JWST is Powerful Enough to See a Variety of Biosignatures in Exoplanets - by BrianKoberlein
While the idea is straightforward, putting it into practice is difficult. For one, starlight isn’t just a steady stream of light. There are flares, starspots, and other turbulence that causes noise in the signal. Even just detecting planetary brightness dips is difficult because of this. And while a planet will block less than a percent of the light, the amount of starlight passing through an exoplanet’s atmosphere is truly minuscule.
The team simulated atmospheric conditions for five broad types of Earth-like worlds: an ocean world, a volcanically active world, a rocky world during the high bombardment period, a super-Earth, and a world like Earth when life arose. They assumed all these worlds had a surface pressure of less than 5 Earth atmospheres, and calculated the absorption spectra for several organically produced molecules such as methane, ammonia, and carbon monoxide.
They found that with a reasonably thick atmosphere, the JWST, specifically its NIRSpec G395M/H instrument, could confirm the presence of these molecules within 10 transits of the planet. It would be easiest to do with super-Earths and other worlds with a thick atmosphere, but it is still possible for potentially habitable worlds.
Given the number of transits needed, our best shot at detecting biosignatures with JWST would be the close-orbiting worlds of red dwarf stars, such as the Trappist-1 system, which has several potentially habitable Earth-sized planets. Given the overlap between biological and non-biological origins, JWST observations might not be enough to confirm the existence of life, but this study shows that we are very close to that ability.
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