The James Webb Space Telescope Mission

In this section we present a brief timeline history of the concept, design, construction and testing of JWST.

II.1 1980s

In the 1980s, preliminary work by Garth Illingworth, Pierre Bély, Peter Stockman, and others on an 8m to 10m passively-cooled infrared telescope began at Space Telescope Science Institute (STScI), following Riccardo Giacconi’s advice to work on the “next big thing.” Progress was reported at the STScI/NASA Next Generation Space Telescope (NGST) conference, 1989 September 13 to 15. This international conference excited scientists and engineers with the scientific opportunities and technical challenges enabled by a very large cold infrared space telescope. A decade before that, in 1979, a National Academy of Sciences (NAS) report recommended the Shuttle Infrared Telescope Facility [37, SIRTF, later Spitzer;], even before the IRAS launch (1983 January 25). Goddard built the Cosmic Background Explorer (COBE) and launched it on 1989 November 18 to measure the Big Bang, the cosmic microwave and IR background light, beginning the era of precision cosmology. The discovery of the primeval anisotropy led to the standard model of cosmology, in which gravity acting on density fluctuations could produce galaxies. To build the COBE, Goddard also developed expertise with cryogenic instrumentation and test programs that would become essential for Webb.

II.2 1990s

The Hubble was launched 1990 April 24 and its optical error was soon discovered, leading to two breakthroughs: learning to measure the optical error (spherical aberration) with phase diversity, and demonstrating the value of the planned servicing and repair of Hubble using the Space Shuttle in 1993. The development of the phase diversity algorithms was jointly done by STScI, Goddard and JPL. The experience gained by the people working on the servicing missions, instrument upgrades, and spacecraft hardware repairs and replacements would be critically important for the development of the JWST, as many of the younger engineers working on Hubble later became leaders of the Webb team. The Bahcall report [3, Decadal Survey:] endorsed Spitzer (at that time called the Space Infrared Telescope Facility, SIRTF) and declared that the 1990s would be the “Decade of the Infrared.” The AstroTech conference reviewed possibilities for large telescopes and cited the Bahcall report. In 1993, the Edison mission, a deployable 2m+ diameter IR telescope, was proposed to ESA. Larger format IR detector arrays, in part spurred by the NICMOS development, enabled galaxy surveys [43, e.g.,] and other near-IR science with ground-based telescopes.

The Edison concept included passive cooling, and some of the people working on Edison brought that experience to the JWST team later. The Hubble phase retrieval algorithm was published and the Hubble optics were corrected in its first servicing mission. Soon after, NASA commissioned AURA’s HST and Beyond committee, chaired by Alan Dressler, to write a report on potential successors to HST. STScI sent a proposal entitled “High-Z” to NASA, suggesting that a telescope in a 1×3 AU long elliptical orbit would be helpful, to get outside the interference of the zodiacal dust cloud. In 1995, JPL submitted the MIRORS proposal to NASA for a passively cooled mid IR telescope.

II.2.1 1995

On 1995 October 30, Ed Weiler of NASA HQ left a phone message for John Mather at Goddard, explaining that NASA was starting a study of what was then called the Next Generation Space Telescope (NGST), and inviting his participation. Within the context of the previous studies, and based on a draft of the HST and Beyond report, NGST would be a 4m passively-cooled IR telescope making observations at 1μm<λ<5μm. GSFC chose Bernie Seery to manage the study. The Federal Government shut down 1995 November 14 to 19 and again 1995 December 16 to 1996 January 6. On 1996 January 6 to 8, a record blizzard closed the Washington DC area and nothing moved for a week. As a result Mather did not attend the dramatic AAS meeting in San Antonio. This pivotal start foreshadowed Webb’s future, as its development was to be affected by more storms, government shutdowns, a terrorist attack, an earthquake in Virginia, a lightning strike, a hurricane in Texas, and the COVID pandemic, all of which would occur before Webb was launched.

On 1996 January 15, the Hubble Deep Field image was released at the AAS meeting, completely changing our view of galaxies in the universe. On 1996 January 17, Dan Goldin spoke to the AAS, saying, “Why do you ask for such a modest thing [4m]? Why not go after six or seven meters?” He received a standing ovation, which turned out to be Webb’s first (informal) peer review. Dressler also spoke to present the report at the meeting. On 1996 January 22 to 25, Mather attended a conference in Johannesburg, and met ESA counterparts for the first time to discuss ideas for the NGST. The final Dressler report appeared in 1996 May. Wendy Freedman’s Hubble Key Project reported on the Hubble Constant, discussing their initial values (around 60kms⁻¹Mpc⁻¹) and comparing to others (up to 80kms⁻¹Mpc⁻¹) [41, and references therein]. Predictions of early galaxies that could be visible to Webb depend strongly on this number, and would be important when a descope decision was taken in 2001.

II.2.2 1996 to 1999

The year 1996 marked the industrial kickoff. Around May, GSFC presented NGST ideas to interested aerospace companies in a meeting held at the Space Telescope Science Institute (STScI). NASA issued a Cooperative Agreement Notice so the companies could compete for this new work. Two studies were chosen (TRW and Ball) and they and the Government/STScI teams reported in September. Jonathan Gardner, newly hired at Goddard, attended the meeting, learning about NGST for the first time. The reports said they could meet Goldin’s cost target of $0.5B, though what exactly was included in these estimates is unclear now. Outside this group, hardly anyone believed that such a low cost was possible.

In 1997, NASA solicited proposals for the Ad Hoc Science Working Group to advise NASA on the choice of scientific objectives and instruments; the committee first met later that year. In 1997, AURA issued a report “Visiting a Time When Galaxies were Young”, detailing the concepts that had been developed in 1996. In 1998, a conference in Liège, Belgium reported progress developing science drivers and technological challenges, after ESA established an NGST Task Force. The STScI was officially made the NGST Science Operations Center in a ceremony with Senator Barbara Mikulski and Administrator Goldin. The cosmic acceleration (dark energy) was discovered, adding to the growing sense that NGST was key to studies of the distant universe, as a dark-energy-dominated universe has galaxies forming at higher redshift than in a matter-dominated flat universe. The conference “Science with the NGST (Next Generation Space Telescope)” was held at GSFC.

On July 7, NASA selected Lockheed Martin and TRW to conduct Phase A mission studies, preliminary analysis of the design, and cost. Discussions began with international partners about their possible roles as ESA, CSA and the Japanese Space Agency (JAXA) participated in the ASWG. In September, just as hurricane Floyd approached, the NGST Science and Technology Exposition was held in Hyannis, MA and the choices of possible near IR spectrometer designs were presented. reported the early history of NGST and listed the instrument studies then underway. The MEMS (micro-electromechanical system) concept for a multi-object spectrometer was favored over a Fourier spectrometer, because the Fourier multiplex advantage does not apply if most of the sky is empty and detector noise is not high. described the microshutter array, which has significant advantages in size, contrast and cryogenic operation over the micromirror arrays developed by Texas Instruments for digital light projection.

The ASWG final report recommended that NGST include a NIRCam, NIRSpec with a MEMS-based multi-object spectrograph capability and a MIRI doing both imaging and spectroscopy. They gave three options for a fourth instrument: a tunable filter, a visible-light camera and an integral-field spectrograph. By this time, JAXA had decided not to participate in the mission, and the ASWG recommended that NASA partner with ESA and CSA.