English: Six of the 18 James Webb Space Telescope mirror segments are being prepped to move into the X-ray and Cryogenic Facility, or XRCF, at NASA's Marshall Space Flight Center in Huntsville, Ala., to eventually experience temperatures dipping to a chilling -414 degrees Fahrenheit to ensure they can withstand the extreme space environment. The test chamber takes approximately five days to cool a mirror segment to cryogenic temperatures. Marshall's X-ray & Cryogenic Facility is the world's largest X-ray telescope test facility and a unique, cryogenic, clean room optical test location.