Though it is still two to three years away from launch, the James Webb Space Telescope
is shaping up to be a technological wonder. Once in place, it will be the first optical telescope in orbit and will sport a primary mirror six times larger than that of the Hubble, seeing further and clearer using infrared optics. But to do all that, the Webb telescope will use a massive sunshield the size of a tennis court.
The Webb sunshield will consist of five separate layers of Kapton, folded at launch and then stretched over 20 x 12 meters. The mutliple layers of this strong, durable film are what give the sunshield its amazing properties:
Once on orbit, the sunshield creates a 330 K (243°F to -351°F) temperature differential between the hottest and coldest layers. Using multiple separated layers allows most of a layer’s heat to radiate to space before it reaches the next one creating a substantial temperature drop from one layer to the next.
All together, these layers give the sunshield an effective Sun Protection Factor (SPF) of 1,000,000, according to the Deputy Project Manager for the telescope, John Durning
. Such protection is necessary as the onboard infrared systems are sensitive to heat, and must be kept at very low temperatures -- under -370 F, or 50 K.
Though the pictures from visible light telescopes are beautiful, many are limited because the visible spectrum of light cannot penetrate the dust and gas that floats around the galaxy. With the Webb telescope, scientist will see some of the oldest, most distant stars thanks to infrared imaging, giving them a better understanding of the Universe's origins.
(NASA, Webb Telescope via The Universe Today)