Scientists have discovered a new clue in the search for extra-terrestrial life, with Nasa’s James Webb telescope playing a pivotal role.
Researchers at the University of Birmingham and the Massachusetts Institute of Technology (MIT) believe that looking at the levels of carbon dioxide in a planet’s atmosphere could provide answers as to whether other parts of the universe are inhabited.
They propose that if a planet has less carbon dioxide in its atmosphere compared to its neighbours in the same system, it could mean that there is liquid water, or even possibly life, on the planet’s surface.
The theory is due to the idea that a reduced level of the gas means that oceans and gas are sucking up carbon dioxide.
The James Webb Space Telescope (JWST) was launched in 2021FlickrNasa’s James Webb telescope is believed to be the best contender to search for the low levels, as it has been used previously to detect atmospheric conditions of exoplanets.
The presence, or lack thereof, of carbon dioxide is the only sign of life that is detectable with current technology, the team of scientists said.
“The Holy Grail in exoplanet science is to look for habitable worlds, and the presence of life, but all the features that have been talked about so far have been beyond the reach of the newest observatories,” says Julien de Wit, assistant professor of planetary sciences at MIT.
“Now we have a way to find out if there’s liquid water on another planet. And it’s something we can get to in the next few years.”
Over 5,200 worlds beyond our own system have been detected by astronomers so far.
Using current telescopes, scientists can measure a planet’s distance to its star and how long it takes for it to complete an orbit.
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Whilst this information gives researchers information about whether a planet is in a possible habitable zone, it does not provide details about whether liquid water exists on its surface.
Within our own solar system, scientists use “glints” – flashes of sunlight that reflect off liquid surfaces – to detect the presence of liquid water.
This method helped identify lakes on Saturn’s largest moon, Titan.
Yet this technology does not stretch to far-off plants outside of our solar system.
The scientists, whose findings appear in Nature Astronomy, came up with the theory after looking at planets in our own system.
They compared Venus, Earth and Mars, who all have similar rocky, temperate regions.
However, Earth differs from its next-door neighbours as it is the only one with liquid water and low levels of carbon dioxide in its atmosphere.
Earth is the only planet in our solar system with liquid water and low levels of carbon dioxide in its atmosphere
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Researcher Martin Turbet said: “We assume that these planets were created in a similar fashion, and if we see one planet with much less carbon now, it must have gone somewhere.
“The only process that could remove that much carbon from an atmosphere is a strong water cycle involving oceans of liquid water.”
The next step would be to work out which planets have atmospheres by looking for carbon dioxide. De Weit explained: “Carbon dioxide is a very strong absorber in the infrared and can be easily detected in the atmospheres of exoplanets.
“A signal of carbon dioxide can then reveal the presence of exoplanet atmospheres.” However, the scientists pointed out that the presence of the gas does not mean that the world in inhabited.
Ozone was also identified as a key feature for potential life.
“If we see ozone, chances are pretty high that it's connected to carbon dioxide being consumed by life,” Triaud said.