Researchers have often focused on planets similar to Earth in the search for alien life, which are usually full of oxygen and water. However, scientists are open to the possibility that life could exist in conditions very different to ours. This is why, when the James Webb Space Telescope (JWST) launches in 2021, it will look for planets with carbon monoxide in its atmosphere – something which would be extremely poisonous to Earth-based lifeforms.
JWST has detectors on it which will be able to spot the make-up of a planet’s atmosphere from thousands of light-years away.
Edward Schwieterman, the study’s lead author and a NASA Postdoctoral Program fellow in the University of California – Riverside (UCR) Department of Earth Sciences, said: “With the launch of the James Webb Space Telescope two years from now, astronomers will be able to analyse the atmospheres of some rocky exoplanets,
“It would be a shame to overlook an inhabited world because we did not consider all the possibilities.”
The team took early Earth as an example for carbon monoxide breathing life-forms.
In their research, they discovered that three billion years ago, when oceans were teeming with microbial life, the Earth was almost completely void of oxygen, and the sun was much dimmer.
As a result, Earth’s earliest life forms were able to survive on carbon monoxide levels of roughly 100 parts per million – significantly higher than the levels today which registers in parts per billion.
Timothy Lyons, one of the study’s co-authors, a professor of biogeochemistry in UCR’s Department of Earth Science, and director of the UCR Alternative Earths Astrobiology Center, said: “That means we could expect high carbon monoxide abundances in the atmospheres of inhabited but oxygen-poor exoplanets orbiting stars like our own sun.
“This is a perfect example of our team’s mission to use the Earth’s past as a guide in the search for life elsewhere in the universe.”
Dr Schwieterman added: Although other studies have done exoplanet photochemical modelling that includes carbon monoxide, no one had focused on carbon monoxide on Earth-like exoplanets in such a systematic way.
“Now we have a guidebook for determining what levels of carbon monoxide are compatible with a photosynthetic biosphere.”