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First exoplanet targets recommended for Webb observation

Size comparison of Kepler-442b with Earth. This is a potential candidate for first exoplanet observation by the James Webb Space Telescope. Credit: Helgo13

Size comparison of Kepler-442b with Earth. This is a potential candidate for first exoplanet observation by the James Webb Space Telescope. Credit: Helgo13

Now that the James Webb Space Telescope’s primary mirror has been aligned successfully, scientists are identifying the first exoplanets for the telescope to observe.

On March 21, NASA announced the milestone of 5,005 confirmed exoplanets. One of JWST‘s major tasks will be studying the atmospheres of exoplanets to look for signs of life.

Canadian astronaut Chris Hadfield recommended Kepler-442b, a likely rocky world in its star’s habitable zone as an ideal first planetary target for the new infrared telescope.

Located around 1,200 light years from Earth in the constellation Lyra, Kepler-442b was discovered by NASA’s Kepler and K2 missions. The planet orbits a K-type star 40 times less massive than our Sun and has an orbital period of 112 days. With a radius 1.34 times that of Earth, it is a super-Earth and one of the most promising worlds in terms of possibly hosting life.

Hadfield selected this planet based on a 2015 study in The Astrophysical Journal, in which a team of scientists ranked planets discovered by Kepler and K2 for being most likely to have liquid water on their surfaces. Kepler-442b was one of the planets the study identified.

“Basically, we’ve devised a way to take all the observational data that are available and develop a prioritization scheme, so that as we move into a time when there are hundreds of targets available, we might be able to say, ‘Ok, that’s the one we want to start with,'” paper lead author Rory Barnes of the University of Washington said in 2015.

Based on their ranking system, some scientists believe Kepler-442b is actually more habitable than the Earth.

“We ranked the known Kepler and K2 planets for habitability and found that several have larger values of H [the probability of being terrestrial] than Earth,” the paper’s authors wrote.

Another top planetary target for JWST is the TRAPPIST-1 system, located just 41 light years from Earth, which hosts seven planets in very tight orbits around a low-mass red dwarf star. Three or four of these planets are located in the star’s habitable zone. All seven are believed to be rocky worlds.

JWST will study the planets’ atmospheres and identify their components. In its search for signs of life, the telescope may be powerful enough to detect atmospheric pollution produced by intelligent civilizations.

“The optical performance of the telescope is absolutely phenomenal. The performance is as good, if not better, than our most optimistic predictions,” said JWST optical telescope manager Lee Feinberg of NASA’s Goddard Space Flight Center after JWST captured a sharp image of the star 2MASS J17554042+6551277 earlier this month.

Current plans call for JWST science operations to start in late June.

Video courtesy of NASA


Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.

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