This artist’s concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Credit: NASA/JPL-Caltech
With the discovery of seven earth-sized planets around the TRAPPIST-1 star 40 light years away, astronomers are looking to the upcoming James Webb Space Telescope to help us find out if any of these planets could possibly support life. “If these planets have atmospheres, the James Webb Space Telescope will be the key to unlocking their secrets,” said Doug Hudgins, Exoplanet Program Scientist at NASA Headquarters in Washington. “In the meantime, NASA’s missions like Spitzer, Hubble, and Kepler are following up on these planets.”
“These are the best Earth-sized planets for the James Webb Space Telescope to characterize, perhaps for its whole lifetime,” said Hannah Wakeford, NASA’s Goddard Space Flight Center in Greenbelt, Maryland. At Goddard, engineers and scientists are currently testing the Webb telescope which will be able to view these planets in the infrared, beyond the capabilities we currently have. “The Webb telescope will increase the information we have about these planets immensely. With the extended wavelength coverage we will be able to see if their atmospheres have water, methane, carbon monoxide/dioxide and/or oxygen.”
Launching in 2018, one of Webb’s main goals is to use spectroscopy, a method of analyzing light by separating it into distinct wavelengths which allows one to identify its chemical components to determine the atmospheric components of alien worlds. Webb will especially seek chemical biomarkers, like ozone and methane, that can be created from biological processes. Ozone, which protects us from UV here on Earth, forms when oxygen produced by photosynthetic organisms (eg trees and phytoplankton) synthesizes in light. As ozone is largely dependent on organisms to form, Webb will look for it in alien atmospheres as a possible indicator of life. It will also be able to look for methane which will help determine a biological source of the oxygen that leads to ozone accumulation.
The discovery of the planets in the TRAPPIST-1 system means that Webb will be able to use its immense capabilities on a relatively nearby system. Researchers recently identified 3 promising planets in the TRAPPIST-1 system – e, f and g – which orbit in the habitable zone and would make good candidates for Webb to study. Depending upon their atmospheric composition, all 3 of these Earth-like exoplanets could have the appropriate conditions for supporting liquid water. Because the planets orbit a star that is small, the signal from those planets will be relatively large, and just strong enough for Webb to detect atmospheric features.
The number of planets in the system will also enable new research in the field of comparative planetology,. “This is the first and only system to have 7 earth-sized planets, where 3 are in the habitable zone of the star,” said Wakeford. “It is also the first system bright enough, and small enough, to make it possible for us to look at each of these planets’ atmospheres. The more we can learn about exoplanets, the more we can understand how our own solar system came to be the way it is. With all seven planets Earth-sized, we can look at the different characterisitics that make each of them unique and determine critical connections between a planet’s conditions and origins.”
We’re looking to answer age-old questions, like how did our universe begin and evolve; how did galaxies, stars, and planets come to be; and are we alone. https://www.nasa.gov/feature/goddard/2017/probing-seven-worlds-with-nasas-james-webb-space-telescope
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