An orbiting infrared observatory that will take the place of the Hubble Space Telescope. It will study the Universe as it appeared when galaxies were forming during the first billion years or so after the Big Bang. As light from such great distances is subjected to very high redshift, such observations are best performed in the infrared. The JWST will be capable of detecting radiation at wavelengths from 0.6 to 28 microns. In addition, it will be able to see objects 400 times fainter than those visible to the largest ground-based infrared telescopes or the current generation of space-based infrared telescopes, and with a resolution comparable to the Hubble Space Telescope (HST).

To achieve these objectives, JWST will have a beryllium mirror 6.5 m in diameter consisting of 18 hexagonal segments. The mirror will be folded for launch, as will the large sunshield, the size of a tennis court, that will shade it from the Sun's rays once in space. It will be equipped with an infrared camera and spectrometer. The JWST will be positioned at the L2 Lagrangian point of the Earth's orbit, 1.5 million km from Earth on the side away from the Sun.

The telescope is named after James E. Webb, a former NASA administrator. It is being built by NASA with contributions from ESA and Canada and launched from French Guiana December 2021.

Engineers at NASA’s Goddard Space Flight Center pose with the James Webb Space Telescope.

Credit: NASA, Goddard Space Flight Center

http://www.jwst.nasa.gov/ Official NASA site chronicling the development of the telescope and its instruments, with a summary of the questions in cosmology it is designed to address.