NASA engineers have been working tirelessly over the last few months, painstakingly assembling the James Webb Telescope's huge primary mirror. This week marks a significant milestone in the project, with the the last of the 18 individual segments now in place.

We first heard confirmation that the assembly of the primary mirror had begun when the first segment was put in place at the end of November 2015, in a clean room at NASA's Goddard Space Flight Center in Maryland. Since then, 17 additional segments have been put in place using a robot arm, with the construction phase finally completed on February 3, with the successful placement of the last piece.

Each panel of hexagonal-shaped mirror measures slightly over 4.2 ft (1.3 m) across, and weighs some 88 lb (40 kg). Once deployed, all 18 segments will operate as a single. 21.4-ft (6.5-m) mirror, at which point the Hubble successor will get to work studying the formation of solar systems with the potential to support life, the evolution of our own solar system, and much more.

While the primary mirror is now complete, there's a lot more to do before the telescope's scheduled launch in 2018, including the construction of the secondary mirror, and various acoustic and vibration tests.

"Now that the mirror is complete, we look forward to installing the other optics and conducting tests on all the components to make sure the telescope can withstand a rocket launch," said project manager Bill Ochs. "This is a great way to start 2016!"

Source: NASA

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