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Testing the James Webb Space Telescope's primary mirror

Credit: NASA/Chris Gunn

The James Webb Space Telescope's Sunshield

Credit: Northrop Grumman

Construction of the James Webb Space Telescope is now complete!

On October 31, NASA completed the construction of the James Webb Space Telescope by adding the final layer of the telescope's gigantic sunshield. The sunshield is made of five layers, each as thin as a human hair, that will block out heat from the sun and help keep the telescope's science instruments cool.

Extensive testing has now begun on the telescope to prove that it will work in space. On November 2, NASA conducted the first of several tests of the Webb's giant primary mirror to ensure its integrity and accuracy.

Next, the observatory will be put through tests that simulate the rigours of launch, after which the mirror will be tested again to compare the results and see if there are any changes or damage.