After 20 Years, NASA Finally Finished Building The James Webb Space Telescope | Popular Science
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After 20 Years, NASA Finally Finished Building The James Webb Space Telescope

Now it's ready for the final tests before launch in 2018

James Webb Space Telescope

Engineers are ready to conduct a series of tests on the completed James Webb Space Telescope.

NASA/Chris Gunn

Twenty years ago, scientists began assembling a next-generation telescope that would be the successor for the Hubble. Now, NASA engineers have announced that construction of the James Webb Telescope (JWST) is finally complete. The telescope, which is twice the size of Hubble with a 21-foot mirror, is ready for testing before its scheduled launch in October 2018.

"Today, we're celebrating the fact that our telescope is finished, and we're about to prove that it works," said John Mather, an astrophysicist and senior project scientist for the telescope at a news conference reported by Space.com.

Inspired by the success of the Hubble Space Telescope, NASA and its European and Canadian counterparts collaborated on the design and construction of the JWST. The resulting telescope is bigger and more powerful than the Hubble, giving it the ability to see the first galaxies born after the Big Bang. The observations it makes will not only help scientists understand the origins of the universe, but also search for signs of life on faraway planets.

By looking at infrared light given off by all objects in space, the unmanned telescope will pull back the curtains of the universe and see stars too distant even for the Hubble. Eighteen large hexagonal mirrors, made out of lightweight berylium and coated with gold will collect the infrared readings for the JWST. They’ll operate at close to absolute zero temperatures, from a point in space called the Lagrange Point 2, which is directly behind Earth from the sun's perspective.

But to ensure the telescope will work in space, NASA needs to put it through a series of rigorous tests.

First, scientists at the Goddard Space Center in Maryland will shake the vehicle and blast it with about 150 decibels of violent noise to simulate the rough conditions it’ll experience during launch. Then, the mirror and instruments will be shipped to the Johnson Space Center in Houston for some cryogenic testing, to ensure it can withstand the frigid conditions of space. Once that work is done, engineers will attach the telescope to the spacecraft bus, which incorporates elements such as the flight computers and communications system. Finally, James Webb will be given a tennis-court-sized shield to protect its delicate instruments from the Sun and undergo even more testing to make sure its measurements are not out of whack before it launches.

By the time the telescope is finally shipped to French Guiana for its launch on top of the European Ariane 5 rocket, the total cost is expected to reach $10 billion. So far, the telescope is on schedule and on budget, but each stage of the upcoming testing must go exactly according to plan. Unlike with Hubble, astronauts won’t be able to reach the JWST to fix a problem after it launches. The telescope will be stationed too far away for them to reach — about 930,000 miles from Earth.

Once it is in position, though, together the James Webb and Hubble will give scientists an unprecedented view of the universe.

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