Earth's cousins: upcoming missions to look for 'biosignatures' in exoplanet atmospheres

Earth's cousins: upcoming missions to look for 'biosignatures' in exoplanet atmospheres: Scientists have discovered thousands of exoplanets, including dozens of terrestrial—or rocky—worlds in the habitable zones around their parent stars. A promising approach to search for signs of life on these worlds is to probe exoplanet atmospheres for 'biosignatures'—quirks in chemical composition that are telltale signs of life.