James Webb
The James Webb Space Telescope (JWST) is a space telescope designed primarily to conduct infrared astronomy. The U.S. National Aeronautics and Space Administration (NASA) led development of the telescope[8] in collaboration with the European Space Agency (ESA) and the Canadian Space Agency (CSA).[9] The JWST was launched 25 December 2021 on an ESA Ariane 5 rocket from Kourou, French Guiana[10] and is intended to succeed the Hubble Space Telescope as NASA’s flagship mission in astrophysics.[11][12] The telescope[13] is named after James E. Webb,[14] who was the administrator of NASA from 1961 to 1968 during the Mercury, Gemini, and much of the Apollo programs.[15][16]
With greatly improved infrared resolution and sensitivity, it will view objects too old and distant for Hubble—some up to 100 times fainter.[17][18][19] This is expected to enable a broad range of investigations across the fields of astronomy and cosmology, such as observations of first stars and the formation of the first galaxies, as well as detailed atmospheric characterization of potentially habitable exoplanets.
JWST’s primary mirror, the Optical Telescope Element, consists of 18 hexagonal mirror segments made of gold-plated beryllium which combine to create a 6.5-meter (21 ft)[20] diameter mirror, compared to Hubble’s 2.4 m (7.9 ft). This gives the Webb telescope a light collecting area about 6.25[21] times as large as Hubble’s: Webb’s collecting area is 25.37 square meters compared to Hubble’s 4.0.[21] Unlike Hubble, which observes in the near ultraviolet, visible, and near infrared (0.1–1.0 μm) spectra, JWST will observe in a lower frequency range, from long-wavelength visible light (red) through mid-infrared (0.6–28.3 μm). The telescope must be kept extremely cold, below 50 K (−223 °C; −370 °F), to observe faint signals in the infrared without interference from any other sources of warmth. It is deployed in a solar orbit near the Sun–Earth L2 Lagrange point, about 1.5 million kilometers (930,000 mi) from Earth, where its five layer kite-shaped sunshield protects it from warming by the Sun, Earth and Moon.[22][23]
Development began in 1996 for a launch that was initially planned for 2007 with a US$500 million budget.[24] There were many delays and cost overruns, including a major redesign in 2005,[25] a ripped sunshield during a practice deployment, a recommendation from an independent review board, a threat by the U.S. Congress to cancel the project, the COVID-19 pandemic,[26][27][28] problems with the Ariane 5 rocket[29] and the telescope itself, and communications glitches between the telescope and the launch vehicle.[30] The high-stakes nature of the launch and the telescope’s complexity were remarked upon by the media, and commented on by scientists and engineers.[31][32] Construction was completed in late 2016, followed by years of extensive testing.[33][34] The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development and the Space Telescope Science Institute in Baltimore operates JWST.[35] The prime contractor was Northrop Grumman.[36]
The telescope was released from the rocket upper stage 27 minutes after launch,[37] which NASA described as “flawless” and “perfect”.[38] As of 24 January 2022, the sunshield, mirrors and other components were fully unfolded to their operational configuration,[39][40] the spacecraft entered orbit at its destination,[41][42] and all instruments were successfully powered on.[43] On 3 February 2022, NASA tweeted that the telescope detected its first photons,[44] and on 11 February 2022, NASA announced the telescope had almost completed phase 1 of alignment, with every segment of its primary mirror having located, imaged, and approximately centered the target star HD 84406.[45][46] Phase 1 of the 7-phase alignment process was completed on February 18, 2022,[47] and phases 2 and 3 were completed a week later on February 25, 2022, meaning that the 18 primary segments now work in unison, but still act as 18 smaller telescopes rather than a single larger one.[48] Several weeks are still needed for the telescope to cool to its operational temperature. Mirror alignment and focusing and final testing and calibration will take about five months in total, potentially including the first formal images,[49][50] before planned research begins.[51][52]
