The huge mirror of NASA's James Webb Space Telescope -- its successor to Hubble -- has been successfully tested for the first time, putting it one step closer to its eventual launch, which is slated for 2021. Like Hubble -- which has long outlived its original lifespan but is expected to remain operational for a few years yet -- the James Webb will investigate celestial bodies from our solar system and beyond.
Getting the new telescope to this stage has been a challenging endeavor for NASA -- its launch was initially scheduled for 2018, but the intricacy of construction, number of parts needed and the fact that it's the most complex telescope built to date meant its launch date has seen a series of delays.
Now though, following the successful test, researchers are confident it's on track for launch next year. The test procedure involved replicating Webb's final configuration in a space-like environment. This meant replicating the zero-gravity atmosphere Webb will eventually operate in, using special gravity-offsetting equipment. The spacecraft's internal systems were then used to fully extend and latch Webb's 21-foot primary mirror, to appear as it will after it's been launched into orbit. Because the mirror is so large, it can't fit inside any available rocket, so it's comprised of a series of moveable parts that designed to fold in on themselves.
Tests like these help safeguard both the spacecraft and telescope, but the primary mirror will only be deployed once more on the ground -- just before Webb is taken to its launch site. In a statement to Parabolic Arc, Webb's optical telescope element manager, Lee Feinberg, said, "Deploying both wings of the telescope while part of the fully assembled observatory is another significant milestone showing Webb will deploy properly in space. This is a great achievement and an inspiring image for the entire team."