The JWST Shield

February 18, 2024

Imagine observing the faint whispers of light from the first galaxies, billions of light-years away. JWST operates in the infrared spectrum, where faint cosmic signals reside. Any heat from our celestial neighbors would drown out these faint whispers, making observations impossible. For the James Webb Space Telescope to function properly, it needs a unique and powerful protector: the sunshield.

Think of the sunshield as a giant umbrella, roughly the size of a tennis court. This marvel of engineering is made of five ultra-thin layers of a special material called Kapton that is coated with reflective aluminum. On the sun-facing side of the two hottest layers, a doped silicon coating is used to reflect the sun's heat back into space. Its purpose is to shield the telescope and its delicate instruments from the harsh light and heat of the Sun, Earth, and Moon.

To get the shield in place, it is first folded origami-style within the launch rocket, then once in position, the sunshield deploys in a sequence like a blooming flower. Motors and pulleys carefully extend each layer, ensuring a smooth and tensioned structure. Once operational, the sunshield constantly adjusts its position, like a loyal bodyguard, ensuring the telescope remains in permanent shadow. This allows the instruments to cool down, creating the perfect environment to capture faint infrared light from distant stars, galaxies, and even exoplanets.

Learn more at NASA's Goddard Space Flight Center.

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