James Webb Space Telescope Testing Milestone The James Webb
Space Telescope completes first round of cryogenic mirror test
The first six of 18 segments that will form NASA’s James Webb
Space Telescope’s primary mirror for space observations
completed final cryogenic testing on Friday. The ten week test
series included two tests cycles where the mirrors were chilled
down to -379 degrees Fahrenheit, then back to ambient
temperature to ensure the mirrors respond as expected to the
extreme temperatures of space. A second set of six mirror
assemblies will arrive at Marshall in late July to begin
testing, and the final set of six will arrive in the fall. The
X-ray and Cryogenic Facility at NASA’s Marshall Space Flight
Center in Huntsville, Ala. provides the space-like environment
to help engineers measure how well the telescope will image
infrared sources once in orbit. Each mirror segment measures
approximately 4.3 feet (1.3 meters) in diameter to form the 21.3
foot (6.5 meters), hexagonal telescope mirror assembl