The video was filmed at NASA Goddard's clean room and shows the procedure of the mirror placement on the backplane. The 90 second video features John Amon, Manufacturing Engineer from ITT Exelis, Rochester, N.Y. The video is available in high resolution at NASA's Scientific Visualization Studio website.
Designing and building the actual backplane that will hold the 18 individual mirror segments that make up Webb's 21.3 foot (6.5 meter) diameter primary mirror has been a real engineering challenge. The backplane has to keep Webb's mirror segments precisely aligned to one another at extremely cold temperatures in space after being violently shaken during launch aboard a rocket. It is a truss structure consisting primarily of very lightweight but very stiff and strong square-shaped, thin-walled tubes made of a special composite material.
The actual mirror segments are made of beryllium, which is a very lightweight and stiff metal that is dimensionally stable at the Webb telescope's cryogenic operating temperature of roughly minus 390 degrees Fahrenheit. The reflecting surface of each flight mirror segment is coated with an extremely thin layer of pure gold to better reflect the infrared light that Webb is designed to capture.
Engineers at the Goddard Space Flight Center test the robotic-like fixture that will place the primary mirror segments of the Webb Telescope onto the telescopes back plane.
(Photo Credit: NASA's Goddard Space Flight Center)
A surrogate mirror segment which is the same hexagonal shape and same mass or weight as one of the primary flight mirrors, is being carefully attached to the a test structure called a "backplane" that will hold 18 of those mirrors on the Webb telescope.
(Photo Credit: NASA/Chris Gunn)
Source: NASA/Goddard Space Flight Center