Scientists believe that the atmosphere of the exoplanet K2-18b is mainly made up of hydrogen, and now a new study by the Massachusetts Institute of Technology has found that E. coli and yeast can survive in an atmosphere of 100% hydrogen, so K2-18b may be better suited to life than previously thought. Now, microbes on Earth have also been found to live in the hottest and coldest places on Earth, soaring in the upper atmosphere and settling on rocks half a mile below the bottom of the sea. Experiments have even shown that some microbes can survive in harsh conditions in space.
We humans may not live comfortably in the cold deserts of Mars or in Titan’s biogas lakes, but that may be a haven for some microbes. Exoplanets, whose atmosphere is mainly made up of hydrogen, have traditionally been considered uninhabitable, and now a team at the Massachusetts Institute of Technology has rejected that view.
The researchers exposed E. coli and yeast cultures to 100% hydrogen, and to their surprise, the microbes performed well. Their reproduction rate did slow down, but it did not prevent them from breeding. For E. coli, the reproduction rate has decreased by about half, while the rate of yeast reproduction has decreased by 2.5 orders of magnitude. According to the team, this is most likely due to a lack of oxygen.
This discovery means that we may need to revise the standards for what is a livable planet. Hydrogen-dominated super-Earths, for example, may be suitable for microbial reproduction, and they may be more likely to be found than other types of planets because the hydrogen atmosphere will expand farther than other types of planets.
The team also said that we may have been able to find out if any of these planets were home to extraterrestrial life. E. coli and other bacteria are known to produce gases such as ammonia, dimethyl sulphides, nitrous oxide and methane. The detection of these gases on hydrogen-based planets may indicate the existence of life there.