We human beings are quite comfortable here on Earth, which has an atmosphere of 78% nitrogen, 21% oxygen, 0.9% argon and 0.03% carbon dioxide, with trace elements of other gases.

But it might be too narrow-minded to think that other alien life forms would thrive in such an atmosphere. Perhaps, they use a different chemistry to ours.

According to a new study, published in Nature Astronomy, scientists argue that the best chance of finding evidence of life on distant worlds is to expand the focus to planets that feature hydrogen atmospheres.

This particular study examined how E. coli bacteria and yeast would react to a 100% hydrogen atmosphere. The scientists saw that they both reproduced normally, but it wasn’t as rapid as in highly oxygenated air. The slower reproduction rates were likely due to the lack of oxygen, the researchers said.

As witnessed in this study, microorganisms can, in fact, survive and reproduce in such an environment. This data can now help drive forward further research into exoplanets that have hydrogen-rich atmospheres and the possibility of life on them.
Rocky exoplanets that are much larger than Earth, perhaps between two and 10 times the mass of our planet, can keep a high amount of hydrogen in their atmospheres. These atmospheres would likely need to be larger and more extended because hydrogen is the lightest of all molecules and can escape into space relatively easily.

According to scientists, the hydrogen could either have been captured directly from the gas cloud where the planet formed or have been released by a chemical reaction between iron and water.

Earth, which began without any oxygen 4.5 billion years ago, is unlikely ever to have had more than 1% hydrogen in its atmosphere.

Another interesting case within our solar system is Saturn’s moon Titan, which is bigger than the planet Mercury. It features a dense cloak of hydrocarbon smog suspended in a nitrogen-rich atmosphere and rivers and lakes of liquid methane. It has been speculated that life could, in fact, exist in liquid methane, just as organisms on Earth live in water.

In strengthening their search for alien life, astronomers and researchers are placing their bets on the James Webb Space Telescope, which is slated to launch next March, and the forthcoming Extremely Large Telescope being built in Chile’s Atacama Desert.

These two high-tech telescopes will help garner “spectral fingerprints” on distant exoplanets, such as ozone, methane and water. With increased knowledge about these atmospheres, the scientists will have a better sense if a particular planet is potentially habitable.

Ethen Kim Lieser is a Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. He currently resides in Minneapolis.