Half as big as a 737 aircraft and with a sun shield about the size of a tennis court, NASA's $10bn James Webb Space Telescope (JWST) is an orbiting infrared observatory that complements and extends the discoveries of the Hubble Space Telescope, with longer wavelength coverage and greatly improved sensitivity. Launched on Christmas Day 2021 and positioned nearly a million miles from Earth, its large mirror enables it to observe some of the first galaxies that formed a few hundred million years after the Big Bang, roughly 13.8 billion years ago.

This article looks at the abilities and primary mission goals for JWST, together with the technology behind its key components such as the segmented primary mirror and its special multi-layer sunshield.