English: The world’s most powerful space science telescope has opened its primary mirror for the last time on Earth.

As part of the NASA’s James Webb Space Telescope’s final tests, the 6.5 meter (21 feet 4 inch) mirror was commanded to fully expand and lock itself into place, just like it would in space. The conclusion of this test represents the team’s final checkpoint in a long series of tests designed to ensure Webb’s 18 hexagonal mirrors are prepared for a long journey in space, and a life of profound discovery. After this, all of Webb’s many movable parts will have confirmed in testing that they can perform their intended operations after being exposed to the expected launch environment.

Making the testing conditions close to what Webb will experience in space helps to ensure the observatory is fully prepared for its science mission one million miles away from Earth.

Commands to unlatch and deploy the side panels of the mirror were relayed from Webb’s testing control room at Northrop Grumman, in Redondo Beach, California. The software instructions sent, and the mechanisms that operated are the same as those used in space. Special gravity offsetting equipment was attached to Webb to simulate the zero-gravity environment in which its complex mechanisms will operate. All of the final thermal blanketing and innovative shielding designed to protect its mirrors and instruments from interference were in place during testing.

Read more: www.nasa.gov/feature/goddard/2021/webb-s-golden-mirror-wi...

Image credit: NASA/Chris Gunn