From NASA: “Tests Under way on the Sunshield for NASA’s Webb Telescope”
The five-layer James Webb Space Telescope sunshield consists of thin membranes made from a polymer-based film and supporting equipment such as spreader bars, booms, cabling, and containment shells. Designed to block solar light and keep the Observatory operating at cryogenic temperatures. Credit: NASA/Northrop Grumman
The sunshield will consist of five tennis court-sized layers to allow the Webb telescope to cool to its cryogenic operating temperature of minus 387.7 degrees Fahrenheit (40 Kelvin). ”
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