Behind the Webb Video Podcast

The James Webb Space Telescope features a mirror 21.3 feet (6.5 m) across, with nearly seven times the area of the famed Hubble Space Telescope. In order to launch something this size, NASA designed the primary mirror to consist of 18 separate, hexagon-shaped mirrors that will fold up inside the rocket that carries the telescope into space. The mirror components are being tested both individually and together. A specially designed vacuum chamber at Marshall Space Flight Center simulates the extreme conditions of spa, subjecting the mirror segments to temperatures as low as 400 degrees below zero.

Related links:

Webb Technology Challenge: Make it Big

Webb Technology Challenge: Keep it Cold

Outside links:

NASA image gallery: NASA Chills: James Webb Space Telescope Mirrors Are Readied for Test

NASA news release: Mirror Testing at NASA Breaks Superstitious Myths