James Webb Space Telescope sunshield
component of the James Webb Space Telescope
The James Webb Space Telescope (JWST) sunshield is a passive thermal control system deployed post-launch to shield the telescope and instrumentation from the light and heat of the Sun, Earth, and Moon. By keeping the telescope and instruments in permanent shadow, it allows them to cool to their design temperature of 40 kelvins (−233 °C; −388 °F). Its intricate deployment was successfully completed on January 4, 2022, ten days after launch, when it was more than 0.8 million kilometers (500,000 mi) away from Earth.
The JWST sunshield is about 21 m × 14 m (69 ft × 46 ft), roughly the size of a tennis court, and is too big to fit in any existing rocket. Therefore, it was folded up to fit within the fairing of the launch rocket and was deployed post-launch, unfolding five layers of metal-coated plastic. The first layer is the largest, and each consecutive layer decreases in size. Each layer is made of a thin (50 microns for the first layer, 25 microns for the others) Kapton membrane coated with aluminum for reflectivity. The outermost Sun-facing layers have a doped-silicon coating which gives it a purple color, toughens the shield, and helps it reflect heat. The thickness of the aluminum coating is approximately 100 nanometers, and the silicon coating is even thinner at approximately 50 nanometers. The sunshield segment includes the layers and its deployment mechanisms, which also includes the trim flap.
“James Webb Space Telescope sunshield” enters the record as component of the James Webb Space Telescope. Crown Archives preserves that source wording while asking what James, Webb and Space can confirm, complicate or overturn.
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This entry incorporates text from “James Webb Space Telescope sunshield” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.