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132-480: The James Webb Space Telescope ( JWST ) is a space telescope designed to conduct infrared astronomy . As the largest telescope in space , it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, distant , or faint for the Hubble Space Telescope . This enables investigations across many fields of astronomy and cosmology , such as observation of

264-483: A dewar with an extremely cold substance, such as liquid helium . The coolant will slowly vaporize, limiting the lifetime of the instrument from as short as a few months to a few years at most. It is also possible to maintain a low temperature by designing the spacecraft to enable near-infrared observations without a supply of coolant, as with the extended missions of the Spitzer Space Telescope and

396-580: A spectral resolution of 90,000. Also optimized for ultraviolet observations were the FOC and FOS, which were capable of the highest spatial resolution of any instruments on Hubble. Rather than CCDs, these three instruments used photon -counting digicons as their detectors. The FOC was constructed by ESA, while the University of California, San Diego , and Martin Marietta Corporation built

528-400: A "new sky" for astronomers. However, there is a challenge involved in the design of infrared telescopes: they need to stay extremely cold, and the longer the wavelength of infrared, the colder they need to be. If not, the background heat of the device itself overwhelms the detectors, making it effectively blind. This can be overcome by careful design. One method is to put the key instruments in

660-471: A "sop" to the astronomy community. "There's something in there, so all is well". I figured in my own little head that to get that community energized we'd be better off zeroing it out. Then they would say, "Whoa, we're in deep trouble", and it would marshal the troops. So I advocated that we not put anything in. I don't remember any of the detailed discussions or whether there were any, but Jim went along with that so we zeroed it out. It had, from my perspective,

792-653: A 22-month launch delay (from 2011 to 2013), and elimination of system-level testing for observatory modes at wavelengths shorter than 1.7 μm. Other major features of the observatory were unchanged. Following the re-planning, the project was independently reviewed in April 2006. In the 2005 re-plan, the life-cycle cost of the project was estimated at US$ 4.5 billion. This comprised approximately US$ 3.5 billion for design, development, launch and commissioning, and approximately US$ 1.0 billion for ten years of operations. The ESA agreed in 2004 to contributing about €300 million, including

924-576: A 6.5-meter-diameter (21 ft) mirror, compared with Hubble's 2.4 m (7 ft 10 in). This gives Webb a light-collecting area of about 25 m (270 sq ft), about six times that of Hubble. Unlike Hubble, which observes in the near ultraviolet and visible (0.1 to 0.8  μm ), and near infrared (0.8–2.5 μm) spectra, Webb observes a lower frequency range, from long-wavelength visible light (red) through mid-infrared (0.6–28.5 μm). The telescope must be kept extremely cold, below 50 K (−223 °C; −370 °F), so that

1056-556: A NEXUS precursor telescope mission. Correcting the flawed optics of the Hubble Space Telescope (HST) in its first years played a significant role in the birth of Webb. In 1993, NASA conducted STS-61 , the Space Shuttle mission that replaced HST's camera and installed a retrofit for its imaging spectrograph to compensate for the spherical aberration in its primary mirror . The HST & Beyond Committee

1188-500: A costly program had a lengthy working life, and the concurrent development of plans for the reusable Space Shuttle indicated that the technology to allow this was soon to become available. The continuing success of the OAO program encouraged increasingly strong consensus within the astronomical community that the LST should be a major goal. In 1970, NASA established two committees, one to plan

1320-419: A different point from the light reflecting off its center. The effect of the mirror flaw on scientific observations depended on the particular observation—the core of the aberrated PSF was sharp enough to permit high-resolution observations of bright objects, and spectroscopy of point sources was affected only through a sensitivity loss. However, the loss of light to the large, out-of-focus halo severely reduced

1452-437: A final sharp focus and the best image quality obtained was drastically lower than expected. Images of point sources spread out over a radius of more than one arcsecond, instead of having a point spread function (PSF) concentrated within a circle 0.1  arcseconds (485 n rad ) in diameter, as had been specified in the design criteria. Analysis of the flawed images revealed that the primary mirror had been polished to

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1584-582: A mass of 350 kg (770 lb), and must support the 6,200 kg (13,700 lb) space telescope. It is made primarily of graphite composite material. The assembly was completed in California in 2015. It was integrated with the rest of the space telescope leading to its 2021 launch. The spacecraft bus can rotate the telescope with a pointing precision of one arcsecond , and isolates vibration to two milliarcseconds. Webb has two pairs of rocket engines (one pair for redundancy) to make course corrections on

1716-538: A nitrogen gas purge was performed before launching the telescope into space. As well as electrical power systems, the Pointing Control System controls HST orientation using five types of sensors (magnetic sensors, optical sensors, and six gyroscopes) and two types of actuators ( reaction wheels and magnetic torquers ). While construction of the spacecraft in which the telescope and instruments would be housed proceeded somewhat more smoothly than

1848-554: A possibly failure-prone battery, and make other improvements. Furthermore, the ground software needed to control Hubble was not ready in 1986, and was barely ready by the 1990 launch. Following the resumption of shuttle flights, Space Shuttle Discovery successfully launched the Hubble on April 24, 1990, as part of the STS-31 mission. At launch, NASA had spent approximately US$ 4.7 billion in inflation-adjusted 2010 dollars on

1980-648: A process called the Independent Comprehensive Review Panel, which led to a re-plan of the mission aiming for a 2015 launch, but as late as 2018. By 2010, cost over-runs were impacting other projects, though Webb itself remained on schedule. By 2011, the Webb project was in the final design and fabrication phase (Phase C). Assembly of the hexagonal segments of the primary mirror, which was done via robotic arm, began in November 2015 and

2112-460: A reflective coating of 65 nm-thick aluminum and a protective coating of 25 nm-thick magnesium fluoride . Doubts continued to be expressed about Perkin-Elmer's competence on a project of this importance, as their budget and timescale for producing the rest of the OTA continued to inflate. In response to a schedule described as "unsettled and changing daily", NASA postponed the launch date of

2244-518: A report emphasizing the need for a space telescope, and eventually, the Senate agreed to half the budget that had originally been approved by Congress. The funding issues led to a reduction in the scale of the project, with the proposed mirror diameter reduced from 3 m to 2.4 m, both to cut costs and to allow a more compact and effective configuration for the telescope hardware. A proposed precursor 1.5 m (4 ft 11 in) space telescope to test

2376-565: A resolution of 0.64 megapixels. The wide field camera (WFC) covered a large angular field at the expense of resolution, while the planetary camera (PC) took images at a longer effective focal length than the WF chips, giving it a greater magnification. The Goddard High Resolution Spectrograph (GHRS) was a spectrograph designed to operate in the ultraviolet. It was built by the Goddard Space Flight Center and could achieve

2508-508: A telescope could be propelled into Earth orbit by a rocket. The history of the Hubble Space Telescope can be traced to 1946, to astronomer Lyman Spitzer 's paper "Astronomical advantages of an extraterrestrial observatory". In it, he discussed the two main advantages that a space-based observatory would have over ground-based telescopes. First, the angular resolution (the smallest separation at which objects can be clearly distinguished) would be limited only by diffraction , rather than by

2640-507: A telescope in space. Spitzer's proposal called for a large telescope that would not be hindered by Earth's atmosphere. After lobbying in the 1960s and 70s for such a system to be built, Spitzer's vision ultimately materialized into the Hubble Space Telescope , which was launched on April 24, 1990, by the Space Shuttle Discovery (STS-31). This was launched due to many efforts by Nancy Grace Roman, "mother of Hubble", who

2772-538: A vital research tool and as a public relations boon for astronomy . The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories . The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a 2.4 m (7 ft 10 in) mirror, and its five main instruments observe in

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2904-478: A warm telescope, it is blinded by infrared emission from its own optical system. In addition to recommendations to extend the HST mission to 2005 and to develop technologies for finding planets around other stars, NASA embraced the chief recommendation of HST & Beyond for a large, cold space telescope (radiatively cooled far below 0 °C), and began the planning process for the future Webb telescope. Preparation for

3036-406: A way that is not accurately predictable. The density of the upper atmosphere varies according to many factors, and this means Hubble's predicted position for six weeks' time could be in error by up to 4,000 km (2,500 mi). Observation schedules are typically finalized only a few days in advance, as a longer lead time would mean there was a chance the target would be unobservable by the time it

3168-492: A wide field of view, with the disadvantage that the mirrors have shapes that are hard to fabricate and test. The mirror and optical systems of the telescope determine the final performance, and they were designed to exacting specifications. Optical telescopes typically have mirrors polished to an accuracy of about a tenth of the wavelength of visible light , but the Space Telescope was to be used for observations from

3300-415: A wide field. The secondary mirror is 0.74 m (2.4 ft) in diameter. In addition, there is a fine steering mirror which can adjust its position many times per second to provide image stabilization . Point light sources in images taken by Webb have six diffraction spikes plus two fainter ones, due to the hexagonal shape of the primary mirror segments. The Integrated Science Instrument Module (ISIM)

3432-508: Is a framework that provides electrical power, computing resources, cooling capability as well as structural stability to the Webb telescope. It is made with bonded graphite-epoxy composite attached to the underside of Webb's telescope structure. The ISIM holds the four science instruments and a guide camera. NIRCam and MIRI feature starlight-blocking coronagraphs for observation of faint targets such as extrasolar planets and circumstellar disks very close to bright stars. The spacecraft bus

3564-454: Is designed primarily for near-infrared astronomy , but can also see orange and red visible light, as well as the mid-infrared region, depending on the instrument being used. It can detect objects up to 100 times fainter than Hubble can, and objects much earlier in the history of the universe , back to redshift z≈20 (about 180 million years cosmic time after the Big Bang ). For comparison,

3696-414: Is designed to cool itself without a dewar, using a combination of sunshields and radiators, with the mid-infrared instrument using an additional cryocooler. Webb's delays and cost increases have been compared to those of its predecessor, the Hubble Space Telescope . When Hubble formally started in 1972, it had an estimated development cost of US$ 300 million (equivalent to $ 2,185,203,000 in 2023), but by

3828-533: Is limited by the filtering and distortion of electromagnetic radiation ( scintillation or twinkling) due to the atmosphere . A telescope orbiting Earth outside the atmosphere is subject neither to twinkling nor to light pollution from artificial light sources on Earth. As a result, the angular resolution of space telescopes is often much higher than a ground-based telescope with a similar aperture . Many larger terrestrial telescopes, however, reduce atmospheric effects with adaptive optics . Space-based astronomy

3960-504: Is more important for frequency ranges that are outside the optical window and the radio window , the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere. For example, X-ray astronomy is nearly impossible when done from Earth, and has reached its current importance in astronomy only due to orbiting X-ray telescopes such as the Chandra X-ray Observatory and

4092-419: Is obscured by the secondary support struts, giving a total collecting area of 25.4 m (273 sq ft). This is over six times larger than the collecting area of Hubble's 2.4 m (7.9 ft) diameter mirror, which has a collecting area of 4.0 m (43 sq ft). The mirror has a gold coating to provide infrared reflectivity and this is covered by a thin layer of glass for durability. Webb

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4224-511: Is opaque in many infrared bands (see figure at right). Even where the atmosphere is transparent, many of the target chemical compounds, such as water, carbon dioxide, and methane, also exist in the Earth's atmosphere, vastly complicating analysis. Existing space telescopes such as Hubble cannot study these bands since their mirrors are insufficiently cool (the Hubble mirror is maintained at about 15 °C [288 K; 59 °F]) which means that

4356-827: Is physically located in Baltimore , Maryland on the Homewood campus of Johns Hopkins University , one of the 39 U.S. universities and seven international affiliates that make up the AURA consortium. STScI was established in 1981 after something of a power struggle between NASA and the scientific community at large. NASA had wanted to keep this function in-house, but scientists wanted it to be based in an academic establishment. The Space Telescope European Coordinating Facility (ST-ECF), established at Garching bei München near Munich in 1984, provided similar support for European astronomers until 2011, when these activities were moved to

4488-525: Is the primary support component of the JWST, hosting a multitude of computing, communication, electric power, propulsion, and structural parts. Along with the sunshield, it forms the spacecraft element of the space telescope . The spacecraft bus is on the Sun-facing "warm" side of the sunshield and operates at a temperature of about 300 K (27 °C; 80 °F). The structure of the spacecraft bus has

4620-417: Is therefore composed of 18 hexagonal segments (a technique pioneered by Guido Horn d'Arturo ), which unfolded after the telescope was launched. Image plane wavefront sensing through phase retrieval is used to position the mirror segments in the correct location using precise actuators . Subsequent to this initial configuration, they only need occasional updates every few days to retain optimal focus. This

4752-582: Is unlike terrestrial telescopes, for example the Keck telescopes , which continually adjust their mirror segments using active optics to overcome the effects of gravitational and wind loading. The Webb telescope uses 132 small actuation motors to position and adjust the optics. The actuators can position the mirror with 10  nanometer accuracy. Webb's optical design is a three-mirror anastigmat , which makes use of curved secondary and tertiary mirrors to deliver images that are free from optical aberrations over

4884-585: The Challenger disaster brought the U.S. space program to a halt, grounded the Shuttle fleet, and forced the launch to be postponed for several years. During this delay the telescope was kept in a clean room, powered up and purged with nitrogen, until a launch could be rescheduled. This costly situation (about US$ 6 million per month) pushed the overall costs of the project higher. However, this delay allowed time for engineers to perform extensive tests, swap out

5016-592: The Columbia disaster (2003), but after NASA administrator Michael D. Griffin approved it, the servicing mission was completed in 2009. Hubble completed 30 years of operation in April 2020 and is predicted to last until 2030 to 2040. Hubble is the visible light telescope in NASA's Great Observatories program ; other parts of the spectrum are covered by the Compton Gamma Ray Observatory ,

5148-858: The Chandra X-ray Observatory , and the Spitzer Space Telescope (which covers the infrared bands). The mid-IR-to-visible band successor to the Hubble telescope is the James Webb Space Telescope (JWST), which was launched on December 25, 2021, with the Nancy Grace Roman Space Telescope due to follow in 2027. In 1923, Hermann Oberth —considered a father of modern rocketry, along with Robert H. Goddard and Konstantin Tsiolkovsky —published Die Rakete zu den Planetenräumen ("The Rocket into Planetary Space"), which mentioned how

5280-490: The ECMAScript standard and "allows for a modular design flow, where on-board scripts call lower-level scripts that are defined as functions". "The JWST science operations will be driven by ASCII (instead of binary command blocks) on-board scripts, written in a customized version of JavaScript. The script interpreter is run by the flight software, which is written in the programming language C++ . The flight software operates

5412-530: The Homewood Campus of Johns Hopkins University operates Webb. The primary contractor for the project was Northrop Grumman . The telescope is named after James E. Webb , who was the administrator of NASA from 1961 to 1968 during the Mercury , Gemini , and Apollo programs. Webb's primary mirror consists of 18 hexagonal mirror segments made of gold -plated beryllium , which together create

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5544-773: The Soviet space program (later succeeded by Roscosmos of Russia). As of 2022, many space observatories have already completed their missions, while others continue operating on extended time. However, the future availability of space telescopes and observatories depends on timely and sufficient funding. While future space observatories are planned by NASA, JAXA and the CNSA , scientists fear that there would be gaps in coverage that would not be covered immediately by future projects and this would affect research in fundamental science. On 16 January 2023, NASA announced preliminary considerations of several future space telescope programs, including

5676-570: The Wide-field Infrared Survey Explorer , which operated at reduced capacity after coolant depletion. Another example is Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument, which started out using a block of nitrogen ice that depleted after a couple of years, but was then replaced during the STS-109 servicing mission with a cryocooler that worked continuously. The Webb Space Telescope

5808-577: The XMM-Newton observatory . Infrared and ultraviolet are also largely blocked. Space telescopes are much more expensive to build than ground-based telescopes. Due to their location, space telescopes are also extremely difficult to maintain. The Hubble Space Telescope was serviced by the Space Shuttle , but most space telescopes cannot be serviced at all. Satellites have been launched and operated by NASA , ISRO , ESA , CNSA , JAXA and

5940-410: The atmosphere of Earth . Spitzer devoted much of his career to pushing for the development of a space telescope. In 1962, a report by the U.S. National Academy of Sciences recommended development of a space telescope as part of the space program , and in 1965, Spitzer was appointed as head of a committee given the task of defining scientific objectives for a large space telescope. Also crucial

6072-481: The earliest stars are thought to have formed between z≈30 and z≈20 (100–180 million years cosmic time), and the first galaxies may have formed around redshift z≈15 (about 270 million years cosmic time). Hubble is unable to see further back than very early reionization at about z≈11.1 (galaxy GN-z11 , 400 million years cosmic time). The design emphasizes the near to mid-infrared for several reasons: Ground-based telescopes must look through Earth's atmosphere , which

6204-401: The first stars and the formation of the first galaxies , and detailed atmospheric characterization of potentially habitable exoplanets . Although the Webb's mirror diameter is 2.7 times larger than that of the Hubble Space Telescope, it produces images of comparable sharpness because it observes in the longer-wavelength infrared spectrum. The longer the wavelength of the spectrum, the larger

6336-602: The infrared light emitted by the telescope itself does not interfere with the collected light. Its five-layer sunshield protects it from warming by the Sun, Earth, and Moon. Initial designs for the telescope, then named the Next Generation Space Telescope, began in 1996. Two concept studies were commissioned in 1999, for a potential launch in 2007 and a US$ 1 billion budget. The program was plagued with enormous cost overruns and delays. A major redesign

6468-407: The optical telescope assembly (OTA) and Fine Guidance Sensors for the space telescope. Lockheed was commissioned to construct and integrate the spacecraft in which the telescope would be housed. Optically, the HST is a Cassegrain reflector of Ritchey–Chrétien design , as are most large professional telescopes. This design, with two hyperbolic mirrors, is known for good imaging performance over

6600-468: The ultraviolet , visible , and near-infrared regions of the electromagnetic spectrum . Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detailed visible light images, allowing a deep view into space. Many Hubble observations have led to breakthroughs in astrophysics , such as determining

6732-465: The 1991 comedy The Naked Gun 2½: The Smell of Fear , in a scene where historical disasters are displayed, Hubble is pictured with RMS Titanic and LZ 129 Hindenburg . Nonetheless, during the first three years of the Hubble mission, before the optical corrections, the telescope carried out a large number of productive observations of less demanding targets. The error was well characterized and stable, enabling astronomers to partially compensate for

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6864-517: The 2000 Astronomy and Astrophysics Decadal Survey (a literature review produced by the United States National Research Council that includes identifying research priorities and making recommendations for the upcoming decade) included further development of the scientific program for what became known as the Next Generation Space Telescope, and advancements in relevant technologies by NASA. As it matured, studying

6996-568: The DF-224 was added during Servicing Mission 1 in 1993, which consisted of two redundant strings of an Intel-based 80386 processor with an 80387 math co-processor. The DF-224 and its 386 co-processor were replaced by a 25 MHz Intel-based 80486 processor system during Servicing Mission 3A in 1999. The new computer is 20 times faster, with six times more memory, than the DF-224 it replaced. It increases throughput by moving some computing tasks from

7128-462: The Earth, allowing the telescope to remain at a roughly constant distance with continuous orientation of its sunshield and equipment bus toward the Sun , Earth and Moon . Combined with its wide shadow-avoiding orbit, the telescope can simultaneously block incoming heat and light from all three of these bodies and avoid even the smallest changes of temperature from Earth and Moon shadows that would affect

7260-641: The European Space Astronomy Centre. One complex task that falls to STScI is scheduling observations for the telescope. Hubble is in a low-Earth orbit to enable servicing missions, which results in most astronomical targets being occulted by the Earth for slightly less than half of each orbit. Observations cannot take place when the telescope passes through the South Atlantic Anomaly due to elevated radiation levels, and there are also sizable exclusion zones around

7392-584: The FOS. The final instrument was the HSP, designed and built at the University of Wisconsin–Madison . It was optimized for visible and ultraviolet light observations of variable stars and other astronomical objects varying in brightness. It could take up to 100,000 measurements per second with a photometric accuracy of about 2% or better. HST's guidance system can also be used as a scientific instrument. Its three Fine Guidance Sensors (FGS) are primarily used to keep

7524-608: The Faint Object Spectrograph (FOS). WF/PC used a radial instrument bay, and the other four instruments were each installed in an axial instrument bay. WF/PC was a high-resolution imaging device primarily intended for optical observations. It was built by NASA's Jet Propulsion Laboratory , and incorporated a set of 48 filters isolating spectral lines of particular astrophysical interest. The instrument contained eight charge-coupled device (CCD) chips divided between two cameras, each using four CCDs. Each CCD has

7656-479: The Goddard Space Flight Center, Ball Aerospace & Technologies , and TRW to conduct technical requirement and cost studies of the three different concepts, and in 1999 selected Lockheed Martin and TRW for preliminary concept studies. Launch was at that time planned for 2007, but the launch date was pushed back many times (see table further down ). In 2002, the project was renamed after NASA's second administrator (1961–1968), James E. Webb (1906–1992). Webb led

7788-530: The Great Observatory Technology Maturation Program, Habitable Worlds Observatory , and New Great Observatories. Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble ) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope , but it is one of the largest and most versatile, renowned as

7920-624: The Mid Boom Assembly (MBA) which helps to deploy the large sunshields on orbit, while Ball Aerospace & Technologies was subcontracted to develop and build the OTE itself, and the Integrated Science Instrument Module (ISIM). Cost growth revealed in spring 2005 led to an August 2005 re-planning. The primary technical outcomes of the re-planning were significant changes in the integration and test plans,

8052-425: The Shuttle servicing missions. COSTAR was a corrective optics device rather than a science instrument, but occupied one of the four axial instrument bays. Since the final servicing mission in 2009, the four active instruments have been ACS, COS, STIS and WFC3. NICMOS is kept in hibernation, but may be revived if WFC3 were to fail in the future. Of the former instruments, three (COSTAR, FOS and WFPC2) are displayed in

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8184-725: The Smithsonian National Air and Space Museum . The FOC is in the Dornier museum, Germany. The HSP is in the Space Place at the University of Wisconsin–Madison . The first WFPC was dismantled, and some components were then re-used in WFC3. Within weeks of the launch of the telescope, the returned images indicated a serious problem with the optical system. Although the first images appeared to be sharper than those of ground-based telescopes, Hubble failed to achieve

8316-526: The Sun (precluding observations of Mercury ), Moon and Earth. The solar avoidance angle is about 50°, to keep sunlight from illuminating any part of the OTA. Earth and Moon avoidance keeps bright light out of the FGSs, and keeps scattered light from entering the instruments. If the FGSs are turned off, the Moon and Earth can be observed. Earth observations were used very early in the program to generate flat-fields for

8448-411: The Sun. Its actual position varies between about 250,000 and 832,000 km (155,000–517,000 mi) from L 2 as it orbits, keeping it out of both Earth and Moon's shadow. By way of comparison, Hubble orbits 550 km (340 mi) above Earth's surface, and the Moon is roughly 400,000 km (250,000 mi) from Earth. Objects near this Sun–Earth L 2 point can orbit the Sun in synchrony with

8580-566: The Sunshield review completed in January 2010. In April 2010, the telescope passed the technical portion of its Mission Critical Design Review (MCDR). Passing the MCDR signified the integrated observatory can meet all science and engineering requirements for its mission. The MCDR encompassed all previous design reviews. The project schedule underwent review during the months following the MCDR, in

8712-745: The WFPC1 instrument. There is a so-called continuous viewing zone (CVZ), within roughly 24° of Hubble's orbital poles , in which targets are not occulted for long periods. Due to the precession of the orbit, the location of the CVZ moves slowly over a period of eight weeks. Because the limb of the Earth is always within about 30° of regions within the CVZ, the brightness of scattered earthshine may be elevated for long periods during CVZ observations. Hubble orbits in low Earth orbit at an altitude of approximately 540 kilometers (340 mi) and an inclination of 28.5°. The position along its orbit changes over time in

8844-511: The agency during the Apollo program and established scientific research as a core NASA activity. In 2003, NASA awarded TRW the US$ 824.8 million prime contract for Webb. The design called for a de-scoped 6.1 m (20 ft) primary mirror and a launch date of 2010. Later that year, TRW was acquired by Northrop Grumman in a hostile bid and became Northrop Grumman Space Technology. Development

8976-564: The barrier of a single mirror. That meant going from "eliminate moving parts" to "learn to live with moving parts" (i.e. segmented optics). With the goal to reduce mass density tenfold, silicon carbide with a very thin layer of glass on top was first looked at, but beryllium was selected at the end. The mid-1990s era of "faster, better, cheaper" produced the NGST concept, with an 8 m (26 ft) aperture to be flown to L 2 , roughly estimated to cost US$ 500 million. In 1997, NASA worked with

9108-716: The beginning step in the process that ultimately moved the project into its detailed design phase (Phase C). By May 2007, costs were still on target. In March 2008, the project successfully completed its Preliminary Design Review (PDR). In April 2008, the project passed the Non-Advocate Review. Other passed reviews include the Integrated Science Instrument Module review in March 2009, the Optical Telescope Element review completed in October 2009, and

9240-428: The birth of galaxies in the young universe , and searching for planets around other stars – the prime goals coalesced as "Origins" by HST & Beyond became prominent. As hoped, the NGST received the highest ranking in the 2000 Decadal Survey. An administrator of NASA , Dan Goldin , coined the phrase " faster, better, cheaper ", and opted for the next big paradigm shift for astronomy, namely, breaking

9372-644: The construction of the OTA, Lockheed experienced some budget and schedule slippage, and by the summer 1985, construction of the spacecraft was 30% over budget and three months behind schedule. An MSFC report said Lockheed tended to rely on NASA directions rather than take their own initiative in the construction. The two initial, primary computers on the HST were the 1.25 MHz DF-224 system, built by Rockwell Autonetics, which contained three redundant CPUs, and two redundant NSSC-1 (NASA Standard Spacecraft Computer, Model 1) systems, developed by Westinghouse and GSFC using diode–transistor logic (DTL). A co-processor for

9504-498: The defective mirror by using sophisticated image processing techniques such as deconvolution . A commission headed by Lew Allen , director of the Jet Propulsion Laboratory , was established to determine how the error could have arisen. The Allen Commission found that a reflective null corrector , a testing device used to achieve a properly shaped non-spherical mirror, had been incorrectly assembled—one lens

9636-534: The delicate film structure during deployment testing in 2018 led to further delays to the telescope deployment. The sunshield was designed to be folded twelve times so that it would fit within the Ariane ;5 rocket's payload fairing , which is 4.57 m (15.0 ft) in diameter, and 16.19 m (53.1 ft) long. The shield's fully deployed dimensions were planned as 14.162 m × 21.197 m (46.46 ft × 69.54 ft). Keeping within

9768-496: The desired impact of stimulating the astronomy community to renew their efforts on the lobbying front. While I like to think in hindsight it was a brilliant political move, I'm not sure I thought it through all that well. It was something that was spur of the moment. [...] $ 5 million would let them think that all is well anyway, but it's not. So let's give them a message. My own thinking, get them stimulated to get into action. Zeroing it out would certainly give that message. I think it

9900-428: The engineering side of the space telescope project, and the other to determine the scientific goals of the mission. Once these had been established, the next hurdle for NASA was to obtain funding for the instrument, which would be far more costly than any Earth-based telescope. The U.S. Congress questioned many aspects of the proposed budget for the telescope and forced cuts in the budget for the planning stages, which at

10032-405: The go-ahead, work on the program was divided among many institutions. Marshall Space Flight Center (MSFC) was given responsibility for the design, development, and construction of the telescope, while Goddard Space Flight Center was given overall control of the scientific instruments and ground-control center for the mission. MSFC commissioned the optics company Perkin-Elmer to design and build

10164-435: The ground to the spacecraft and saves money by allowing the use of modern programming languages. Additionally, some of the science instruments and components had their own embedded microprocessor-based control systems. The MATs (Multiple Access Transponder) components, MAT-1 and MAT-2, use Hughes Aircraft CDP1802CD microprocessors. The Wide Field and Planetary Camera (WFPC) also used an RCA 1802 microprocessor (or possibly

10296-482: The important role space-based observations could play in astronomy. In 1968, NASA developed firm plans for a space-based reflecting telescope with a mirror 3 m (9.8 ft) in diameter, known provisionally as the Large Orbiting Telescope or Large Space Telescope (LST), with a launch slated for 1979. These plans emphasized the need for crewed maintenance missions to the telescope to ensure such

10428-566: The information-gathering surface required (mirrors in the infrared spectrum or antenna area in the millimeter and radio ranges) for an image comparable in clarity to the visible spectrum of the Hubble Space Telescope. The Webb was launched on 25 December 2021 on an Ariane 5 rocket from Kourou , French Guiana. In January 2022 it arrived at its destination, a solar orbit near the Sun–Earth L 2 Lagrange point , about 1.5 million kilometers (930,000 mi) from Earth. The telescope's first image

10560-467: The intended −1.00230 . The same number was also derived by analyzing the null corrector used by Perkin-Elmer to figure the mirror, as well as by analyzing interferograms obtained during ground testing of the mirror. Because of the way the HST's instruments were designed, two different sets of correctors were required. The design of the Wide Field and Planetary Camera 2, already planned to replace

10692-400: The launch by an additional 10 months to March 2021, based on the assessment of the independent review board convened after the failed March 2018 test deployment. The review identified that Webb launch and deployment had 344 potential single-point failures – tasks that had no alternative or means of recovery if unsuccessful, and therefore had to succeed for the telescope to work. In August 2019,

10824-608: The launch. The CSA pledged CA$ 39 million in 2007 and in 2012 delivered its contributions in equipment to point the telescope and detect atmospheric conditions on distant planets. In January 2007, nine of the ten technology development items in the project successfully passed a Non-Advocate Review. These technologies were deemed sufficiently mature to retire significant risks in the project. The remaining technology development item (the MIRI cryocooler) completed its technology maturation milestone in April 2007. This technology review represented

10956-626: The mechanical integration of the telescope was completed, something that was scheduled to be done 12 years before in 2007. After construction was completed, Webb underwent final tests at Northrop Grumman's historic Space Park in Redondo Beach, California. A ship carrying the telescope left California on 26 September 2021, passed through the Panama Canal , and arrived in French Guiana on 12 October 2021. NASA's lifetime cost for

11088-415: The mirror being ground very precisely but to the wrong shape. During fabrication, a few tests using conventional null correctors correctly reported spherical aberration . But these results were dismissed, thus missing the opportunity to catch the error, because the reflective null corrector was considered more accurate. The commission blamed the failings primarily on Perkin-Elmer. Relations between NASA and

11220-421: The mirror to the required shape. However, in case their cutting-edge technology ran into difficulties, NASA demanded that PE sub-contract to Kodak to construct a back-up mirror using traditional mirror-polishing techniques. (The team of Kodak and Itek also bid on the original mirror polishing work. Their bid called for the two companies to double-check each other's work, which would have almost certainly caught

11352-425: The mirror's weight to a minimum it consisted of top and bottom plates, each 25 mm (0.98 in) thick, sandwiching a honeycomb lattice. Perkin-Elmer simulated microgravity by supporting the mirror from the back with 130 rods that exerted varying amounts of force. This ensured the mirror's final shape would be correct and to specification when deployed. Mirror polishing continued until May 1981. NASA reports at

11484-427: The mirror. While the commission heavily criticized Perkin-Elmer for these managerial failings, NASA was also criticized for not picking up on the quality control shortcomings, such as relying totally on test results from a single instrument. Many feared that Hubble would be abandoned. The design of the telescope had always incorporated servicing missions, and astronomers immediately began to seek potential solutions to

11616-442: The near-IR and mid-IR sensitivity to be able to observe virtually all known Kuiper Belt Objects . In addition, it can observe opportunistic and unplanned targets within 48 hours of a decision to do so, such as supernovae and gamma ray bursts . Webb operates in a halo orbit , circling around a point in space known as the Sun–Earth L 2 Lagrange point , approximately 1,500,000 km (930,000 mi) beyond Earth's orbit around

11748-464: The observatory, as was done for Hubble, would not be possible, and according to NASA Associate Administrator Thomas Zurbuchen , despite best efforts, an uncrewed remote mission was found to be beyond available technology at the time Webb was designed. During the long Webb testing period, NASA officials referred to the idea of a servicing mission, but no plans were announced. Since the successful launch, NASA has stated that nevertheless limited accommodation

11880-429: The observing time on the telescope. Congress eventually approved funding of US$ 36 million for 1978, and the design of the LST began in earnest, aiming for a launch date of 1983. In 1983, the telescope was named after Edwin Hubble , who confirmed one of the greatest scientific discoveries of the 20th century, made by Georges Lemaître , that the universe is expanding . Once the Space Telescope project had been given

12012-666: The older 1801 version). The WFPC-1 was replaced by the WFPC-2 during Servicing Mission 1 in 1993, which was then replaced by the Wide Field Camera 3 (WFC3) during Servicing Mission 4 in 2009. The upgrade extended Hubble's capability of seeing deeper into the universe and providing images in three broad regions of the spectrum. When launched, the HST carried five scientific instruments: the Wide Field and Planetary Camera (WF/PC), Goddard High Resolution Spectrograph (GHRS), High Speed Photometer (HSP), Faint Object Camera (FOC) and

12144-411: The optics company had been severely strained during the telescope construction, due to frequent schedule slippage and cost overruns. NASA found that Perkin-Elmer did not review or supervise the mirror construction adequately, did not assign its best optical scientists to the project (as it had for the prototype), and in particular did not involve the optical designers in the construction and verification of

12276-607: The polishing error that later caused problems .) The Kodak mirror is now on permanent display at the National Air and Space Museum . An Itek mirror built as part of the effort is now used in the 2.4 m telescope at the Magdalena Ridge Observatory . Construction of the Perkin-Elmer mirror began in 1979, starting with a blank manufactured by Corning from their ultra-low expansion glass. To keep

12408-425: The problem that could be applied at the first servicing mission, scheduled for 1993. While Kodak had ground a back-up mirror for Hubble, it would have been impossible to replace the mirror in orbit, and too expensive and time-consuming to bring the telescope back to Earth for a refit. Instead, the fact that the mirror had been ground so precisely to the wrong shape led to the design of new optical components with exactly

12540-460: The project is expected to be US$ 9.7 billion, of which US$ 8.8 billion was spent on spacecraft design and development and US$ 861 million is planned to support five years of mission operations. Representatives from ESA and CSA stated their project contributions amount to approximately €700 million and CA$ 200 million, respectively. Space telescope In 1946, American theoretical astrophysicist Lyman Spitzer , "father of Hubble" proposed to put

12672-585: The project. Hubble's cumulative costs are estimated to be about US$ 11.3 billion in 2015 dollars, which include all subsequent servicing costs, but not ongoing operations, making it the most expensive science mission in NASA history. Hubble accommodates five science instruments at a given time, plus the Fine Guidance Sensors , which are mainly used for aiming the telescope but are occasionally used for scientific astrometry measurements. Early instruments were replaced with more advanced ones during

12804-654: The rate of expansion of the universe . Space telescopes were proposed as early as 1923, and the Hubble telescope was funded and built in the 1970s by the United States space agency NASA with contributions from the European Space Agency . Its intended launch was in 1983, but the project was beset by technical delays, budget problems, and the 1986 Challenger disaster . Hubble was finally launched in 1990, but its main mirror had been ground incorrectly, resulting in spherical aberration that compromised

12936-409: The same error but in the opposite sense, to be added to the telescope at the servicing mission, effectively acting as " spectacles " to correct the spherical aberration. The first step was a precise characterization of the error in the main mirror. Working backwards from images of point sources, astronomers determined that the conic constant of the mirror as built was −1.01390 ± 0.0002 , instead of

13068-428: The scientific community into fighting for full funding. As Hinners recalls: It was clear that year that we weren't going to be able to get a full-up start. There was some opposition on [Capitol] Hill to getting a new start on [Hubble]. It was driven, in large part as I recall, by the budget situation. Jim Fletcher proposed that we put in $ 5 million as a placeholder. I didn't like that idea. It was, in today's vernacular,

13200-484: The shadow of the sunshield limits the field of regard of Webb at any given time. The telescope can see 40 percent of the sky from any one position, but can see all of the sky over a period of six months. Webb's primary mirror is a 6.5 m (21 ft)-diameter gold-coated beryllium reflector with a collecting area of 25.4 m (273 sq ft). If it had been designed as a single, large mirror, it would have been too large for existing launch vehicles. The mirror

13332-566: The spacecraft and the science instruments." The desire for a large infrared space telescope traces back decades. In the United States, the Space Infrared Telescope Facility (later called the Spitzer Space Telescope ) was planned while the Space Shuttle was in development, and the potential for infrared astronomy was acknowledged at that time. Unlike ground telescopes, space observatories are free from atmospheric absorption of infrared light. Space observatories opened

13464-424: The structure, yet still maintain uninterrupted solar power and Earth communications on its sun-facing side. This arrangement keeps the temperature of the spacecraft constant and below the 50 K (−223 °C; −370 °F) necessary for faint infrared observations. To make observations in the infrared spectrum , Webb must be kept under 50 K (−223.2 °C; −369.7 °F); otherwise, infrared radiation from

13596-434: The structures on the dark side is critical to maintaining precise alignment of the primary mirror segments. The sunshield consists of five layers, each approximately as thin as a human hair. Each layer is made of Kapton E film, coated with aluminum on both sides. The two outermost layers have an additional coating of doped silicon on the Sun-facing sides, to better reflect the Sun's heat back into space. Accidental tears of

13728-494: The systems to be used on the main satellite was dropped, and budgetary concerns also prompted collaboration with the European Space Agency (ESA). ESA agreed to provide funding and supply one of the first generation instruments for the telescope, as well as the solar cells that would power it, and staff to work on the telescope in the United States, in return for European astronomers being guaranteed at least 15% of

13860-560: The telescope accurately pointed during an observation, but can also be used to carry out extremely accurate astrometry ; measurements accurate to within 0.0003 arcseconds have been achieved. The Space Telescope Science Institute (STScI) is responsible for the scientific operation of the telescope and the delivery of data products to astronomers. STScI is operated by the Association of Universities for Research in Astronomy (AURA) and

13992-458: The telescope and instruments sit. Within the shell, a graphite-epoxy frame keeps the working parts of the telescope firmly aligned. Because graphite composites are hygroscopic , there was a risk that water vapor absorbed by the truss while in Lockheed's clean room would later be expressed in the vacuum of space; resulting in the telescope's instruments being covered by ice. To reduce that risk,

14124-483: The telescope itself radiates strongly in the relevant infrared bands. Webb can also observe objects in the Solar System at an angle of more than 85° from the Sun and having an apparent angular rate of motion less than 0.03 arc seconds per second. This includes Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, their satellites , and comets , asteroids and minor planets at or beyond the orbit of Mars . Webb has

14256-433: The telescope itself would overwhelm its instruments. Its large sunshield blocks light and heat from the Sun, Earth, and Moon, and its position near the Sun–Earth L 2 keeps all three bodies on the same side of the spacecraft at all times. Its halo orbit around the L 2 point avoids the shadow of the Earth and Moon, maintaining a constant environment for the sunshield and solar arrays. The resulting stable temperature for

14388-400: The telescope until April 1985. Perkin-Elmer's schedules continued to slip at a rate of about one month per quarter, and at times delays reached one day for each day of work. NASA was forced to postpone the launch date until March and then September 1986. By this time, the total project budget had risen to US$ 1.175 billion. The spacecraft in which the telescope and instruments were to be housed

14520-403: The telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the only telescope designed to be maintained in space by astronauts. Five Space Shuttle missions have repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments. The fifth mission was initially canceled on safety grounds following

14652-623: The telescope. Her work as project scientist helped set the standards for NASA's operation of large scientific projects. Space-based astronomy had begun on a very small scale following World War II , as scientists made use of developments that had taken place in rocket technology. The first ultraviolet spectrum of the Sun was obtained in 1946, and NASA launched the Orbiting Solar Observatory (OSO) to obtain UV, X-ray, and gamma-ray spectra in 1962. An orbiting solar telescope

14784-449: The time consisted of very detailed studies of potential instruments and hardware for the telescope. In 1974, public spending cuts led to Congress deleting all funding for the telescope project. In 1977, then NASA Administrator James C. Fletcher proposed a token $ 5 million for Hubble in NASA's budget. Then NASA Associate Administrator for Space Science, Noel Hinners , instead cut all funding for Hubble, gambling that this would galvanize

14916-639: The time it was sent into orbit in 1990, the cost was about four times that. In addition, new instruments and servicing missions increased the cost to at least US$ 9 billion by 2006 (equivalent to $ 13,602,509,000 in 2023). Discussions of a Hubble follow-on started in the 1980s, but serious planning began in the early 1990s. The Hi-Z telescope concept was developed between 1989 and 1994: a fully baffled 4 m (13 ft) aperture infrared telescope that would recede to an orbit at 3 Astronomical unit (AU). This distant orbit would have benefited from reduced light noise from zodiacal dust . Other early plans called for

15048-408: The time questioned Perkin-Elmer's managerial structure, and the polishing began to slip behind schedule and over budget. To save money, NASA halted work on the back-up mirror and moved the launch date of the telescope to October 1984. The mirror was completed by the end of 1981; it was washed using 9,100 L (2,000 imp gal; 2,400 US gal) of hot, deionized water and then received

15180-464: The turbulence in the atmosphere, which causes stars to twinkle, known to astronomers as seeing . At that time ground-based telescopes were limited to resolutions of 0.5–1.0 arcseconds , compared to a theoretical diffraction-limited resolution of about 0.05 arcsec for an optical telescope with a mirror 2.5 m (8 ft 2 in) in diameter. Second, a space-based telescope could observe infrared and ultraviolet light, which are strongly absorbed by

15312-409: The usefulness of the telescope for faint objects or high-contrast imaging. This meant nearly all the cosmological programs were essentially impossible, since they required observation of exceptionally faint objects. This led politicians to question NASA's competence, scientists to rue the cost which could have gone to more productive endeavors, and comedians to make jokes about NASA and the telescope. In

15444-656: The visible through the ultraviolet (shorter wavelengths) and was specified to be diffraction limited to take full advantage of the space environment. Therefore, its mirror needed to be polished to an accuracy of 10 nanometers, or about 1/65 of the wavelength of red light. On the long wavelength end, the OTA was not designed with optimum infrared performance in mind—for example, the mirrors are kept at stable (and warm, about 15 °C) temperatures by heaters. This limits Hubble's performance as an infrared telescope. Perkin-Elmer (PE) intended to use custom-built and extremely sophisticated computer-controlled polishing machines to grind

15576-471: The way to L 2 and for station keeping  – maintaining the correct position in the halo orbit. Eight smaller thrusters are used for attitude control  – the correct pointing of the spacecraft. The engines use hydrazine fuel (159 liters or 42 U.S. gallons at launch) and dinitrogen tetroxide as oxidizer (79.5 liters or 21.0 U.S. gallons at launch). Webb is not intended to be serviced in space. A crewed mission to repair or upgrade

15708-406: The wrong shape. Although it was believed to be one of the most precisely figured optical mirrors ever made, smooth to about 10 nanometers, the outer perimeter was too flat by about 2200 nanometers (about 1 ⁄ 450 mm or 1 ⁄ 11000 inch). This difference was catastrophic, introducing severe spherical aberration, a flaw in which light reflecting off the edge of a mirror focuses on

15840-561: Was accomplished in 2005, with construction completed in 2016, followed by years of exhaustive testing, at a total cost of US$ 10 billion. The mass of the James Webb Space Telescope (JWST) is about half that of the Hubble Space Telescope . Webb has a 6.5 m (21 ft)-diameter gold -coated beryllium primary mirror made up of 18 separate hexagonal mirrors. The mirror has a polished area of 26.3 m (283 sq ft), of which 0.9 m (9.7 sq ft)

15972-407: Was another major engineering challenge. It would have to withstand frequent passages from direct sunlight into the darkness of Earth's shadow , which would cause major changes in temperature, while being stable enough to allow extremely accurate pointing of the telescope. A shroud of multi-layer insulation keeps the temperature within the telescope stable and surrounds a light aluminum shell in which

16104-466: Was as simple as that. Didn't talk to anybody else about doing it first, just, "Let's go do that". Voila, it worked. Don't know whether I'd do that again. The political ploy worked. In response to Hubble being zeroed out of NASA's budget, a nationwide lobbying effort was coordinated among astronomers. Many astronomers met congressmen and senators in person, and large-scale letter-writing campaigns were organized. The National Academy of Sciences published

16236-438: Was completed on 3 February 2016. The secondary mirror was installed on 3 March 2016. Final construction of the Webb telescope was completed in November 2016, after which extensive testing procedures began. In March 2018, NASA delayed Webb's launch an additional two years to May 2020 after the telescope's sunshield ripped during a practice deployment and the sunshield's cables did not sufficiently tighten. In June 2018, NASA delayed

16368-534: Was due to be observed. Engineering support for HST is provided by NASA and contractor personnel at the Goddard Space Flight Center in Greenbelt, Maryland , 48 km (30 mi) south of the STScI. Hubble's operation is monitored 24 hours per day by four teams of flight controllers who make up Hubble's Flight Operations Team. By January 1986, the planned launch date for Hubble that October looked feasible, but

16500-419: Was formed in 1994 "to study possible missions and programs for optical-ultraviolet astronomy in space for the first decades of the 21st century." Emboldened by HST's success, its 1996 report explored the concept of a larger and much colder, infrared-sensitive telescope that could reach back in cosmic time to the birth of the first galaxies. This high-priority science goal was beyond the HST's capability because, as

16632-613: Was launched in 1962 by the United Kingdom as part of the Ariel programme , and in 1966 NASA launched the first Orbiting Astronomical Observatory (OAO) mission. OAO-1's battery failed after three days, terminating the mission. It was followed by Orbiting Astronomical Observatory 2 (OAO-2), which carried out ultraviolet observations of stars and galaxies from its launch in 1968 until 1972, well beyond its original planned lifetime of one year. The OSO and OAO missions demonstrated

16764-440: Was made to facilitate future servicing missions. These accommodations included precise guidance markers in the form of crosses on the surface of Webb, for use by remote servicing missions, as well as refillable fuel tanks, removable heat protectors, and accessible attachment points. Ilana Dashevsky and Vicki Balzano write that Webb uses a modified version of JavaScript , called Nombas ScriptEase 5.00e, for its operations; it follows

16896-458: Was managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, with John C. Mather as its project scientist. The primary contractor was Northrop Grumman Aerospace Systems, responsible for developing and building the spacecraft element, which included the satellite bus , sunshield, Deployable Tower Assembly (DTA) which connects the Optical Telescope Element to the spacecraft bus, and

17028-414: Was out of position by 1.3 mm (0.051 in). During the initial grinding and polishing of the mirror, Perkin-Elmer analyzed its surface with two conventional refractive null correctors. However, for the final manufacturing step ( figuring ), they switched to the custom-built reflective null corrector, designed explicitly to meet very strict tolerances. The incorrect assembly of this device resulted in

17160-617: Was released to the public on 11 July 2022. The U.S. National Aeronautics and Space Administration (NASA) led Webb's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center in Maryland managed telescope development, while the Space Telescope Science Institute in Baltimore on

17292-630: Was the first Chief of Astronomy and first female executive at NASA. She was a program scientist that worked to convince NASA, Congress, and others that Hubble was "very well worth doing". The first operational space telescopes were the American Orbiting Astronomical Observatory , OAO-2 launched in 1968, and the Soviet Orion 1 ultraviolet telescope aboard space station Salyut 1 in 1971. Performing astronomy from ground-based observatories on Earth

17424-424: Was the work of Nancy Grace Roman , the "Mother of Hubble". Well before it became an official NASA project, she gave public lectures touting the scientific value of the telescope. After it was approved, she became the program scientist, setting up the steering committee in charge of making astronomer needs feasible to implement and writing testimony to Congress throughout the 1970s to advocate continued funding of

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