The golden eye peering through the cosmic dust of our early universe
To see the first galaxies, we had to build a telescope that functions like a giant, origami-folded heat shield. Positioned one million miles from Earth, the James Webb Space Telescope uses infrared vision to pierce through dense dust clouds and capture light from the universe's infancy.
Launched on December 25, 2021, the James Webb Space Telescope (JWST) is an international collaboration between NASA, the ESA, and the CSA [S1:p1, S3:p3]. Unlike visible light telescopes, Webb operates in the infrared spectrum, a wavelength that allows it to see through thick cosmic dust and smoke [S2:p3, S2:p4]. This capability is essential for observing the birth of stars and planets inside nebulous clouds, as well as detecting light from the very first galaxies that formed roughly 200 million years after the Big Bang [S2:p2, S2:p4].
The telescope's engineering is a feat of extreme precision and scale. Because it is too large to fit inside a standard rocket, the observatory was designed to fold 'origami-style' [S2:p3, S4:p2]. Its primary mirror, a 6.5-meter structure composed of 18 lightweight beryllium segments, unfolds in orbit [S3:p2, S3:p3]. These segments are coated in a thin layer of gold, which optimizes the reflection of infrared light [S2:<0xE2><0x80><0x8A>p6, S4:p7].
Maintaining the extreme cold required for its instruments is equally critical. Webb utilizes a five-layer, tennis-court-sized sunshield to protect its sensitive mirrors from solar heat [S3:p3]. This shield attenuates heat from the Sun by more than a million times, creating a staggering temperature differential of over 600 degrees Fahrenheit between the sun-facing and shaded sides [S2:p5, S3:p3]. To further ensure accuracy, instruments like MIRI utilize a cryocooler to reach temperatures as low as 7 kelvins [S3:p4].
Source: What Will the James Webb Space Telescope See Out There?
