How NASA's hugest telescope ever could seek out life on a nearby exoplanet

Contributed by
Aug 13, 2017

Astronomers have had a telescopic eye on exoplanet Proxima Centauri B since last year, but they may soon get an unprecedented closeup of it with NASA’s upcoming monster scope.

Proxima B is a rocky Earth-size planet that orbits the star Proxima Centauri. What has really ignited curiosity about it is that it resides in the habitable zone of its star (don’t say “Aliens!” yet), which could mean liquid water and even life if atmospheric and environmental conditions align. Because Proxima B is only 4.5 light-years away, it’s actually not impossible to send a space telescope over there. The one NASA has in mind is huge. So huge that Hubble better watch out.

NASA’s James Webb Space Telescope (JWST), aka its “premier observatory of the next decade,” boasts a mirror thrice the size of Hubble’s and has earned bragging rights for being the most enormous and powerful observatory designed to float around in space (goes to show how "micro" microgravity really is). It will orbit the sun to examine planetary heat emissions, which eliminates the possibility of interference from Earth’s atmosphere. The space agency has high expectations for it to beam back everything from hi-res images of distant planets to insights about how stars, planets, and galaxies emerged and evolved billions and billions of years ago.

Until now, nothing has been able to zoom in close enough to Promixa B to tell if it even has an atmosphere, and if so, whether its chemical composition could support life as we know it. This won’t exactly be easy even with such advanced equipment. Proxima Centauri is much brighter than its satellite, whose faintness could prove a problem when probing its atmosphere (if it has one). Astronomers propose searching for carbon dioxide as a possible lead to carbon-based life-forms. Never mind what Stephen Hawking has to say about that.


The horizon of Proxima B as imagined by one artist.

CO2 doesn’t even mean the existence of something that could survive on Earth. Our planet is crawling with carbon-based life, and yet there are only traces of the gas among the dominant nitrogen and oxygen of the atmosphere. Ironically enough, it’s common in the killer atmosphere of Venus and on Mars, which only has a ghost of an atmosphere.  

JWST will revolutionize how we observe Proxima B and many other celestial objects and phenomena. This is what you get with an instrument that has been optimized to pick up infrared wavelengths invisible to the naked eye—and most other telescopes.

“Other telescopes are not able to do this,” said University of Leiden astronomy researcher Ignas Snellan, lead author of a study recently published in the Astrophysical Journal. “Hubble is too small and works in the wrong wavelength range. Current ground-based telescopes cannot touch the mid-infrared because of very high thermal backgrounds, and are in a not enough stable environment, in contrast to JWST, which operates from space.”

Whether there is life on Proxima B might not even be a question that the JWST can answer. If it still remains a mystery within the next decade or so, the European Extremely Large Telescope that is currently being built will at least be able to detect oxygen, a more reliable biosignature.

Oxygen still doesn’t mean aliens. We’ll just have to wait and see what observations these massive telescopes transmit to Earth. 

(via Seeker)

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