Planets with hydrogen-rich atmospheres could harbor life
Microbes can live and grow in an atmosphere of pure hydrogen, lab experiments show. The finding could widen the range of environments where astronomers seek signs of alien life. “We’re trying to expand people’s view of what should be considered a habitable planet,” says exoplanet astronomer Sara Seager of MIT (SN: 10/4/19). “It seems to increase our chances that we may find life elsewhere.” Seager and her colleagues placed yeast and E. coli — both considered stand-ins for other single-celled organisms — in small bottles with some nutrient broth. The researchers displaced the air in six bottles and replaced it with pure hydrogen gas, pure helium gas or a mixture of 80 percent nitrogen and 20 percent carbon dioxide. A final set of bottles was left with Earth air. Every few hours, the researchers removed some of the microbes with a hypodermic needle to count how many were alive. The microbes had replicated in every atmosphere tested, the team reports May 4 in Nature Astronomy,...