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James Webb Space Telescope

James Webb Space Telescope

Overview
The James Webb Space Telescope (JWST), previously known as Next Generation Space Telescope (NGST), is a planned next-generation space telescope, optimized for observations in the infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth, orbiting the Earth-Sun point, and four specialized instruments. The combination of these features will give JWST unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, enabling its two main scientific goals — studying the birth and evolution of galaxies, and the formation of stars and planets.

Formally planned since around 1996, JWST is a formal successor to the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 and the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...

.
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Encyclopedia
The James Webb Space Telescope (JWST), previously known as Next Generation Space Telescope (NGST), is a planned next-generation space telescope, optimized for observations in the infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth, orbiting the Earth-Sun point, and four specialized instruments. The combination of these features will give JWST unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, enabling its two main scientific goals — studying the birth and evolution of galaxies, and the formation of stars and planets.

Formally planned since around 1996, JWST is a formal successor to the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 and the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...

. The telescope is an international collaboration of about 17 countries led by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

, and with significant contributions from the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

, and the Canadian Space Agency. It is named after James E. Webb
James E. Webb
James Edwin Webb was an American government official who served as the second administrator of NASA from February 14, 1961 to October 7, 1968....

, the second administrator of NASA.

JWST's capabilities will enable a broad range of investigations across many subfields of astronomy. One particular goal involves observing some of the most distant objects in the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

, beyond the reach of current ground and space based instruments. This includes the very first stars, the epoch of reionization
Reionization
In Big Bang cosmology, reionization is the process that reionized the matter in the universe after the "dark ages," and is the second of two major phase changes of gas in the universe. As the majority of baryonic matter is in the form of hydrogen, reionization usually refers to the reionization of...

, and the formation of the first galaxies. Another goal is understanding the formation of stars and planets. This will include imaging molecular clouds and star-forming clusters, studying the debris disks around stars, direct imaging of planets, and spectroscopic examination of planetary transits.

The mission was under review for cancellation by the United States Congress. At that time, about 3 billion USD had been spent, and more than 75 percent of its hardware is either in production or undergoing testing. In November 2011, congress reversed plans to cancel the JWST and instead capped additional funding to complete the project at $8 billion.

Overview


It originated as the Next Generation Space Telescope (NGST) in 1996, based on generic planning for Hubble successor at least as early as 1993. It was renamed in 2002 after NASA's second administrator (1961–1968) James E. Webb
James E. Webb
James Edwin Webb was an American government official who served as the second administrator of NASA from February 14, 1961 to October 7, 1968....

 (1906–1992), noted for playing a role in the Apollo program and establishing scientific research as a core NASA activity.

The telescope is a project of the National Aeronautics and Space Administration, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 space agency, with international collaboration from the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 and the Canadian Space Agency, including contributions from fifteen nations.

Europe's contributions were formalized in 2007 with a ESA-NASA Memorandum of Understanding, that includes the Ariane-5 ECA launcher, NIRSpec instrument, MIRI Optical Bench Assembly, and manpower support for operations.

The JWST will orbit the Sun approximately 1500000 kilometres (932,059.1 mi) beyond the Earth, at the L2 Lagrange point (L2 halo orbit). Objects at the L2 point orbit the Sun in synchrony with the Earth, which allows the JWST to use one radiation shield, positioned between the telescope and the Sun, to protect it from the Sun's heat and light and a small amount of additional infrared from the Earth. The telescope will be in a very large 800000 kilometres (497,098.2 mi) radius halo orbit
Halo orbit
A halo orbit is a periodic, three-dimensional orbit near the , , or Lagrange points in the three-body problem of orbital mechanics. A spacecraft in a halo orbit does not technically orbit the Lagrange point itself , but travels in a closed, repeating path near the Lagrange point...

 around L2, and so will avoid any part of Earth's shadow.The Earth does not fully block the solar disc at the distance of the Earth-Sun , which is just outside of the Earth's umbra, but JWST avoids even the penumbra From the JWST's position, the Earth will be very close to the Sun's position but not eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...

 it, while the Moon will show a tiny crescent phase during its maximum angular distance from the Sun.

The telescope plans a launch on an Ariane 5
Ariane 5
Ariane 5 is, as a part of Ariane rocket family, an expendable launch system used to deliver payloads into geostationary transfer orbit or low Earth orbit . Ariane 5 rockets are manufactured under the authority of the European Space Agency and the Centre National d'Etudes Spatiales...

 rocket on a five-year mission (10-year goal) with a planned launch date in 2018.

Comparisons


Compared to other future observatories, most have already been canceled or put on hold including Terrestrial Planet Finder
Terrestrial Planet Finder
The Terrestrial Planet Finder was a proposed project by NASA to construct a system of telescopes for detecting extrasolar terrestrial planets. TPF was postponed several times and finally cancelled...

 (2011), Space Interferometry Mission
Space Interferometry Mission
The Space Interferometry Mission, or SIM, also known as SIM Lite , was a planned space telescope developed by the U.S. National Aeronautics and Space Administration , in conjunction with contractor Northrop Grumman...

 (2010), Laser Interferometer Space Antenna
Laser Interferometer Space Antenna
The Laser Interferometer Space Antenna is a planned space mission to detect and accurately measure gravitational waves from astronomical sources. LISA was originally conceived as a joint effort between the United States space agency NASA and the European Space Agency...

 (2011), and the International X-ray Observatory
International X-ray Observatory
The International X-ray Observatory was a planned X-ray telescope from about 2008 to 2011 by NASA, ESA, and JAXA. In 2011, NASA pulled out and ESA is forking/rebooting the project as the ESA Advanced Telescope for High ENergy Astrophysics ., which is an L-class candidate within the ESA Cosmic...

 (2011), leaving the telescope as the last big NASA astrophysics mission of its generation. With the cancellation of Project Constellation
Project Constellation
Constellation Program is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program were to gain significant experience in operating away from Earth's environment, develop technologies needed for opening the space frontier, and conduct...

 (2010) and the retirement of the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 (2011), it is one of NASA's only remaining big space projects.

The telescope's delays and cost increases can be compared to the Hubble space telescope. When it formally started in 1972, what came to be known as Hubble, had a then estimated development cost of $300 million USD (or about 1 billion USD in 2006 USD), but by the time it was sent into orbit in 1990, cost about four times that. In addition, new instruments and servicing missions increased the cost to at least 9 billion USD by 2006.

A 2006 article in Nature magazine noted a study in 1984 by the Space Science board, which estimated that a next generation infrared observatory would cost 4 billion USD (about 7 billion in 2006 dollars).

Other major telescope concepts that are either canceled, studies, or not approaching launch include MAXIM (Microarcsecond X-ray Imaging Mission), SAFIR (Single Aperture Far-Infrared Observatory), SUVO (Space Ultraviolet-Visible Observatory), SPECS (Submillimeter Probe of the Evolution of Cosmic Structure), and the aforementioned canceled TPF, SIM, LISA, and IXO.

Development



JWST is the maturation of the aforementioned Next Generation Space Telescope (NGST) plans. Some previously floated concepts include 8 meter aperture, 3 AU orbit, and NEXUS precursor telescope mission. A focus on the near to mid-infrared was preferred for three main reasons; high-redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

 objects have their visible emissions shifted into the infrared, cold objects such as debris disks and planets emit most strongly in the infrared, and this band is very hard to study from the ground, or by existing space telescopes such as Hubble.

JWST has a planned mass about half of Hubble, but its primary mirror (a 6.5 meter diameter gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

-coated beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...

 reflector) has a collecting area about 5 times larger (4.5 m2 vs. 25 m2). The JWST is oriented towards near infrared astronomy, but can also see orange and red visible light as well as the mid infrared region, depending on the instrument.

Early development work for a Hubble successor between 1989–1994, led to the Hi-Z telescope concept, a fully baffled 4 meter aperture infrared telescope going out to 3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 in its orbit. The distant orbit helped reduce light noise from zodiacal dust. In the "faster, better, cheaper" era in the mid-1990s, NASA leaders pushed for a space telescope with low-cost and 8 meter primary mirror diameter. The result was plans for a NGST for 500 million USD, 8 meter aperture, and located at L2. By 2002, as the concept matured into more of a technical reality, it was reduced to 6 meters aperture and the cost was estimated at around 2.5 Billion USD

Some concepts from early in development:

In 2002, TRW was bought by Northrop Grumman
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...


Understanding goals


JWST is the formal successor to the Hubble Space Telescope (HST)
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

, but since its primary emphasis is on infrared observation, it is equally fair to consider it a successor to the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...

. In fact, JWST will far surpass both those telescopes, being able to see many more and much older stars and galaxies. Observing in the infrared is a key technique for achieving this, because it better penetrates obscuring dust and gas, allows observation of dim cooler objects, and because of cosmological redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

.
Dust Penetration: Compare the two images of the Carina Nebula taken with the HST (left margin). Though both images are of the same astronomical object taken by HST, the top image was photographed utilizing the visible spectrum, whereas the bottom image was taken in the infrared, using the HST's WFC3
Wide Field Camera 3
The Wide Field Camera 3 is the Hubble Space Telescope's last and most technologically advanced instrument to take images in the visible spectrum...

 upgrade. Notice how more stars can be counted almost anywhere in the bottom image (infrared spectrum) than in the same corresponding location of the top image (visible spectrum). This demonstrates the power of infrared observations to penetrate the obscuration due to gas and dust that blocks much of the scene in visible spectrum images, so that the stars lying behind the gas and dust become easier to see.
Infrared astronomy
Infrared astronomy
Infrared astronomy is the branch of astronomy and astrophysics that studies astronomical objects visible in infrared radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers...

 can penetrate dusty regions of space, such as molecular cloud
Molecular cloud
A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen ....

s where stars are born, the circumstellar disks that give rise to planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...

s, and the cores of active galaxies which are often cloaked in gas and dust.

Cool objects: Furthermore, relatively cool objects (in this context meaning temperatures less than several thousand degrees) emit their radiation primarily in the infrared, as described by Planck's Law. As a result, most objects that are cooler than stars are better studied in the infrared. This includes the clouds of the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

, the "failed stars" called brown dwarfs, planets both in our own and other solar systems, and comets and Kuiper belt objects.

The distant universe: Looking beyond our own galaxy to more distant galaxy clusters, quasars, and gamma-ray bursts, the most distant objects viewable are also the "youngest," that is, they were formed during a time period closer in time to that of the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

. We see them today because their light has taken billions of years to reach us. Because the universe is expanding
Metric expansion of space
The metric expansion of space is the increase of distance between distant parts of the universe with time. It is an intrinsic expansion—that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space...

, as the light travels it becomes red-shifted and are therefore easier to see if viewed in the infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

. JWST's infrared capabilities are expected to let it see all the way to the very first galaxies forming just a few hundred million years after the big bang.

Mission


The JWST's primary scientific mission has four main components: to search for light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 from the first star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s and galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

 which formed in the Universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

 after the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

, to study the formation and evolution of galaxies
Galaxy formation and evolution
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby...

, to understand the formation of stars
Star formation
Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy star formation includes the study of the interstellar medium and giant molecular clouds as precursors to the star formation process and the study of young...

 and planetary systems and to study planetary system
Planetary system
A planetary system consists of the various non-stellar objects orbiting a star such as planets, dwarf planets , asteroids, meteoroids, comets, and cosmic dust...

s and the origins of life. All of these jobs can be done more effectively by analyzing near-infrared light rather than light in the visible part of the spectrum. For this reason the JWST's instruments will not measure visible or ultraviolet light like the Hubble Telescope, but will have a much greater capacity to collect infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 light. In its present design, the JWST will detect a range of wavelengths from 0.6 (orange light) to 28 micrometer
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

s (deep infrared radiation at about 100 K).

Due to a combination of redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

, dust obscuration, and the low temperatures of many of the sources to be studied, the JWST must be able to measure infrared light with a very high degree of precision. To ensure that infrared emissions coming from the telescope or its instruments do not interfere with these observations, the entire observatory must operate at a very low temperature. Moreover, it must be well shielded from radiation coming from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 and the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. To accomplish this, the JWST incorporates a large metalized fan-fold sunshield
Cold shield
A cold shield is a device to protect an object from unwanted heating by thermal radiation or light. Usually it is a cooled object with low absorption and high reflectivity....

, which will unfurl to block infrared radiation and allow the telescope to radiatively cool down to roughly 40 K. The telescope's location at the Sun-Earth Lagrange point ensures that the Earth and Sun occupy roughly the same relative position in the telescope's view and thus make the operation of this shield possible.

The observatory is currently scheduled to be launched by an Ariane 5
Ariane 5
Ariane 5 is, as a part of Ariane rocket family, an expendable launch system used to deliver payloads into geostationary transfer orbit or low Earth orbit . Ariane 5 rockets are manufactured under the authority of the European Space Agency and the Centre National d'Etudes Spatiales...

 from Guiana Space Centre Kourou
Kourou
Kourou is a commune in French Guiana, an overseas region and department of France located in South America.Kourou is the location of the Guiana Space Centre, France and ESA's main spaceport.-Geography:...

, French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...

 into an orbit with a launch mass of approximately After a commissioning period of approximately six months the observatory will begin the science mission which is expected to last a minimum of five years. The potential for extension of the science mission beyond this period exists and the observatory is being designed accordingly.

Orbit




The orbit of the JWST will be an elliptical orbit (with a radius of 800000 kilometres (497,098.2 mi)) around the semi-stable second Lagrange point, or . The Earth-Sun point, about which the Webb telescope will orbit, is 1500000 kilometres (932,059.1 mi) from the Earth, nearly 4 times farther than the distance between the Earth to the Moon. At such a great distance, the Webb telescope would be more difficult to service after launch than the Hubble telescope. Nevertheless, a docking ring was added to the design in 2007 to facilitate this possibility, either by a robot or future crewed spacecraft such as MPCV
Multi-Purpose Crew Vehicle
The Orion Multi-Purpose Crew Vehicle is a planned spacecraft that is being built by Lockheed Martin for NASA, the space agency of the United States, based on designs and tests already completed for the Orion spacecraft. The MPCV was announced by NASA on May 24, 2011...

.

Normally, an object circling the Sun further out than the Earth would take more than one year to complete its orbit. However, the balance of gravitational pull at the point (in particular, the extra pull from Earth as well as the Sun) means that JWST will keep up with the Earth as it goes around the Sun. The combined gravitational forces of the Sun and the Earth can hold a spacecraft at this point, so that in theory it takes no rocket thrust to keep a spacecraft in orbit around . In reality, the stable point is comparable to that of a ball balanced upon a saddle shape. Along one direction any perturbation will drive the ball toward the stable point, while in the crossing direction the ball, if disturbed, will fall away from the stable point. Thus some station-keeping is required, but with little energy expended (only 2–4 m/s per year, from the total budget of 150 m/s).

Since the JWST must be kept very cold to make accurate observations of distant astronomical objects, it has been designed with a large sunshield
Cold shield
A cold shield is a device to protect an object from unwanted heating by thermal radiation or light. Usually it is a cooled object with low absorption and high reflectivity....

 that blocks light and heat from the Sun. In order for such a shield to work properly, the Sun's rays must be constantly coming from the same direction. To achieve this outcome, JWST will be put into a relatively large "halo orbit" around . From the point itself, the Earth eclipses 90% of the disk of the Sun at all times and neither one appears to move at all, though lateral movement of the Moon can be seen. However, the radius of the Webb telescope's orbit around will be so large that neither the Earth nor Moon will eclipse the Sun, allowing the shield to deal with a relatively constant sunlight environment. This was considered to be more important than attempting to utilize the Earth's shadow to block some of the sunlight, in an orbit nearer the exact L2 point.

Optical design


JWST's primary mirror is a 6.5 meter diameter gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

-coated beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...

 reflector with a collecting area of 25 m2. This is too large for contemporary launch vehicles, so the mirror is composed of 18 hexagonal segments, which will unfold after the telescope is launched. Image plane wavefront sensing through phase retrieval will be used to position the mirror segments in the correct location using very precise micro-motors. Subsequent to this initial configuration they will only need occasional updates every few days to retain optimal focus. This is unlike terrestrial telescopes like the Keck
Keck telescopes
The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of near the summit of Mauna Kea in Hawai'i. The primary mirrors of each of the two telescopes are in diameter, making them the second largest optical telescopes in the world, slightly behind the Gran Telescopio...

 which continually adjust their mirror segments using active optics
Active optics
Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, mechanical stress...

 to overcome the effects of gravitational and wind loading, and is made possible because of the lack of environmental disturbances to a telescope in space.

JWST's optical design is a so-called three-mirror anastigmat, which makes use of curved secondary and tertiary mirrors to deliver images that are free of optical aberrations over a wide field. In addition there is a fast steering mirror, which can adjust its position many times a second to provide image stabilization
Image stabilization
Image stabilization is a family of techniques used to reduce blurring associated with the motion of a camera during exposure. Specifically, it compensates for pan and tilt of a camera or other imaging device. It is used in image-stabilized binoculars, still and video cameras, and astronomical...

.

Ball Aerospace & Technologies Corp. is the principal optical subcontractor for the JWST program, led by prime contractor Northrop Grumman Aerospace Systems
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...

, under a contract from the NASA Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

, in Greenbelt, Maryland
Greenbelt, Maryland
Greenbelt is a city in Prince George's County, Maryland, United States. Contained within today's City of Greenbelt is the historic planned community now known locally as "Old Greenbelt" and designated as the Greenbelt Historic District...

. Eighteen primary mirror segments, secondary, tertiary and fine steering mirrors, plus flight spares have been fabricated and polished by Ball Aerospace based on beryllium segment blanks manufactured by includes Axsys, Brush Wellman, and Tinsley Laboratories. As of June 2011, the first set of six fully completed mirror segments, including rigid supporting frames and cryogenic actuators, is undergoing final testing at NASA Marshall Space Flight Center
Marshall Space Flight Center
The George C. Marshall Space Flight Center is the U.S. government's civilian rocketry and spacecraft propulsion research center. The largest center of NASA, MSFC's first mission was developing the Saturn launch vehicles for the Apollo moon program...

; testing all of the remaining mirrors will be complete by fall 2011

Scientific instruments


The Integrated Science Instrument Module (ISIM) contains four science instruments and a guide camera.

NIRCam (Near InfraRed Camera) is an infrared imager which will have a spectral coverage ranging from the edge of the visible through the near infrared . NIRCam will also serve as the observatory's wavefront sensor, which is required for wavefront sensing and control activities. NIRCam is being built by a team led by the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

, with Principal Investigator Marcia Rieke. The industrial partner is Lockheed-Martin's Advanced Technology Center located in Palo Alto, California.

The observatory will also perform spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

 over the same wavelength range with the NIRSpec (Near InfraRed Spectrograph). NIRSpec is being built by the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 at ESTEC in Noordwijk
Noordwijk
Noordwijk is a town and municipality in the western Netherlands, in the province of South Holland. The municipality covers an area of 51.53 km² and had a population of 24,707 in May 2006....

, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, leading a team involving EADS Astrium
EADS Astrium
Astrium Satellites is one of the three business units of Astrium, a subsidiary of EADS. It is a European space manufacturer involved in the manufacture of spacecraft used for science, Earth observation and telecommunication, as well as the equipment and subsystems used therein and related ground...

, Ottobrunn, and Friedrichshafen, Germany, and the Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

: the NIRSpec project scientist is Peter Jakobsen. The NIRSpec design provides 3 observing modes: a low resolution mode using a prism, an R~1000 multi-object mode and an R~2700 integral field unit or long-slit spectroscopy mode. Switching of the modes is done by operating a wavelength preselection mechanism called Filter Wheel Assembly and selecting a correspondent dispersive element (prism or grating) using the Grating Wheel Assembly mechanism. Both mechanisms are based on the successful ISOPHOT wheel mechanisms of the Infrared Space Observatory
Infrared Space Observatory
The Infrared Space Observatory was a space telescope for infrared light designed and operated by the European Space Agency , in cooperation with ISAS and NASA...

. The multi-object mode relies on a complex micro-shutter mechanism to allow for simultaneous observations of hundreds of individual objects anywhere in NIRSpec's field of view. The mechanisms and their optical elements are being designed, integrated and tested by Carl Zeiss Optronics GmbH of Oberkochen, Germany, under contract from Astrium.

The mid-infrared wavelength range from 5 to 27 micrometers will be measured by the MIRI (Mid InfraRed
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 Instrument), which contains both a mid-IR camera and an imaging spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

. MIRI is being developed as a collaboration between NASA and a consortium of European countries, and is led by George Rieke (University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

) and Gillian Wright (UK Astronomy Technology Centre
UK Astronomy Technology Centre
The UK Astronomy Technology Centre is based at the Royal Observatory in Edinburgh, Scotland, and is part of the Science and Technology Facilities Council....

, Edinburgh, part of the Science and Technology Facilities Council (STFC)). MIRI features similar wheel mechanisms as NIRSpec which are also developed and built by Carl Zeiss Optronics GmbH under contract from the Max Planck Institute for Astronomy
Max Planck Institute for Astronomy
The Max-Planck-Institut für Astronomie is a research institute of the Max Planck Society. It is located in Heidelberg, Baden-Württemberg, Germany near the top of the Koenigstuhl, adjacent to the historic Landessternwarte Heidelberg-Königstuhl astronomical observatory.The institute was founded in...

, Heidelberg.

The FGS (Fine Guidance Sensor), led by the Canadian Space Agency under project scientist John Hutchings (Herzberg Institute of Astrophysics
Herzberg Institute of Astrophysics
The NRC Herzberg Institute of Astrophysics is the leading Canadian centre for astronomy and astrophysics.Named for the Nobel laureate Gerhard Herzberg, it was formed in 1975 as part of the National Research Council of Canada in Ottawa, Ontario...

, National Research Council of Canada
National Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...

), is used to stabilize the line-of-sight of the observatory during science observations. Measurements by the FGS are used both to control the overall orientation of the spacecraft and to drive the fine steering mirror for image stabilization
Image stabilization
Image stabilization is a family of techniques used to reduce blurring associated with the motion of a camera during exposure. Specifically, it compensates for pan and tilt of a camera or other imaging device. It is used in image-stabilized binoculars, still and video cameras, and astronomical...

. The Canadian Space Agency is also providing a Tunable Filter Imager (TFI) module for astronomical narrow-band imaging in the wavelength range, led by principal investigator René Doyon at the University of Montreal. Because the TFI is physically mounted together with the FGS, they are often referred to as a single unit, but they serve entirely different purposes, with one being a scientific instrument and the other being a part of the observatory's support infrastructure.

NIRCam, MIRI, and TFI all feature starlight-blocking coronagraph
Coronagraph
A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved...

s for observation of faint targets such as extrasolar planets and circumstellar disks very close to bright stars.

The infrared detectors for the NIRCam, NIRSpec, FGS, and TFI modules are being provided by Teledyne Imaging Sensors (formerly Rockwell Scientific Company).

Construction and engineering


NASA's Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

 in Greenbelt, Maryland, is leading the management of the observatory project. The project scientist for the James Webb Space Telescope is John C. Mather
John C. Mather
John Cromwell Mather is an American astrophysicist, cosmologist and Nobel Prize in Physics laureate for his work on the Cosmic Background Explorer Satellite with George Smoot. COBE was the first experiment to measure ".....

. Northrop Grumman
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...

 Aerospace Systems serves as the primary contractor for the development and integration of the observatory. They are responsible for developing and building the spacecraft element, which includes both the spacecraft bus and sunshield. Ball Aerospace
Ball Aerospace
Ball Aerospace & Technologies Corp. is a manufacturer of spacecraft, components, and instruments for national defense, civil space and commercial space applications. The company is a wholly owned subsidiary of Ball Corp...

 has been subcontracted to develop and build the Optical Telescope Element (OTE). Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

 is also responsible for providing the Integrated Science Instrument Module (ISIM).

NASA is considering plans to add a grapple feature so future spacecraft might visit the observatory to fix gross deployment problems, such as a stuck solar panel or antenna. However, the telescope itself would not be serviceable, so that astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope. Final approval for such an addition was to be considered as part of the Preliminary Design Review in March 2008.

Most of the data processing on the telescope is done by conventional single board computers. The conversion of the analog science data to digital form is performed by the custom-built SIDECAR ASIC (System for Image Digitization, Enhancement, Control And Retrieval Application Specific Integrated Circuit
Application-specific integrated circuit
An application-specific integrated circuit is an integrated circuit customized for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC...

). It is said that the SIDECAR ASIC will include all the functions of a 20-pound instrument box in a package the size of a half-dollar, and consume only of power. Since this conversion must be done close to the detectors, on the cool side of the telescope, the low power use of this IC will be important for maintaining the low temperature required for optimal operation of the JWST.

Ground support and operations


The Space Telescope Science Institute
Space Telescope Science Institute
The Space Telescope Science Institute is the science operations center for the Hubble Space Telescope and for the James Webb Space Telescope...

 (STScI) in Baltimore, Maryland has been selected as the Science and Operations Center (S&OC) for JWST. In this capacity, STScI will be responsible for the scientific operation of the telescope and delivery of data products to the astronomical community. Data will be transmitted from JWST to the ground via NASA's Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

, processed and calibrated at STScI, and then distributed online to astronomers worldwide. Similar to how Hubble is operated, anyone, anywhere in the world, will be allowed to submit proposals for observations. Each year several committees of astronomers will peer review
Peer review
Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...

 the submitted proposals to select the programs to observe in the coming year. The authors of the chosen proposals will typically have one year of private access to the new observations, after which the data will become publicly available for download by anyone from the online archive at STScI.

Program status



The mission had been working towards a launch date in 2014, but during the summer of 2010 an independent review panel determined that 2015 was the earliest possible launch date, and even that would require a significant influx of additional funding. Notably, this review commended the JWST project for being in excellent technical shape with most flight hardware making good progress to completion. The delay and cost overruns are due to an unrealistic original budget and insufficient program management. In response, NASA instituted significant management changes in the JWST project, but the need for increased funding has led to a substantial mission delay. As of June 2011, it appears likely that JWST will launch no sooner than 2017
or 2018. A more specific launch date plan should become determined by the end of 2011, pending the FY2012 US federal budget process.

By 2011, the JWST program is in the final design and fabrication phase (Phase C). As is typical for a complex design that cannot be changed once launched, there are detailed reviews of every portion of design, construction, and proposed operation. New technological frontiers have been pioneered by the program, and it has passed its design reviews. In the 1990s it was unknown if a telescope so large and light was possible.
In April 2006, the program was independently reviewed following a re-planning phase begun in August 2005. The review concluded the program was technically sound, but that funding phasing at NASA needed to be changed. NASA has re-phased its JWST budgets accordingly. The August 2005 re-planning was necessitated by the cost growth revealed in Spring 2005. The primary technical outcomes of the re-planning are significant changes in the integration and test plans, a 22-month launch delay (from 2011 to 2013), and elimination of system level testing for observatory modes at wavelength shorter than 1.7 micrometers. Other major features of the observatory are unchanged following the re-planning efforts.

Selected Events
Year Events
1996 NGST started
2002 named JWST, 8 to 6 m
2004 NEXUS cancelled
2007 esa/nasa MOU
2010 MCDR passed
2011 Proposed cancel


As of the 2005 re-plan, the life-cycle cost of the project was estimated at about US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

4.5 billion. This comprises approximately US$3.5 billion for design, development, launch and commissioning, and approximately US$1.0 billion for ten years of operations. ESA is contributing about
Euro
The euro is the official currency of the eurozone: 17 of the 27 member states of the European Union. It is also the currency used by the Institutions of the European Union. The eurozone consists of Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg,...

300 million, including the launch, and the Canadian Space Agency about $39M Canadian. costs were still on target, but by 2010 cost over-runs were impacting other programs, though JWST itself remains on schedule.

In January 2007, nine of the ten technology development items in the program successfully passed a non-advocate review. These technologies were deemed sufficiently mature to retire significant risks in the program. The remaining technology development item (the MIRI cryocooler) completed its technology maturation milestone in April 2007. This technology review represented the beginning step in the process that ultimately moved the program into its detailed design phase (Phase C).

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 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 will 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 a process called the Independent Comprehensive Review Panel, which led to a re-plan of the mission aiming for 2015, but as late as 2018. The spacecraft design, which passed a preliminary review in 2009, will continue toward final approval in 2011.
In April 2011, cryogenic testing of a six-mirror array began. This test is to ensure the mirrors perform to specifications at the temperatures they will encounter.

In July 2011, the United States House of Representatives
United States House of Representatives
The United States House of Representatives is one of the two Houses of the United States Congress, the bicameral legislature which also includes the Senate.The composition and powers of the House are established in Article One of the Constitution...

 Appropriations Committee on Commerce, Justice and Science proposed cancelling the telescope project because it "is billions of dollars over budget and plagued by poor management". The estimated cost had risen to $6.5 billion at that time. As of August 2011, it is estimated to cost 8.7 Billion USD for the telescope and five years of operation, and launch in 2018.AFP - NASA boosts Webb telescope cost to $8.7 billion (Google 2011) However, on November 18, 2011 the first appropriations bill of the 2012 United States federal budget
2012 United States federal budget
The 2012 United States federal budget is the United States federal budget to fund government operations for the fiscal year 2012, which is October 2011–September 2012...

 was passed, maintaining funding for the telescope.

Reported cost and schedule issues

Then-planned launch & costs
Year Launch Budget Plan
1997 2007 0.5 Billion USD
1998 2007 1
1999 2007 to 2008 1
2000 2009 1.8
2002 2010 2.5
2003 2011 2.5
2005 2013 3
2006 2014 4.5
2008 2014 5.1
2010 2015 to 2016 6.5
2011 2018 8.7


In June 2011, it was reported that the Webb telescope will cost at least four times more than originally proposed, and launch at least seven years late. Initial budget estimates were that the observatory would cost $1.6 billion and launch in 2011. NASA has now scheduled the telescope for a 2018 launch, though outside analysts suggest the flight could slip past 2020. The latest estimated price tag for the telescope is now $6.8 billion.

Some scientists have expressed concerns about growing costs and schedule delays for the Webb telescope, which they see as competing for scant astronomy budgets and thus threatening funding for other space science programs. A review of NASA budget records and status reports by journalists at Florida Today show the Webb observatory is plagued by many of the same problems that have plagued several other major NASA projects. Mistakes included: underestimates of the telescope’s cost that failed to budget for expected technical glitches, and failure to act on warnings that budgets were being exceeded, thus extending the schedule and increasing costs further.

Proposed U.S. withdrawal


On 6 July 2011, the United States House of Representatives' appropriations committee on Commerce, Justice, and Science moved to cancel the James Webb project by proposing an FY2012 budget that removed $1.9bn from NASA's overall budget, of which roughly one quarter was for JWST. This budget proposal was approved by subcommittee vote the following day, but it remains to be seen how the rest of the US House of Representatives and Senate will weigh in on this issue during the ongoing federal budget negotiations.. In November 2011, congress reversed plans to cancel the JWST and instead capped additional funding to complete the project at $8 billion.

The committee charged that the project was "billions of dollars over budget and plagued by poor management". The telescope was originally estimated to cost $1.6bn but the cost estimate grew throughout the early development reaching about $5bn by the time the mission was formally confirmed for construction start in 2008. In summer 2010, the mission passed its Critical Design Review with excellent grades on all technical matters, but schedule and cost slips at that time prompted US Senator Barbara Mikulski to call for an independent review of the project. The Independent Comprehensive Review Panel (ICRP) chaired by J. Casani (JPL) found that the earliest launch date was in late 2015 at an extra cost of $1.5bn (for a total of $6.5bn). They also pointed out that this would have required extra funding in FY2011 and FY2012 and that any later launch date would lead to a higher total cost. Because the runaway budget diverted funding from other research, the science journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

described the James Webb as "the telescope that ate astronomy". However, termination of the project as proposed by the House appropriation committee does not provide funding to other missions as the JWST line is simply terminated with the funding simply leaving astrophysics (and leaving the NASA budget) entirely.

The American Astronomical Society
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...

 has issued a statement in support of JWST, as did US Senator Barbara Mikulski
Barbara Mikulski
Barbara Ann Mikulski is the senior United States Senator from Maryland and a member of the Democratic Party. Mikulski, a former U.S. Representative, is the longest-serving female senator in U.S...

. A number of editorials supporting JWST have appeared in the international press

A review of the program released in August 2011, says the cost for the telescope and 5 years of operations will be 8.7 Billion USD with a planned launch in 2018. Of that price about 800 million USD is for the 5 years of operations. By September 2011, NASA will have spent 3.5 billion USD.

However, on November 18, 2011 the Consolidated and Further Continuing Appropriations Act, 2012, the first appropriations bill of the 2012 United States federal budget
2012 United States federal budget
The 2012 United States federal budget is the United States federal budget to fund government operations for the fiscal year 2012, which is October 2011–September 2012...

, was enacted, maintaining funding for the telescope.

Public displays



A large telescope model has been on display at various places since 2005: Seattle, Washington
Seattle, Washington
Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...

; Colorado Springs, Colorado
Colorado Springs, Colorado
Colorado Springs is a Home Rule Municipality that is the county seat and most populous city of El Paso County, Colorado, United States. Colorado Springs is located in South-Central Colorado, in the southern portion of the state. It is situated on Fountain Creek and is located south of the Colorado...

; Paris, France; Greenbelt, Maryland
Greenbelt, Maryland
Greenbelt is a city in Prince George's County, Maryland, United States. Contained within today's City of Greenbelt is the historic planned community now known locally as "Old Greenbelt" and designated as the Greenbelt Historic District...

; Rochester, New York
Rochester, New York
Rochester is a city in Monroe County, New York, south of Lake Ontario in the United States. Known as The World's Image Centre, it was also once known as The Flour City, and more recently as The Flower City...

; Orlando, Florida
Orlando, Florida
Orlando is a city in the central region of the U.S. state of Florida. It is the county seat of Orange County, and the center of the Greater Orlando metropolitan area. According to the 2010 US Census, the city had a population of 238,300, making Orlando the 79th largest city in the United States...

; Dublin, Ireland; Montreal, Canada; Hatfield, United Kingdom
Hatfield, Hertfordshire
Hatfield is a town and civil parish in Hertfordshire, England in the borough of Welwyn Hatfield. It has a population of 29,616, and is of Saxon origin. Hatfield House, the home of the Marquess of Salisbury, is the nucleus of the old town...

; Munich, Germany; and Manhattan, New York. The model was built by the main contractor, Northrop Grumman
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...

 Aerospace Systems.

In May 2007, a full-scale model of the telescope was assembled for display at the Smithsonian's National Air and Space Museum
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...

 on the National Mall
National Mall
The National Mall is an open-area national park in downtown Washington, D.C., the capital of the United States. The National Mall is a unit of the National Park Service , and is administered by the National Mall and Memorial Parks unit...

, Washington DC. The model was intended to give the viewing public a better understanding of the size, scale and complexity of the satellite. The model is significantly different from the telescope, as the model must withstand gravity and weather, so is constructed mainly of aluminum and steel measuring approximately 24 x and weighs 5.5 tonnes (12,125.4 lb).

More recently, the model was on ongoing display in New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

's Battery Park
Battery Park
Battery Park is a 25-acre public park located at the Battery, the southern tip of Manhattan Island in New York City, facing New York Harbor. The Battery is named for artillery batteries that were positioned there in the city's early years in order to protect the settlement behind them...

 during the 2010 World Science Festival
World Science Festival
The World Science Festival is a science festival held in New York City that is held annually in the summer. The 2008 inaugural festival was held May 28 – June 1 and consisted mainly of panel discussions and on-stage conversations, accompanied by multimedia presentations.The festival was the...

. It served as the backdrop for a panel discussion featuring Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 laureate John C. Mather
John C. Mather
John Cromwell Mather is an American astrophysicist, cosmologist and Nobel Prize in Physics laureate for his work on the Cosmic Background Explorer Satellite with George Smoot. COBE was the first experiment to measure ".....

, astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....

 John Grunsfeld and astronomer Heidi Hammel, which was followed by a star party
Star party
A star party is a gathering of amateur astronomers for the purpose of observing the sky. Local star parties may be one night affairs, but larger events can last up to a week or longer and attract hundreds or even thousands of participants. Many regional star parties are now held annually and are an...

 hosted by Neil deGrasse Tyson
Neil deGrasse Tyson
Neil deGrasse Tyson is an American astrophysicist, a science communicator, the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space, and a Research Associate in the Department of Astrophysics at the American Museum of Natural History...

, the director of the city's Hayden Planetarium
Hayden Planetarium
The Hayden Planetarium is a public planetarium, part of the Rose Center for Earth and Space of the American Museum of Natural History in New York City, currently directed by astrophysicist Dr. Neil deGrasse Tyson....

.

A model is on display at the front of the Maryland Science Center
Maryland Science Center
The Maryland Science Center, located in Baltimore's Inner Harbor, opened to the public in 1976. It includes three levels of exhibits, a planetarium, and an observatory. It was one of the original structures that drove the revitalization of the Baltimore Inner Harbor from its industrial roots to a...

from October 18-31.

The Plan


Further reading

The formal case for the JWST science, plus some implementation.

Countries



External links


(NASA) (STScI), (ESA)
Science instrument teams:
Background: