Watch this very cool video of the ginormous James Webb Space Telescope unfolding its 18 gold-plated hexagonal mirrors! https://www.syfy.com/syfywire/watch-as-the-james-webb-telescope-unfolds-its-18-gold-plated-hex-mirrors

2/ Each one of those hexagons is 1.3 meters across. The gold is highly reflective in infrared, which is what JWST is designed to see, and it was deposited by vaporizing the gold and depositing it on a substrate. The gold layer is only 0.1 microns thick!

3/ A human hair is about 100 microns thick, so *1000* times thicker than that gold layer. An extremely thin layer of silicon dioxide glass is then deposited on top to prevent the gold from getting scratched.

4/ The gold is so reflective the mirrors are hard to see up close. When they were finished at Ball Aerospace in Boulder, CO in 2012, they invited local sci folks to come see, including me. I got some interesting photos. This is thru a window in a door. Note the dork on the right.

5/ By the by, JWST will not “replace” Hubble. They do two different kinds of observations. JWST sees much farther in the infrared than Hubble.

If Hubble is still operational when JWST flies, they’ll complement each other.