Finding Aliens: Atmosphere Data Could Help Identify Faraway Planets Like Earth [VIDEO]
When the James Webb Space Telescope — NASA's next-generation stargazer designed to one-up the Hubble telescope — launches in 2018, it will give astronomers long-coveted capabilities. It can peer further into the depths, allowing us to witness the origins of the universe. And it will pack even more powerful infrared technology to see parts of the cosmos we couldn't before.
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For astrobiologists, those concerned with finding life in space, the telescope's showpiece is its capacity to guage the atmospheric pressure of alien worlds that contain coupled molecules (or "dimers") of oxygen. If the atmospheric pressure is strong enough, it means the air is heavy enough to keep liquid water on the surface of the planet. It would also mean, of course, that there's oxygen in the atmosphere, a hallmark of photosynthesis. "Dimer features could be the most readily detectable biosignatures for Earth-like atmospheres," wrote a team of Seattle scientists who detailed the method for interpreting the data in the journal Astrobiology.
Astronomers have been discovering new planets at a steady clip over the last decade or so. Recently, the pace of discovery has exploded. Of the 1,700 confirmed exoplanets, NASA discovered 715 of them since the beginning of this year alone by using more efficient confirmation techniques. They do this using data collected by a telescope called Kepler, which, until 2011, scanned the universe for two years looking for subtle stellar eclipses — moments when distant planets pass between their star and the telescope.
Scientists call this moment when the planet obscures the star a transit. And this transit is the same basis for the atmospheric measurements that the James Webb telescope will observe. Certain molecules in the atmosphere of exoplanets absorb light, as Science puts it, "like a color filter on a camera lens." By testing what kind of light and how much is absorbed, scientists can determine the concentration of oxygen and the atmospheric pressure.
If they can identify oxygen floating around an Earth-sized planet, potentially laden with liquid water, then they've discovered the Holy Grail of astrobiology. "The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis," the authors wrote. That's because, according to Science, no one knows of another way to oxygenate a planet except through photosynthesis — the conversion of sunlight into energy for organic matter.
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