According to a new study, evidence of alien life in the atmospheres of potentially habitable exoplanets could be hidden from prying telescopic eyes by unusual air flow patterns. The research could have significant implications regarding how and where astronomers search for extraterrestrial life on nearby worlds.
Even taking into account the most ambitious of ideas, humankind is unlikely to make the big leap to a neighboring exoplanet any time soon – let's face it, NASA has its hands full getting to Mars at the moment.
So how do astronomers search for life while confined to this Earthly prison? The answer lies in the atmospheres of distant worlds. Scientists know that biological life on Earth has dramatically changed our planet's atmosphere, contributing to the creation of the ozone layer, and adding numerous other biological markers to the protective shell.
Astronomers can task powerful observatories, such as the future James Webb Space Telescope, to look for these biological markers in the atmospheres of promising exoplanets. One of the prime targets for observation are nearby Earth-size worlds such as TRAPPIST-1d, and the closest known exoplanet to Earth, Proxima b, which orbits its star a mere 4.25 light-years away.
Unfortunately, a new study carried out by an international team of astronomers may have identified yet another obstacle to be overcome in the search for E.T.
The scientists ran computer simulations modelling the atmospheric air flow of potentially habitable exoplanets such as Proxima b and TRAPPIST-1d. These exoplanets orbit their parent star in less than 25 Earth days. A side effect of this is that they are tidally locked, meaning that one face of the planet is always facing its star, bathed in perpetual sunlight, while the other experiences a permanent night.
According to the simulations, tidally locked exoplanets could be host to powerful air flows that carry atmospheric elements such as ozone and other potential biological markers away from polar regions, and trap them around the equator, where they are more difficult to detect by our telescopes.
This atmospheric quirk could also damage an exoplanet's chances of sustaining life. Earth's ozone layer protects terrestrial life from the harmful ultraviolet radiation emitted from our Sun.
If the new computer simulations are correct, the trapping of ozone in the equatorial region of tidally locked exoplanets could be a bad indicator for the habitability of these worlds.
That being said, the team behind the new research has stressed that even if the atmospheres of these exoplanets are as dramatically different from Earth's as the simulation suggests, they could still play host to life around their equatorial regions.
For those who were caught up in the initial excitement surrounding the discovery of the nearby Earth-sized exoplanets, the newly-published study represents the latest in a series of significant doubts as to whether these worlds can actually play host to life.
Some of the studies examined whether the exoplanets could withstand the violent nature of the red dwarf stars that they orbit, which are prone to releasing punishing bursts of ultraviolet radiation. This radiation has the potential to severely deplete an orbiting exoplanet's atmosphere, and with it, its chances of hosting life.
A paper detailing the research has been published in the Monthly Notices of the Royal Astronomical Society.
Source: Royal Astronomical Society
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