The James Webb Space Telescope has to be kept at bitterly cold
temperatures for its sensitive instruments to work. Each step of
the way, engineers must counter Webb's ordinary, everyday heat
production with a method of dropping the temperature ever lower
WHY AN INFRARED TELESCOPE? The Webb telescope sees in infrared
light, a wavelength that warm objects emit in large amounts. We
look for infrared light for several reasons. First, the light
from the most distant objects in the universe — objects that
existed just 200 million years after the Big Bang — has been
stretched as it travels through the expanding universe. The
stretching changes the light, moving it from the visible range
into invisible infrared. Second, infrared light can pierce the
dust that blocks visible light emissions, allowing us to peer
through clouds of dust to the warm objects within. Finally, warm
objects that don't emit their own visible light, such as
planets, do emit infrared, making them viewable with the right
tools. But infrared light