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102-449: The Hubble Space Telescope has three fine guidance sensors (FGSs). Two are used to point and lock the telescope onto the target, and the third can be used for position measurements – also known as astrometry . Because the FGSs are so accurate, they can be used to measure stellar distances and also to investigate binary star systems. The three FGSs are located at 90-degree intervals around

204-580: 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

306-471: 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,

408-500: 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

510-419: 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

612-437: 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

714-625: A group of ten associate editors from Europe and the United States, established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics . It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of

816-508: A guide to understanding of other stars. The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the Hertzsprung–Russell diagram , which can be viewed as representing the state of a stellar object, from birth to destruction. Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate

918-463: A millisecond timescale ( millisecond pulsars ) or combine years of data ( pulsar deceleration studies). The information obtained from these different timescales is very different. The study of the Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Understanding the Sun serves as

1020-561: A model or help in choosing between several alternate or conflicting models. Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model. Topics studied by theoretical astrophysicists include stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in

1122-538: 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

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1224-554: 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

1326-460: 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

1428-518: 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

1530-565: 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

1632-542: A substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine the properties of dark matter , dark energy , black holes , and other celestial bodies ; and the origin and ultimate fate of the universe . Topics also studied by theoretical astrophysicists include Solar System formation and evolution ; stellar dynamics and evolution ; galaxy formation and evolution ; magnetohydrodynamics ; large-scale structure of matter in

1734-583: 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

1836-406: 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

1938-492: 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

2040-419: Is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler , said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space– what they are, rather than where they are", which is studied in celestial mechanics . Among

2142-635: Is mainly concerned with finding out the measurable implications of physical models . It is the practice of observing celestial objects by using telescopes and other astronomical apparatus. Most astrophysical observations are made using the electromagnetic spectrum . Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study

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2244-508: 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 the ultraviolet , visible , and near-infrared regions of

2346-827: 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

2448-585: 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

2550-644: 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 ,

2652-936: 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

2754-516: The Lambda-CDM model , are the Big Bang , cosmic inflation , dark matter, dark energy and fundamental theories of physics. The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms. There were scientists who were qualified in both physics and astronomy who laid the firm foundation for

2856-410: 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

2958-407: 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

3060-456: 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

3162-408: The 17th century, natural philosophers such as Galileo , Descartes , and Newton began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws . Their challenge was that the tools had not yet been invented with which to prove these assertions. For much of the nineteenth century, astronomical research was focused on

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3264-465: 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

3366-568: 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

3468-641: 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

3570-584: 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

3672-608: 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

3774-425: 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

3876-725: 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

3978-475: 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

4080-477: The Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories. Around 1920, following the discovery of the Hertzsprung–Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars , in his paper The Internal Constitution of the Stars . At that time,

4182-430: The Sun. Cosmic rays consisting of very high-energy particles can be observed hitting the Earth's atmosphere. Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia . On the other hand, radio observations may look at events on

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4284-745: 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

4386-596: The angular diameter of stars, galaxies, etc. Due to the sensitivity of the FGS they can not be used whilst the HST is pointed within 50 degrees of the Sun. A guiding system, also called FGS, but using different technology is used for the James Webb Space Telescope (JWST). It provides input for the observatory's attitude control system (ACS). During on-orbit commissioning of the JWST, the FGS also provided pointing error signals during activities to achieve alignment and phasing of

4488-494: The behaviors of a star) and computational numerical simulations . Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen. Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute

4590-446: The circumference of the telescope's field of view. To achieve the very high pointing accuracy Hubble needs, the FGSs have been constructed as interferometers to exploit the wavelike features of the in-coming starlight. With this kind of accuracy and precision, the sensors can search for a wobble in the motion of nearby stars that could indicate the presence of a planetary companion, determine if certain stars really are double stars, measure

4692-644: 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

4794-510: The current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss , Subrahmanyan Chandrasekhar , Stephen Hawking , Hubert Reeves , Carl Sagan and Patrick Moore . The efforts of the early, late, and present scientists continue to attract young people to study

4896-498: 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

4998-496: 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

5100-443: The end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths. In the 21st century, it further expanded to include observations based on gravitational waves . Observational astronomy is a division of the astronomical science that is concerned with recording and interpreting data, in contrast with theoretical astrophysics , which

5202-428: 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

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5304-428: The existing WF/PC, included relay mirrors to direct light onto the four separate charge-coupled device (CCD) chips making up its two cameras. An inverse error built into their surfaces could completely cancel the aberration of the primary. However, the other instruments lacked any intermediate surfaces that could be configured in this way, and so required an external correction device. Astrophysics Astrophysics

5406-405: 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

5508-435: 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

5610-482: 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

5712-467: 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

5814-415: 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

5916-421: 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

6018-425: 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

6120-427: 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

6222-419: The observed brightness and position of sources with the properties of catalogued objects selected by the observation planning software. The second is to acquire pre-selected guide stars. During acquisition, a guide star is first centred in an 8 × 8 pixel window. Small angle maneuvers are then executed to translate this window to a pre-specified location within the field of view , so that an observation with one of

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6324-429: 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

6426-666: 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

6528-411: 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

6630-455: The physicist, Gustav Kirchhoff , and the chemist, Robert Bunsen , had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements . Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere. In this way it

6732-607: 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

6834-425: 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

6936-585: 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

7038-591: 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

7140-405: The routine work of measuring the positions and computing the motions of astronomical objects. A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum . By 1860

7242-409: 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

7344-584: The science instruments will be oriented correctly. The third function is to provide the ACS with centroid measurements of the guide stars at a rate of 16 times per second. These measurements will be used to enable stable pointing at the milliarcsecond level. The FGS will be sensitive enough to reach 58 μ Jy at 1.25 μm (~Jab = 19.5), and has a 2.4×2.4 arcminute square field of view. This combination of sky coverage and sensitivity ensures that an appropriate guide star can be found with 95% probability at any point in

7446-428: 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,

7548-639: The segments of the deployable primary mirror. The JWST FGS, designed and built by COM DEV International , was supplied by the Canadian Space Agency . To save on mass and volume it was assembled into a single unit together with the Near Infrared Imager and Slitless Spectrograph, but they are separate optical instruments. The JWST FGS-Guider has three main functions. The first is to obtain images for target acquisition. Full-frame images are used to identify star fields by correlating

7650-442: The sky, including high galactic latitudes. 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 a vital research tool and as a public relations boon for astronomy . The Hubble telescope

7752-487: The solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium , after the Greek Helios , the Sun personified. In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory , in which a team of woman computers , notably Williamina Fleming , Antonia Maury , and Annie Jump Cannon , classified

7854-627: The source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein's equation E = mc . This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity ), had not yet been discovered. In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin ) wrote an influential doctoral dissertation at Radcliffe College , in which she applied Saha's ionization theory to stellar atmospheres to relate

7956-516: The spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering's vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922. In 1895, George Ellery Hale and James E. Keeler , along with

8058-408: The spectral classes to the temperature of stars. Most significantly, she discovered that hydrogen and helium were the principal components of stars, not the composition of Earth. Despite Eddington's suggestion, discovery was so unexpected that her dissertation readers (including Russell ) convinced her to modify the conclusion before publication. However, later research confirmed her discovery. By

8160-800: The subjects studied are the Sun ( solar physics ), other stars , galaxies , extrasolar planets , the interstellar medium and the cosmic microwave background . Emissions from these objects are examined across all parts of the electromagnetic spectrum , and the properties examined include luminosity , density , temperature , and chemical composition. Because astrophysics is a very broad subject, astrophysicists apply concepts and methods from many disciplines of physics, including classical mechanics , electromagnetism , statistical mechanics , thermodynamics , quantum mechanics , relativity , nuclear and particle physics , and atomic and molecular physics . In practice, modern astronomical research often involves

8262-494: 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

8364-560: 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

8466-458: 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,

8568-400: 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

8670-403: 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

8772-623: 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

8874-449: 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

8976-408: 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

9078-464: 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

9180-499: The universe; origin of cosmic rays ; general relativity , special relativity , quantum and physical cosmology (the physical study of the largest-scale structures of the universe), including string cosmology and astroparticle physics . Astronomy is an ancient science, long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion

9282-489: The universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Relativistic astrophysics serves as a tool to gauge the properties of large-scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole ( astro )physics and the study of gravitational waves . Some widely accepted and studied theories and models in astrophysics, now included in

9384-409: 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

9486-656: 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

9588-406: 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

9690-407: 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

9792-466: 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

9894-534: 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

9996-613: 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

10098-414: 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

10200-406: Was proved that the chemical elements found in the Sun and stars were also found on Earth. Among those who extended the study of solar and stellar spectra was Norman Lockyer , who in 1868 detected radiant, as well as dark lines in solar spectra. Working with chemist Edward Frankland to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in

10302-424: 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

10404-448: Was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal . Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato , or Aether as maintained by Aristotle . During

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