Inside the Cleanroom of NASA’s James Webb Space Telescope

by Thaddeus Cesari ​- NASA's Goddard Space Flight Center

The James Webb Space Telescope will observe primarily the infrared light from faint and very distant objects. In order to be able to detect those faint heat signals, the telescope itself must be kept extremely cold. To protect the telescope from external sources of light and heat (like the Sun, Earth, and Moon) as well as from heat emitted by the observatory itself