The James Webb Space Telescope (JWST) is a space telescope developed by NASA with contributions from the European Space Agency (ESA) and the Canadian Space Agency (CSA). It is planned to succeed the Hubble Space Telescope as NASA’s flagship mission in astrophysics. JWST was launched on 25 December 2021 on Ariane flight VA256. It is designed to provide improved infrared resolution and sensitivity over Hubble, and will enable a broad range of investigations across the fields of astronomy and cosmology, including observing some of the most distant events and objects in the universe, such as the formation of the first galaxies, and providing detailed atmospheric characterization of potentially habitable exoplanets.
The primary mirror of JWST, the Optical Telescope Element, consists of 18 hexagonal mirror segments made of gold-plated beryllium which combine to create a 6.5 m (21 ft) diameter mirror – considerably larger than Hubble’s 2.4 m (7 ft 10 in) mirror. Unlike the Hubble telescope, which observes in the near ultraviolet, visible, and near infrared (0.1 to 1 μm) spectra, JWST will observe in a lower frequency range, from long-wavelength visible light through mid-infrared (0.6 to 28.3 μm), which will allow it to observe high redshift objects that are too old and too distant for Hubble to observe. The telescope must be kept very cold in order to observe in the infrared without interference, so it will be deployed in space near the Sun–Earth L2 Lagrange point, about 1.5 million kilometres (930,000 mi) from Earth (0.01 au – 3.9 times the distance to the Moon). A large sunshield made of silicon– and aluminum-coated Kapton will keep its mirror and instruments below 50 K (−223 °C; −370 °F).
The NASA Goddard Space Flight Center (GSFC) in Maryland is managing the development effort, and the Space Telescope Science Institute will operate Webb after launch. The prime contractor is Northrop Grumman. The telescope is named after James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program.