JWST’s Giant Golden Mirror is Unveiled

As part of the integrating and testing of the James Webb Space Telescope (JWST), NASA engineers have unveiled the giant golden mirror of the IR telescope — it is heralded as the largest mirror yet sent into space.

The 18 mirrors that make up the primary mirror were individually protected with black covers when they were assembled on the telescope structure, and now, for the first time since the primary mirror was completed, the covers have been lifted.

Each mirror is made of strong, light beryllium, and each mirror segment is about the size of a coffee table and weighs approximately 20 kg. A very fine film of vaporized gold coats each segment to improve the mirror's reflection of IR light. The fully assembled mirror is larger than any rocket, so the two sides of it fold up. Behind each mirror are several motors so that the team to enable focusing in space.

JWST will be used to capture images and spectra of the first galaxies to appear in the early universe, over 13.5 billion years ago, as well as the full range of astronomical sources such as star-forming nebulae, exoplanets, and even moons and planets within Earth’s solar system.

The telescope is targeted to launch from French Guiana aboard an Ariane 5 rocket in 2018. The international project is led by NASA in partnership with the European and Canadian space agencies.

Photonics Media covered the arrival of the mirror segments back in 2013.