The One and Only (AFAIK)
I never realised how big the mirror is compared to Hubble!
It would be a nice opening mission for a crewed Orion though: The first JWST repair mission
Title Inspecting JWST’s primary mirror
Released 21/11/2016 10:46 am
Copyright NASA–C. Gunn
Before a spacecraft goes into space it must undergo rigorous testing to confirm it can withstand the violent vibrations and sounds during launch.
For the powerful 6.5 m-diameter telescope of the James Webb Space Telescope, or JWST, making the same measurements both before and after a simulated launch is a vital part of confirming its optics will not be adversely affected by the real launch.
In a recent ‘before’ test, engineers made highly precise measurements of the shape of the main mirror in a ‘centre of curvature’ test.
http://sci.esa.int/jwst/58666-10-the-observatory-is-assembled/#10: The observatory is assembled
21 December 2016 10:34
With less than two years remaining before its scheduled launch, the James Webb Space Telescope (JWST) has passed several major milestones, including the completion of its huge primary mirror and integration of its four science instruments with the payload module.
http://sci.esa.int/jwst/58672-11-preparing-for-the-ride-to-space/#11: Preparing for the ride to space
21 December 2016 14:45
In the second half of 2016, the James Webb Space Telescope (JWST) was readied for an intensive series of environmental tests, an essential step in ensuring that it will survive the stresses of launch and complete its groundbreaking survey of the infrared sky.
The James Webb Space Telescope is pushed into the clean room of Building 32. Building 32 houses Chamber A, the thermal vacuum chamber where the telescope will have its final thermal vacuum testing. Credits: NASA/Chris Gunn
NASA's James Webb Space Telescope has arrived at NASA’s Johnson Space Center in Houston, Texas, where it will undergo its last cryogenic test before it is launched into space in 2018.
The biggest and final cryogenic-vacuum test occurs in Johnson's Chamber A, the same vacuum chamber where Apollo spacecraft were tested. This test is critical in that it will verify the performance of the whole telescope as a system end-to-end at its extremely cold operating temperatures. Subsequently, the telescope will continue on its journey to Northrop Grumman Aerospace Systems in Redondo Beach, California, for final assembly and testing with the spacecraft bus and sunshield prior to launch in 2018.