported possible traces of dimethyl sulphide and dimethyl disulphide in its atmosphere, molecules associated with biological activity on Earth. Later, in September, NASA said a Martian rock dubbed 'Cheyava Falls' appeared to preserve a potential biosignature in the form of 'leopard spots' mineral rings that, on Earth, are often linked to microbial life.
