The JWST will 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. The primary mirror of the JWST, the Optical Telescope Element, is composed of eighteen 1.32 metres hexagonal mirror segments made of gold-plated beryllium which combine to create a 6.5 metres diameter mirror that is considerably larger than the Hubble’s 2.4 metres mirror. Unlike the Hubble, which observes in the near ultraviolet, visible, and near infrared (0.1 to 1 μm) spectra, the 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 the 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 Earth–Sun L2Lagrangian point, and a large sunshield made of silicon-coated and aluminium-coated Kapton will keep its mirror and instruments below 50 Kelvin (K). The JWST is being developed by NASA — with significant contributions from the European Space Agency and the Canadian Space Agency — and is named for James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program. The prime contractor is Northrop Grumman. Development began in 1996 for a launch that was initially planned for 2007 and a 500-million-dollar budget, but the project has had numerous delays and cost overruns, and underwent a major redesign in 2005. The JWST’s construction was completed in late 2016, after which its extensive testing phase began. The launch date was Dec. 25, 2021.
