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NASA's James Webb Telescope Could Detect Alien Life in Just 20 Hours

No pressure.

NASA's James Webb Telescope Could Detect Alien Life in Just 20 Hours
An artist's impression of an alien world. dottedhippo / iStock

We're just weeks away from the next generation of astronomy.

When the James Webb Space Telescope launches in December, it will signal the beginning of a new day for the study of the universe, and officials at NASA and elsewhere think it could discover signs of atmospheres capable of supporting life on alien worlds beyond our solar system. But what will the process of evaluating these planets look like, and how long will it take?

It turns out, some planets could reveal signs of life with only five to 10 co-added transits — roughly 20 hours, according to a recent study shared on a preprint server.

Of course, it might not happen in 20 consecutive hours, but this is lightning fast.

The James Webb telescope will transform exoplanet studies

There are several methods of identifying and analyzing the properties of alien worlds beyond our solar system. It's pretty rare for a telescope to view distant worlds the way we see planets in our solar system, simply from the reflection of our sun's light. This is why the transit method has proven the most robust so far. The transit method is a means of detecting and studying the properties of a planet via the "dip" in the brightness of its host star as the planet passes between it and us, like a really tiny solar eclipse. But when the James Webb Space Telescope (JWST) goes live, it will transform exoplanet studies, possibly offering the first chance scientists have ever had to search for biosignatures in the atmospheres of alien worlds via transmission spectroscopy.

300 million planets might support life in our galaxy

Looking to verify this claim, the researchers set out to explore how this method would play out for the JWST when it looks for two compounds that point to the presence of life: CH4 and C02 (methane and carbon dioxide). Specifically, on a promising candidate called TRAPPIST-1e, which scientists suspect has atmospheric conditions similar to the Archean Earth (2.5 to 4 billion years ago). While no assumptions were made in the study about the composition of the cloud/haze layer of this alien world, the researchers found that the JWST might only need 5 to 10 co-added transits, measured via the telescope's Near-Infrared Spectrograph (NIRSpec) prism, to confirm strong detections. But this will only happen if the atmosphere is clear, and the pressures of its cloud/haze layer are between 100 and 600 millibars (0.1 to 0.6 of Earth's atmospheric pressure at sea level).

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On the other hand, if TRAPPIST-1e has a cloud/haze-layer pressure of 10 millibars (0.01 atmospheres), it could take up to 50 transits of TRAPPIST-1e in front of its host star, which could take JWST more than 200 hours of observation. Of course, it might be years before we know for sure that a planet orbiting a distant star has an atmosphere conducive to life as we know it. But with so many potential candidates — possibly millions in our galaxy, depending on conditions surrounding red dwarf stars — awaiting closer inspection with the James Webb Space Telescope, it's officially time to indulge yourself with the hope that the search for life beyond Earth is reaching that critical threshold, where the big question mark about our aloneness in the universe turns into an unmistakeable exclamation.

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