After more than 20 years of construction, the James Webb Space Telescope (JWST) is complete and, following in-depth testing, the largest-ever space telescope is expected to launch within two years, NASA officials announced on 2nd November 2016.
NASA Administrator Charles Bolden hosted a news conference to announce the milestone this morning at the agency’s Goddard Space Flight Center in Maryland, overlooking the 18 large mirrors that will collect infrared light, sheltered behind a tennis-court-size sun shield. JWST is considered the successor to NASA’s iconic Hubble Space Telescope.
“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. “We’ve done two decades of innovation and hard work, and this is the result — we’re opening up a whole new territory of astronomy.
The telescope will be much more powerful than even Hubble for two main reasons, Mather said at the conference. First, it will be the biggest telescope mirror to fly in space. “You can see this beautiful, gold telescope is seven times the collecting area of the Hubble telescope,” Mather said. And second, it is designed to collect infrared light, which Hubble is not very sensitive to.
JWST will run close to absolute zero in temperature and rest at a point in space called the Lagrange Point 2, which is directly behind Earth from the sun’s perspective. That way, Earth can shield the telescope from some of the sun’s infrared emission, and the sun shield can protect the telescope from both bodies’ heat.
The telescope’s infrared view will pierce through obscuring cosmic dust to reveal the universe’s first galaxies and spy on newly forming planetary systems. It also will be sensitive enough to analyze the atmospheres of exoplanets that pass in front of their stars, perhaps to search for signs of life, Mather said.
The telescope was originally scheduled to launch in 2014, at a cost of about $5 billion, but a series of setbacks and budget constraints delayed and nearly canceled the project. Now, though, officials affirmed that the telescope is on track and on budget for an October 2018 launch on an Ariane 5 rocket. (As a result of the delays, JWST’s cost is now $8.7 billion, Ochs said.) The project is led by NASA but supported by international partners, including the European Space Agency and the Canadian Space Agency.
The telescope’s testing at Goddard, which has already begun, will ensure that it can withstand the shaking and loud noise of a rocket launch. Then, it will be moved to Texas, where its focus will be tested, and then to California for some final assembly. The testing is particularly high-stakes, because unlike Hubble, which was repaired and refocused in orbit by astronauts, this telescope is not intended to be repaired by humans.
The full telescope, with a 21.3-foot (6.5 meters) mirror assembly, is too large to launch fully extended, so the telescope will be carefully furled during launch and will have to unfold over the course of two weeks once it’s in space, Mather said. After that, the sun shield will be extended carefully, and the telescope will be given time to cool down. Finally, it will be focused, they said.
By six months after launch, the telescope will be ready to begin doing science.