Larkin Carey, Technician at Ball Aerospace, can be seen carefully removing Webb’s “lens cap” from the Aft Optics subsystem, keeping the observatory’s sensitive instruments clean, free of contaminants and protected from stray light throughout the integration and testing process. NASA / Chris Gunn
The troubled James Webb Telescope has suffered a long series of delays but is finally creeping towards its launch as it recently completed several milestones in its final round of testing. The NASA observatory will be the successor to the Hubble telescope and will study everything from exoplanets to black holes once it is launched into orbit.
The telescope has now reached three milestones in its final round of testing prior to its scheduled launch later this year.
First the “lens cap” of the telescope was removed. Technically known as the cover for the rear optics subsystem, this part protects the instruments during the assembly and preparation phase and prevents them from becoming soiled by debris. In the picture at the top of this page, you can see Technician Larkin Carey removing the cover so the rest of the hardware can be folded up for his journey into space.
Second, Webb has a tower that can be telescoped up to three meters to keep the mirrors and instruments separate from the sun-facing side of the observatory. This is to keep the instruments cool so that solar heat fluctuations do not affect their readings. The tower was recently erected for the last time to check that it is ready for later use in space.
Third, the telescope needs to be folded into a small volume to fit inside the Ariane 5 rocket that will put it into orbit. This requires a complex system of folding parts, especially for large items such as the tennis court-sized sun visor. The folded sun visor sits on a support called the unitary pallet structure, and now that the lens cap has been removed the pallet is also collapsed for start-up.
These tests were conducted at a Northrop Grumman facility in Redondo Beach, California. Once all of the final tests are completed, the telescope will be folded and stowed one final time before it is shipped to Kourou, French Guiana, to be launched in November 2021.