The James Webb Space Telescope (JWST) is a
space telescope
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launch ...
which conducts
infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in betw ...
. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old,
distant, or faint for the
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 vers ...
.
This will enable investigations across many fields of
astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
and
cosmology
Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...
, such as observation of the
first stars, the
formation of the first galaxies, and detailed atmospheric characterization of
potentially habitable exoplanet
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from a ...
s.
The U.S.
National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the
European Space Agency (ESA) and the
Canadian Space Agency (CSA). The NASA
Goddard Space Flight Center (GSFC) in
Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
managed telescope development, the
Space Telescope Science Institute
The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for the ...
in
Baltimore
Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
on the
Homewood Campus of Johns Hopkins University The Homewood Campus is the main academic and administrative center of the Johns Hopkins University. It is located at 3400 North Charles Street in Baltimore, Maryland. It houses the two major undergraduate schools: the Zanvyl Krieger School of Arts a ...
operates JWST, and the prime contractor was
Northrop Grumman
Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military techn ...
. The
telescope is named after
James E. Webb
James Edwin Webb (October 7, 1906 – March 27, 1992) was an American government official who served as Undersecretary of State from 1949 to 1952. He was the second Administrator of NASA from February 14, 1961, to October 7, 1968. Webb led NAS ...
, who was the
administrator of NASA
The Administrator of the National Aeronautics and Space Administration is the highest-ranking official of NASA, the national space agency of the United States. The administrator is NASA's chief decision maker, responsible for providing clarity to ...
from 1961 to 1968 during the
Mercury,
Gemini
Gemini may refer to:
Space
* Gemini (constellation), one of the constellations of the zodiac
** Gemini in Chinese astronomy
* Project Gemini, the second U.S. crewed spaceflight program
* Gemini Observatory, consisting of telescopes in the Norther ...
, and
Apollo
Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label= Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label ...
programs.
The James Webb Space Telescope was launched on 25 December 2021 on an
Ariane 5 rocket from
Kourou
Kourou () is a commune in French Guiana, an overseas region and department of France in South America. Kourou is famous for being the location of the Guiana Space Centre, the main spaceport of France and the European Space Agency (ESA). It i ...
,
French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
, and arrived at the Sun–Earth
L2 Lagrange point in January 2022.
The first JWST image was released to the public via a press conference on 11 July 2022.
JWST's
primary mirror
A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Description
The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
consists of 18 hexagonal
mirror segments made of gold-plated
beryllium
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...
, which combined create a mirror, compared with
Hubble's . This gives JWST a
light-collecting area of about 25 square meters, about six times that of Hubble. Unlike Hubble, which observes in the
near ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
and
visible
Visibility, in meteorology, is a measure of the distance at which an object or light can be seen.
Visibility may also refer to:
* A measure of turbidity in water quality control
* Interferometric visibility, which quantifies interference contrast ...
(0.1 to 0.8 μm), and
near infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from arou ...
(0.8–2.5 μm)
[ spectra, JWST observes in a lower frequency range, from long-wavelength visible ]light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
(red) through mid-infrared (0.6–28.3 μm). The telescope must be kept extremely cold, below , such that the infrared light emitted by the telescope itself does not interfere with the collected light. It is deployed in a solar orbit near the Sun–Earth L2 Lagrange point, about from Earth, where its five-layer sunshield protects it from warming by the Sun, Earth, and Moon.
Initial designs for the telescope, then named the Next Generation Space Telescope, began in 1996. Two concept studies were commissioned in 1999, for a potential launch in 2007 and a US$1 billion budget. The program was plagued with enormous cost overruns and delays; a major redesign in 2005 led to the current approach, with construction completed in 2016 at a total cost of US$10 billion. The high-stakes nature of the launch and the telescope's complexity were remarked upon by the media, scientists, and engineers.
Features
The James Webb Space Telescope has a mass that is about half of 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 vers ...
's mass. The JWST has a -diameter gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...
-coated beryllium
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...
primary mirror
A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Description
The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
made up of 18 separate hexagonal mirrors. The mirror has a polished area of , of which is obscured by the secondary support struts, giving a total collecting area of . This is over six times larger than the collecting area of Hubble's diameter mirror, which has a collecting area of . The mirror has a gold coating to provide infrared reflectivity
The reflectance of the surface of a material is its effectiveness in Reflection (physics), reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the respon ...
and this is covered by a thin layer of glass for durability.
JWST is designed primarily for near-infrared astronomy, but can also see orange and red visible light, as well as the mid-infrared region, depending on the instrument. It can detect objects up to 100 times fainter than Hubble can, and objects much earlier in the history of the universe
History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well ...
, back to redshift z≈20 (about 180 million years cosmic time
Cosmic time, or cosmological time, is the time coordinate commonly used in the Big Bang models of physical cosmology. Such time coordinate may be defined for a homogeneous, expanding universe so that the universe has the same density everywhere ...
after the Big Bang). For comparison, the earliest stars are thought to have formed between z≈30 and z≈20 (100–180 million years cosmic time), and the first galaxies may have formed around redshift z≈15 (about 270 million years cosmic time). Hubble is unable to see further back than very early reionization
In the fields of Big Bang theory and cosmology, reionization is the process that caused matter in the universe to reionize after the lapse of the " dark ages".
Reionization is the second of two major phase transitions of gas in the universe (t ...
at about z≈11.1 (galaxy GN-z11
GN-z11 is a high-redshift galaxy found in the constellation Ursa Major. It is one of the farthest known galaxies from Earth ever discovered. The 2015 discovery was published in a 2016 paper headed by Pascal Oesch and Gabriel Brammer (Cosmic Dawn ...
, 400 million years cosmic time).[
The design emphasizes the near to mid-infrared for several reasons:
* high- redshift (very early and distant) objects have their visible emissions shifted into the infrared, and therefore their light can be observed today only via infrared ]astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
;
* infrared light passes more easily through dust clouds than visible light;
* colder objects such as debris disk
A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris di ...
s and planets emit most strongly in the infrared;
* these infrared bands are difficult to study from the ground or by existing space telescopes such as Hubble.
Ground-based telescopes must look through Earth's atmosphere, which is opaque in many infrared bands (see figure at right). Even where the atmosphere is transparent, many of the target chemical compounds, such as water, carbon dioxide, and methane, also exist in the Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...
, vastly complicating analysis. Existing space telescopes such as Hubble cannot study these bands since their mirrors are insufficiently cool (the Hubble mirror is maintained at about ) which means that the telescope itself radiates strongly in the relevant infrared bands.
JWST can also observe objects in the Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
at an angle of more than 85° from the Sun and having an apparent angular rate of motion less than 0.03 arc seconds per second. This includes Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, their satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...
s, and comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s, asteroids and minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''mino ...
s at or beyond the orbit of Mars
Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million km), and an eccentricity of 0.0934.Jean Meeus, ''Astronomical Formulæ for Calculators''. (Richmond, VA: Willmann-Bell, 1988) 99. Elements by F. E. Ross The planet o ...
. JWST has the near-IR and mid-IR sensitivity to be able to observe virtually all known Kuiper Belt Objects
The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...
. In addition, it can observe opportunistic and unplanned targets within 48 hours of a decision to do so, such as supernovae and gamma ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten millise ...
s.[
File:James Webb Space Telescope 2009 top.jpg, Three-quarter view of the top
File:James Webb Space Telescope 2009 bottom.jpg, Bottom (Sun-facing side)
]
Location and orbit
JWST operates in a halo orbit, circling around a point in space known as the Sun–Earth L2 Lagrange point, approximately beyond Earth's orbit around the Sun. Its actual position varies between about from L2 as it orbits, keeping it out of both Earth and Moon's shadow. By way of comparison, Hubble orbits above Earth's surface, and the Moon is roughly from Earth. Objects near this Sun–Earth point can orbit the Sun in synchrony with the Earth, allowing the telescope to remain at a roughly constant distance with continuous orientation of its sunshield and equipment bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
toward the Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
and Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
. Combined with its wide shadow-avoiding orbit, the telescope can simultaneously block incoming heat and light from all three of these bodies and avoid even the smallest changes of temperature from Earth and Moon shadows that would affect the structure, yet still maintain uninterrupted solar power and Earth communications on its sun-facing side. This arrangement keeps the temperature of the spacecraft constant and below the necessary for faint infrared observations.[ ]
Sunshield protection
To make observations in the infrared spectrum
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
, JWST must be kept under ; otherwise, infrared radiation from the telescope itself would overwhelm its instruments. Its large sunshield blocks light and heat from the Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, and Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
, and its position near the Sun–Earth keeps all three bodies on the same side of the spacecraft at all times. Its halo orbit around the L2 point avoids the shadow of the Earth and Moon, maintaining a constant environment for the sunshield and solar arrays. The resulting stable temperature for the structures on the dark side is critical to maintaining precise alignment of the primary mirror segments.
The five-layer sunshield, each layer as thin as a human hair, is made of Kapton E
Structure of poly-oxydiphenylene-pyromellitimide
Kapton insulating pads for mounting electronic parts on a heat sink
Kapton is a polyimide film used in flexible printed circuits ( flexible electronics) and space blankets, which are used on spa ...
film, coated with aluminum on both sides and a layer of doped silicon
In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic se ...
on the Sun-facing side of the two hottest layers to reflect the Sun's heat back into space. Accidental tears of the delicate film structure during deployment testing in 2018 led to further delays to the telescope.
The sunshield was designed to be folded twelve times (concertina style) so that it would fit within the Ariane 5 rocket's payload fairing, which is in diameter, and long. The shield's fully deployed dimensions were planned as .
Keeping within the shadow of the sunshield limits the field of regard The field of regard (abbreviated FOR) is the total area that can be captured by a movable sensor. It should not be confused with the field of view (FOV), which is the angular cone perceivable by the sensor at a particular time instant. The field of ...
of JWST at any given time. The telescope can see 40 percent of the sky from any one position, but can see all of the sky over a period of six months.
Optics
JWST's primary mirror
A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Description
The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
is a -diameter gold-coated beryllium reflector with a collecting area of . If it had been designed as a single large mirror, it would have been too large for existing launch vehicles. The mirror is therefore composed of 18 hexagonal segments (a technique pioneered by Guido Horn d'Arturo), which unfolded after the telescope was launched. Image plane wavefront sensing through phase retrieval
Phase retrieval is the process of algorithmically finding solutions to the phase problem. Given a complex signal F(k), of amplitude , F (k), , and phase \psi(k):
::F(k) = , F(k), e^ =\int_^ f(x)\ e^\,dx
where ''x'' is an ''M''-dimensional spatia ...
is used to position the mirror segment
A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be either spherical or asymmetric (if they are part of a larger parabolic reflector). They are used as objectives for ...
s in the correct location using very precise micro-motors. Subsequent to this initial configuration, they only need occasional updates every few days to retain optimal focus. This is unlike terrestrial telescopes, for example the Keck telescopes, which continually adjust their mirror segments using active optics to overcome the effects of gravitational and wind loading. The Webb telescope uses 132 small motors (called actuators) to position and occasionally adjust the optics. The actuators can position the mirror with 10 nanometer accuracy.
JWST's optical design is a three-mirror anastigmat
A three-mirror anastigmat is an anastigmat telescope built with three curved mirrors, enabling it to minimize all three main optical aberrations – spherical aberration, coma, and astigmatism. This is primarily used to enable wide fields of view, ...
, which makes use of curved secondary and tertiary mirrors to deliver images that are free from optical aberrations
In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. Aberrations cause the image formed by a lens to be blurred or distorted, with th ...
over a wide field. The secondary mirror is in diameter. In addition, there is a fine steering mirror which can adjust its position many times per second to provide image stabilization. Photographs taken by the JWST have six spikes
The SPIKES protocol is a method used in clinical medicine to break bad news to patients and families. As receiving bad news can cause distress and anxiety, clinicians need to deliver the news carefully. By using the SPIKES method for introducing a ...
plus two fainter ones due to the spider supporting the secondary mirror.
Scientific instruments
The Integrated Science Instrument Module
Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope, a large international infrared space telescope launched on . ISIM is the heart of the JWST, and holds the main science payload which includes four scien ...
(ISIM) is a framework that provides electrical power, computing resources, cooling capability as well as structural stability to the Webb telescope. It is made with bonded graphite-epoxy composite attached to the underside of Webb's telescope structure. The ISIM holds the four science instruments and a guide camera.[
* ]NIRCam
NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other wor ...
(Near Infrared Camera) is an infrared imager which has spectral coverage ranging from the edge of the visible (0.6 μm) through to the near infrared (5 μm). There are 10 sensors each of 4 megapixels. NIRCam serves as the observatory's wavefront sensor, which is required for wavefront sensing and control activities, used to align and focus the main mirror segments. NIRCam was built by a team led by the University of Arizona
The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory.
T ...
, with principal investigator Marcia J. Rieke
Marcia Jean Rieke ( ) is an American astronomer. She is a Regents' Professor of Astronomy and associate department head at the University of Arizona. Rieke is the Principal Investigator on the near-infrared camera (NIRCam) for the James Webb Spa ...
.
* NIRSpec
The NIRSpec (Near-Infrared Spectrograph) is one of the four scientific instruments flown on the James Webb Space Telescope (JWST). The JWST is the follow-on mission to the Hubble Space Telescope (HST) and is developed to receive more information ...
(Near Infrared Spectrograph) performs spectroscopy over the same wavelength range. It was built by the European Space Agency at ESTEC
The European Space Research and Technology Centre (ESTEC) is the European Space Agency's main technology development and test centre for spacecraft and space technology. It is situated in Noordwijk, South Holland, in the western Netherlands, alt ...
in Noordwijk
Noordwijk () is a town and municipality in the west of the Netherlands, in the province of South Holland. The municipality covers an area of of which is water and had a population of in .
On 1 January 2019, the former municipality of Noordwij ...
, Netherlands. The leading development team includes members from Airbus Defence and Space, Ottobrunn and Friedrichshafen, Germany, and the Goddard Space Flight Center; with Pierre Ferruit (École normale supérieure de Lyon
The École normale supérieure de Lyon (also known as ENS de Lyon, ENSL or Normale Sup' Lyon) is a French grande école located in the city of Lyon. It is one of the four prestigious écoles normales supérieures in France. The school is ...
) as NIRSpec project scientist. The NIRSpec design provides three 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 the Filter Wheel Assembly, and selecting a corresponding 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
The Infrared Space Observatory (ISO) was a space telescope for infrared light designed and operated by the European Space Agency (ESA), in cooperation with ISAS (now part of JAXA) and NASA. The ISO was designed to study infrared light at wavelengt ...
. 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. There are two sensors each of 4 megapixels.
* MIRI
)
, subdivision_type = Country
, subdivision_name =
, subdivision_type1 = State
, subdivision_name1 =
, subdivision_type2 = Division
, subdivision_name2 ...
(Mid-Infrared Instrument) measures the mid-to-long-infrared wavelength range from 5 to 27 μm.[ ] It contains both a mid-infrared camera and an imaging spectrometer
A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
.[ ] MIRI was developed as a collaboration between NASA and a consortium of European countries, and is led by George Rieke (University of Arizona
The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory.
T ...
) and Gillian Wright
Gillian Wright (born 5 May 1960) is an English actress, best known for portraying the role of Jean Slater on the BBC soap opera ''EastEnders'' since 2004, for which she has won a number of awards. She was a teacher and theatre director before ...
(UK Astronomy Technology Centre
The UK Astronomy Technology Centre (UK ATC) is based at the Royal Observatory in Edinburgh, Scotland, and is part of the Science and Technology Facilities Council.
The UK ATC designs, builds, develops, tests and manages major instrumentation ...
, Edinburgh
Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian on the southern shore of t ...
, Scotland). The temperature of the MIRI must not exceed : a helium gas mechanical cooler sited on the warm side of the environmental shield provides this cooling.
* FGS/NIRISS (Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph), led by the Canadian Space Agency under project scientist John Hutchings ( Herzberg Astronomy and Astrophysics Research Centre), 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. The Canadian Space Agency also provided a Near Infrared Imager and Slitless Spectrograph (NIRISS) module for astronomical imaging and spectroscopy in the 0.8 to 5 μm wavelength range, led by principal investigator René Doyon at the Université de Montréal
The Université de Montréal (UdeM; ; translates to University of Montreal) is a French-language public research university in Montreal, Quebec, Canada. The university's main campus is located in the Côte-des-Neiges neighborhood of Côte- ...
. Although they are often referred together as a unit, the NIRISS and FGS serve entirely different purposes, with one being a scientific instrument and the other being a part of the observatory's support infrastructure.
NIRCam and MIRI feature starlight-blocking 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. Most coronagraphs are intended to view t ...
s for observation of faint targets such as extrasolar planets
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
and circumstellar disks
A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the re ...
very close to bright stars.[
]
Spacecraft bus
The spacecraft bus
A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held.
Bus-derived satellites are opposed to specially produced satellites. Bus- ...
is the primary support component of the James Webb Space Telescope, hosting a multitude of computing, communication, electric power, propulsion, and structural parts.[ ] Along with the sunshield, it forms the spacecraft element of the space telescope
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launch ...
.[ ][ ] The spacecraft bus is on the Sun-facing "warm" side of the sunshield and operates at a temperature of about .[
The structure of the spacecraft bus has a mass of , and must support the space telescope. It is made primarily of graphite composite material.] It was assembled in California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, assembly was completed in 2015, and then it had to be integrated with the rest of the space telescope leading up to its 2021 launch. The spacecraft bus can rotate the telescope with a pointing precision of one arcsecond, and isolates vibration down to two milliarcseconds.
Webb has two pairs of rocket engines (one pair for redundancy) to make course corrections on the way to L2 and for station keepingmaintaining the correct position in the halo orbit. Eight smaller thrusters are used for attitude control
Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc.
Controlling vehicle ...
the correct pointing of the spacecraft. The engines use hydrazine fuel ( at launch) and dinitrogen tetroxide as oxidizer ( at launch).
Servicing
JWST is not intended to be serviced in space. A crewed mission to repair or upgrade the observatory, as was done for Hubble, would not currently be possible, and according to NASA Associate Administrator Thomas Zurbuchen
Thomas Hansueli Zurbuchen (born 1968) is a Swiss-American astrophysicist. From October 2016 until the end of 2022, he was the longest continually running Associate Administrator for the Science Mission Directorate at NASA. Prior to this, he was ...
, despite best efforts, an uncrewed remote mission was found to be beyond current technology at the time JWST was designed. During the long JWST testing period, NASA officials referred to the idea of a servicing mission, but no plans were announced. Since the successful launch, NASA has stated that nevertheless limited accommodation was made to facilitate future servicing missions. These accommodations included precise guidance markers in the form of crosses on the surface of JWST, for use by remote servicing missions, as well as refillable fuel tanks, removable heat protectors, and accessible attachment points.
Software
Ilana Dashevsky and Vicki Balzano write that JWST uses modified version of JavaScript
JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
, called Nombas ScriptEase 5.00e, for its operations; it follows the ECMAScript standard and "allows for a modular design flow, where on-board scripts call lower-level scripts that are defined as functions". "The JWST science operations will be driven by ASCII (instead of binary command blocks) on-board scripts, written in a customized version of JavaScript. The script interpreter is run by the flight software, which is written in C++
C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
. The flight software operates the spacecraft and the science instruments."
Comparison with other telescopes
The desire for a large infrared space telescope traces back decades. In the United States, the Space Infrared Telescope Facility (later called the Spitzer Space Telescope) was planned while the Space Shuttle was in development, and the potential for infrared astronomy was acknowledged at that time. Unlike ground telescopes, space observatories were free from atmospheric absorption of infrared light. Space observatories opened up a whole "new sky" for astronomers.
However, infrared telescopes have a disadvantage: they need to stay extremely cold, and the longer the wavelength of infrared, the colder they need to be. If not, the background heat of the device itself overwhelms the detectors, making it effectively blind. This can be overcome by careful spacecraft design, in particular by placing the telescope in a dewar with an extremely cold substance, such as liquid helium
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity.
At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temp ...
. The coolant will slowly vaporize, limiting the lifetime of the instrument from as short as a few months to a few years at most.[ ]
In some cases, it is possible to maintain a temperature low enough through the design of the spacecraft to enable near-infrared observations without a supply of coolant, such as the extended missions of Spitzer Space Telescope and Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 201 ...
, which operated at reduced capacity after coolant depletion. Another example is Hubble's Near Infrared Camera and Multi-Object Spectrometer
The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a scientific instrument for infrared astronomy, installed on the Hubble Space Telescope (HST), operating from 1997 to 1999, and from 2002 to 2008. Images produced by NICMOS contain ...
(NICMOS) instrument, which started out using a block of nitrogen ice that depleted after a couple of years, but was then replaced during the STS-109
STS-109 (SM3B) was a Space Shuttle mission that launched from the Kennedy Space Center on 1 March 2002. It was the 108th mission of the Space Shuttle program, the 27th flight of the orbiter '' Columbia'' and the fourth servicing of the Hubble ...
servicing mission with a cryocooler
A refrigerator designed to reach cryogenic temperatures (below ) is often called a cryocooler. The term is most often used for smaller systems, typically table-top size, with input powers less than about 20 kW. Some can have input powers as l ...
that worked continuously. The James Webb Space Telescope is designed to cool itself without a dewar, using a combination of sunshields and radiators, with the mid-infrared instrument using an additional cryocooler.
JWST's delays and cost increases have been compared to those of its predecessor, the 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 vers ...
. When Hubble formally started in 1972, it had an estimated development cost of US$300 million (or about US$1 billion in 2006 constant dollars), but by the time it was sent into orbit in 1990, the cost was about four times that. In addition, new instruments and servicing missions increased the cost to at least US$9 billion by 2006.
Development history
Background (development to 2003)
Discussions of a Hubble follow-on started in the 1980s, but serious planning began in the early 1990s. The ''Hi-Z'' telescope concept was developed between 1989 and 1994: a fully baffled aperture infrared telescope that would recede to an orbit at 3 Astronomical unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits ...
(AU). This distant orbit would have benefited from reduced light noise from zodiacal dust. Other early plans called for a NEXUS precursor telescope mission.[ ]
Correcting the flawed optics of the Hubble Space Telescope in its first years played a significant role in the birth of the JWST. In 1993, NASA conducted STS-61
STS-61 was the first NASA Hubble Space Telescope servicing mission, and the fifth flight of the Space Shuttle ''Endeavour''. The mission launched on 2 December 1993 from Kennedy Space Center (KSC) in Florida. The mission restored the spacebor ...
, the Space Shuttle mission that replaced HST's camera and a installed a retrofit for its imaging spectrograph to compensate for the spherical aberration in its primary mirror
A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Description
The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
.
The HST & Beyond Committee was formed in 1994 "to study possible missions and programs for optical-ultraviolet astronomy in space for the first decades of the 21st century." Emboldened by HST's success, its 1996 report explored the concept of a larger and much colder, infrared-sensitive telescope that could reach back in cosmic time to the birth of the first galaxies. This high-priority science goal was beyond the HST's capability because, as a warm telescope, it is blinded by infrared emission from its own optical system. In addition to recommendations to extend the HST mission to 2005 and to develop technologies for finding planets around other stars, NASA embraced the chief recommendation of HST & Beyond for a large, cold space telescope (radiatively cooled far below 0 °C), and began the planning process for the future JWST.
Preparation for the 2000 Astronomy and Astrophysics Decadal Survey
The Astronomy and Astrophysics Decadal Survey is a review of astronomy and astrophysics literature produced approximately every ten years by the National Research Council of the National Academy of Sciences in the United States. The report surve ...
(a literature review produced by the United States National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrel ...
that includes identifying research priorities and making recommendations for the upcoming decade) included further development of the scientific program for what became known as the Next Generation Space Telescope,[Stockman, H. S. (June 1997). "The Next Generation Space Telescope. Visiting a time when galaxies were young". Space Telescope Science Institute, Baltimore, Maryland. The Association of Universities for Research in Astronomy, Washington, D.C.] and advancements in relevant technologies by NASA. As it matured, studying the birth of galaxies in the young universe, and searching for planets around other starsthe prime goals coalesced as "Origins" by HST & Beyond became prominent.
As hoped, the NGST received the highest ranking in the 2000 Decadal Survey.
An administrator of NASA
The Administrator of the National Aeronautics and Space Administration is the highest-ranking official of NASA, the national space agency of the United States. The administrator is NASA's chief decision maker, responsible for providing clarity to ...
, Dan Goldin, coined the phrase " faster, better, cheaper", and opted for the next big paradigm shift for astronomy, namely, breaking the barrier of a single mirror. That meant going from "eliminate moving parts" to "learn to live with moving parts" (i.e. segmented optics). With the goal to reduce mass density tenfold, silicon carbide
Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal s ...
with a very thin layer of glass on top was first looked at, but beryllium
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...
was selected at the end.
The mid-1990s era of "faster, better, cheaper" produced the NGST concept, with an aperture to be flown to , roughly estimated to cost US$500 million. In 1997, NASA worked with the Goddard Space Flight Center, Ball Aerospace & Technologies
Ball Aerospace & Technologies Corp. is an American manufacturer of spacecraft, components and instruments for national defense, civil space and commercial space applications. The company is a wholly owned subsidiary of Ball Corporation (NYSE: BAL ...
, and TRW to conduct technical requirement and cost studies of the three different concepts, and in 1999 selected Lockheed Martin and TRW for preliminary concept studies. Launch was at that time planned for 2007, but the launch date was pushed back many times (see table further down).
In 2002, the project was renamed after NASA's second administrator (1961–1968), James E. Webb
James Edwin Webb (October 7, 1906 – March 27, 1992) was an American government official who served as Undersecretary of State from 1949 to 1952. He was the second Administrator of NASA from February 14, 1961, to October 7, 1968. Webb led NAS ...
(1906–1992). Webb led the agency during the Apollo program and established scientific research as a core NASA activity.[ ]
In 2003, NASA awarded TRW the US$824.8 million prime contract for JWST. The design called for a de-scoped primary mirror and a launch date of 2010. Later that year, TRW was acquired by Northrop Grumman
Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military techn ...
in a hostile bid and became Northrop Grumman Space Technology.
Early development and replanning (2003–2007)
Development was managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, with John C. Mather
John Cromwell Mather (born August 7, 1946, Roanoke, Virginia) is an American astrophysicist, cosmologist and Nobel Prize in Physics laureate for his work on the Cosmic Background Explorer Satellite (COBE) with George Smoot.
This work helped ...
as its project scientist. The primary contractor was Northrop Grumman Aerospace Systems, responsible for developing and building the spacecraft element, which included the satellite bus
A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held.
Bus-derived satellites are opposed to specially produced satellites. Bus- ...
, sunshield, Deployable Tower Assembly (DTA) which connects the Optical Telescope Element
Optical Telescope Element (OTE) is a sub-section of the James Webb Space Telescope, a large infrared space telescope launched on , consisting of its main mirror, secondary mirrors, the framework and controls to support the mirrors, and variou ...
to the spacecraft bus, and the Mid Boom Assembly (MBA) which helps to deploy the large sunshields on orbit, while Ball Aerospace & Technologies
Ball Aerospace & Technologies Corp. is an American manufacturer of spacecraft, components and instruments for national defense, civil space and commercial space applications. The company is a wholly owned subsidiary of Ball Corporation (NYSE: BAL ...
has been subcontracted to develop and build the OTE itself, and the Integrated Science Instrument Module
Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope, a large international infrared space telescope launched on . ISIM is the heart of the JWST, and holds the main science payload which includes four scien ...
(ISIM).[ ]
Cost growth revealed in spring 2005 led to an August 2005 re-planning. The primary technical outcomes of the re-planning were significant changes in the integration and test plans, a 22-month launch delay (from 2011 to 2013), and elimination of system-level testing for observatory modes at wavelength shorter than 1.7 μm. Other major features of the observatory were unchanged. Following the re-planning, the project was independently reviewed in April 2006.
In the 2005 re-plan, the life-cycle cost of the project was estimated at US$4.5 billion. This comprised approximately US$3.5 billion for design, development, launch and commissioning, and approximately US$1.0 billion for ten years of operations.[ ] The ESA agreed in 2004 to contributing about €300 million, including the launch. The Canadian Space Agency pledged CA$39 million in 2007 and in 2012 delivered its contributions in equipment to point the telescope and detect atmospheric conditions on distant planets.
Detailed design and construction (2007–2021)
In January 2007, nine of the ten technology development items in the project successfully passed a Non-Advocate Review. These technologies were deemed sufficiently mature to retire significant risks in the project. The remaining technology development item (the MIRI
)
, subdivision_type = Country
, subdivision_name =
, subdivision_type1 = State
, subdivision_name1 =
, subdivision_type2 = Division
, subdivision_name2 ...
cryocooler) completed its technology maturation milestone in April 2007. This technology review represented the beginning step in the process that ultimately moved the project into its detailed design phase (Phase C). By May 2007, costs were still on target. In March 2008, the project successfully completed its Preliminary Design Review (PDR). In April 2008, the project passed the Non-Advocate Review. Other passed reviews include the Integrated Science Instrument Module
Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope, a large international infrared space telescope launched on . ISIM is the heart of the JWST, and holds the main science payload which includes four scien ...
review in March 2009, the Optical Telescope Element
Optical Telescope Element (OTE) is a sub-section of the James Webb Space Telescope, a large infrared space telescope launched on , consisting of its main mirror, secondary mirrors, the framework and controls to support the mirrors, and variou ...
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 can meet all science and engineering requirements for its mission. The MCDR encompassed all previous design reviews. The project schedule underwent review during the months following the MCDR, in a process called the Independent Comprehensive Review Panel, which led to a re-plan of the mission aiming for a 2015 launch, but as late as 2018. By 2010, cost over-runs were impacting other projects, though JWST itself remained on schedule.
By 2011, the JWST project was in the final design and fabrication phase (Phase C).
Assembly of the hexagonal segments of the primary mirror, which was done via robotic arm, began in November 2015 and was completed on 3 February 2016. The secondary mirror was installed on 3 March 2016. Final construction of the Webb telescope was completed in November 2016, after which extensive testing procedures began.
In March 2018, NASA delayed JWST's launch an additional 2 years to May 2020 after the telescope's sunshield ripped during a practice deployment and the sunshield's cables did not sufficiently tighten. In June 2018, NASA delayed the launch by an additional 10 months to March 2021, based on the assessment of the independent review board convened after the failed March 2018 test deployment.[ ] The review identified that JWST launch and deployment had 344 potential single-point failure
A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software appl ...
s – tasks that had no alternative or means of recovery if unsuccessful, and therefore had to succeed for the telescope to work. In August 2019, the mechanical integration of the telescope was completed, something that was scheduled to be done 12 years before in 2007.
After construction was completed, JWST underwent final tests at a Northrop Grumman factory in Redondo Beach, California. A ship carrying the telescope left California on 26 September 2021, passed through the Panama Canal
The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a condui ...
, and arrived in French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
on 12 October 2021.
Cost and schedule issues
NASA's lifetime cost for the project is expected to be US$9.7 billion, of which US$8.8 billion was spent on spacecraft design and development and US$861 million is planned to support five years of mission operations. Representatives from ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (120 ...
and CSA
CSA may refer to:
Arts and media
* Canadian Screen Awards, annual awards given by the Academy of Canadian Cinema & Television
* Commission on Superhuman Activities, a fictional American government agency in Marvel Comics
* Crime Syndicate of Amer ...
stated their project contributions amount to approximately €700 million and CA$200 million, respectively.
A study in 1984 by the Space Science Board estimated that to build a next-generation infrared observatory in orbit would cost US$4 billion (US$7B in 2006 dollars, or $10B in 2020 dollars). While this came close to the final cost of JWST, the first NASA design considered in the late 1990s was more modest, aiming for a $1 billion price tag over 10 years of construction. Over time this design expanded, added funding for contingencies, and had scheduling delays.
By 2008, when the project entered preliminary design review and was formally confirmed for construction, over US$1 billion had already been spent on developing the telescope, and the total budget was estimated at about US$5 billion (equivalent to $ billion in ). In summer 2010, the mission passed its Critical Design Review (CDR) with excellent grades on all technical matters, but schedule and cost slips at that time prompted Maryland U.S. Senator Barbara Mikulski
Barbara Ann Mikulski ( ; born July 20, 1936) is an American politician and social worker who served as a United States senator from Maryland from 1987 to 2017. A member of the Democratic Party, she also served in the United States House of Repr ...
to call for external review of the project. The Independent Comprehensive Review Panel (ICRP) chaired by J. Casani (JPL) found that the earliest possible launch date was in late 2015 at an extra cost of US$1.5 billion (for a total of US$6.5 billion). 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.[ ]
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 US$1.9 billion from NASA's overall budget, of which roughly one quarter was for JWST. US$3 billion had been spent and 75% of its hardware was in production. This budget proposal was approved by subcommittee vote the following day. The committee charged that the project was "billions of dollars over budget and plagued by poor management". In response, the American Astronomical Society issued a statement in support of JWST, as did Senator Mikulski. A number of editorials supporting JWST appeared in the international press during 2011 as well. In November 2011, Congress reversed plans to cancel JWST and instead capped additional funding to complete the project at US$8 billion.
While similar issues had affected other major NASA projects such as the Hubble telescope, some scientists expressed concerns about growing costs and schedule delays for the Webb telescope, worrying that its budget might be competing with those of other space science programs. A 2010 ''Nature'' article described JWST as "the telescope that ate astronomy". NASA continued to defend the budget and timeline of the program to Congress.
In 2018, Gregory L. Robinson
Gregory L. Robinson is an American engineer and the former director of the James Webb Space Telescope Program at NASA.
Early life
Robinson was the 9th of 11 children born to tobacco sharecroppers in rural Virginia. He attended a segregated ...
was appointed as the new director of the Webb program. Robinson was credited with raising the program's schedule efficiency (how many measures were completed on time) from 50% to 95%. For his role in improving the performance of the Webb program, Robinsons's supervisor, Thomas Zurbuchen
Thomas Hansueli Zurbuchen (born 1968) is a Swiss-American astrophysicist. From October 2016 until the end of 2022, he was the longest continually running Associate Administrator for the Science Mission Directorate at NASA. Prior to this, he was ...
, called him "the most effective leader of a mission I have ever seen in the history of NASA." In July 2022, after Webb's commissioning process was complete and it began transmitting its first data, Robinson retired following a 33-year career at NASA.
On 27 March 2018, NASA pushed back the launch to May 2020 or later, with a final cost estimate to come after a new launch window was determined with the European Space Agency (ESA).[ ] In 2019, its mission cost cap was increased by US$800 million. After launch windows were paused in 2020 due to the COVID-19 pandemic, JWST was finally launched at the end of 2021, with a total budget of just under US$10 billion.
Partnership
NASA, ESA and CSA have collaborated on the telescope since 1996. ESA's participation in construction and launch was approved by its members in 2003 and an agreement was signed between ESA and NASA in 2007. In exchange for full partnership, representation and access to the observatory for its astronomers, ESA is providing the NIRSpec instrument, the Optical Bench Assembly of the MIRI instrument, an Ariane 5 ECA launcher, and manpower to support operations. The CSA provided the Fine Guidance Sensor and the Near-Infrared Imager Slitless Spectrograph and manpower to support operations.
Several thousand scientists, engineers, and technicians spanning 15 countries have contributed to the build, test and integration of the JWST. A total of 258 companies, government agencies, and academic institutions participated in the pre-launch project; 142 from the United States, 104 from 12 European countries (including 21 from the U.K., 16 from France, 12 from Germany and 7 international["Meet the team: Partners and Contributors"](_blank)
. official NASA website of James Webb Space Telescope), and 12 from Canada. Other countries as NASA partners, such as Australia, were involved in post-launch operation.
Participating countries:
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Controversy over name
In 2002, NASA administrator (2001–2004) Sean O'Keefe
Sean Charles O'Keefe (born January 27, 1956) is a university professor at Syracuse University Maxwell School, former chairman of Airbus Group, Inc., former Secretary of the Navy, former Administrator of NASA, and former chancellor of Louisiana ...
made the decision to name the telescope after James E. Webb
James Edwin Webb (October 7, 1906 – March 27, 1992) was an American government official who served as Undersecretary of State from 1949 to 1952. He was the second Administrator of NASA from February 14, 1961, to October 7, 1968. Webb led NAS ...
, the administrator of NASA from 1961 to 1968 during the Mercury, Gemini
Gemini may refer to:
Space
* Gemini (constellation), one of the constellations of the zodiac
** Gemini in Chinese astronomy
* Project Gemini, the second U.S. crewed spaceflight program
* Gemini Observatory, consisting of telescopes in the Norther ...
, and much of the Apollo programs.
In 2015, concerns were raised around Webb's possible role in the lavender scare, the mid-20th-century persecution by the U.S. government targeting homosexuals
Homosexuality is romantic attraction, sexual attraction, or sexual behavior between members of the same sex or gender. As a sexual orientation, homosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" to pe ...
in federal employment. In 2022, NASA released a report of an investigation and accompanying evidence, based on an examination of more than 50,000 documents. The report found there was no evidence of wrongdoing by Webb either in his time in the State Department or at NASA. As a result, NASA did not rename the telescope.
Mission goals
The James Webb Space Telescope has four key goals:
* to search for light from the first stars and galaxies that formed in the universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
after the Big Bang
* to study 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 gen ...
* to understand star formation and planet formation
The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbitin ...
* to study planetary systems and the origins of life
In biology, abiogenesis (from a- 'not' + Greek bios 'life' + genesis 'origin') or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothes ...
These goals can be accomplished more effectively by observation in near-infrared light rather than light in the visible part of the spectrum. For this reason, JWST's instruments will not measure visible or ultraviolet light like the Hubble Telescope, but will have a much greater capacity to perform infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in betw ...
. JWST will be sensitive to a range of wavelengths from 0.6 to 28 μm (corresponding respectively to orange light and deep infrared radiation at about ).
JWST may be used to gather information on the dimming light of star KIC 8462852
Tabby's Star (also known as Boyajian's Star and WTF Star, and designated KIC 8462852 in the Kepler Input Catalog) is an F-type main-sequence star in the constellation Cygnus (constellation), Cygnus approximately from Earth. Unusual ligh ...
, which was discovered in 2015, and has some abnormal light-curve properties.
Additionally, it will be able to tell if an exoplanet has methane in its atmosphere, allowing astronomers to determine whether or not the methane is a biosignature.
Orbit design
JWST orbits the Sun near the second Lagrange point () of the Sun–Earth system, which is farther from the Sun than the Earth's orbit, and about four times farther than the Moon's orbit. Normally an object circling the Sun farther out than Earth would take longer than one year to complete its orbit. But near the point, the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time that it takes the Earth. Staying close to Earth allows data rates to be much faster for a given size of antenna.
The telescope circles about the Sun–Earth point in a halo orbit, which is inclined with respect to the ecliptic
The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agains ...
, has a radius varying between about and , and takes about half a year to complete. Since is just an equilibrium point with no gravitational pull, a halo orbit is not an orbit in the usual sense: the spacecraft is actually in orbit around the Sun, and the halo orbit can be thought of as controlled drifting to remain in the vicinity of the point. This requires some station-keeping: around per year from the total ∆''v'' budget of . Two sets of thrusters constitute the observatory's propulsion system. Because the thrusters are located solely on the Sun-facing side of the observatory, all station-keeping operations are designed to slightly undershoot the required amount of thrust in order to avoid pushing the JWST beyond the semi-stable point, a situation which would be unrecoverable. Randy Kimble, the Integration and Test Project Scientist for the James Webb Space Telescope, compared the precise station-keeping of the JWST to "Sisyphus
In Greek mythology, Sisyphus or Sisyphos (; Ancient Greek: Σίσυφος ''Sísyphos'') was the founder and king of Ephyra (now known as Corinth). Hades punished him for cheating death twice by forcing him to roll an immense boulder up a hill ...
..rolling this rock up the gentle slope near the top of the hill – we never want it to roll over the crest and get away from him".
Infrared astronomy
JWST is the formal successor to the Hubble Space Telescope (HST), and since its primary emphasis is on infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in betw ...
, it is also a successor to the Spitzer Space Telescope. JWST will far surpass both those telescopes, being able to see many more and much older stars and galaxies.[Howard, Rick]
"James Webb Space Telescope (JWST)"
, ''nasa.gov'', 6 March 2012 Observing in the infrared spectrum is a key technique for achieving this, because of cosmological redshift
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving ...
, and because it better penetrates obscuring dust and gas. This allows observation of dimmer, cooler objects. Since water vapor and carbon dioxide in the Earth's atmosphere strongly absorbs most infrared, ground-based infrared astronomy is limited to narrow wavelength ranges where the atmosphere absorbs less strongly. Additionally, the atmosphere itself radiates in the infrared spectrum, often overwhelming light from the object being observed. This makes a space telescope preferable for infrared observation.
The more distant an object is, the younger it appears; its light has taken longer to reach human observers. Because the universe is expanding, as the light travels it becomes red-shifted, and objects at extreme distances are therefore easier to see if viewed in the infrared. JWST's infrared capabilities are expected to let it see back in time to the first galaxies forming just a few hundred million years after the Big Bang.[ ]
Infrared radiation can pass more freely through regions of cosmic dust
Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...
that scatter visible light. Observations in infrared allow the study of objects and regions of space which would be obscured by gas and dust in the visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' or simply light. A typical human eye will respond to wa ...
,[ ] such as the molecular cloud
A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydroge ...
s where stars are born, the circumstellar disks
A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the re ...
that give rise to planets, and the cores of active galaxies
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...
.
Relatively cool objects (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, brown dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
s, planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s both in our own and other solar systems, comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s, and Kuiper belt objects
The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...
that will be observed with the Mid-Infrared Instrument (MIRI).[
Some of the missions in infrared astronomy that impacted JWST development were ]Spitzer
Spitzer is a surname. Notable people with the surname include:
* Andre Spitzer (1945–1972), Israeli fencing coach and victim of the Munich massacre
* Bernard Spitzer (1924–2014), American real estate developer and philanthropist, father of Eli ...
and the Wilkinson Microwave Anisotropy Probe (WMAP).[ ] Spitzer showed the importance of mid-infrared, which is helpful for tasks such as observing dust disks around stars. Also, the WMAP probe showed the universe was "lit up" at redshift 17, further underscoring the importance of the mid-infrared. Both these missions were launched in the early 2000s, in time to influence JWST development.
Ground support and operations
The Space Telescope Science Institute
The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for the ...
(STScI), in Baltimore, Maryland
Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
, on the Homewood Campus of Johns Hopkins University The Homewood Campus is the main academic and administrative center of the Johns Hopkins University. It is located at 3400 North Charles Street in Baltimore, Maryland. It houses the two major undergraduate schools: the Zanvyl Krieger School of Arts a ...
, was selected in 2003 as the Science and Operations Center (S&OC) for JWST with an initial budget of US$162.2 million intended to support operations through the first year after launch. In this capacity, STScI was to be responsible for the scientific operation of the telescope and delivery of data products to the astronomical community. Data was to be transmitted from JWST to the ground via the NASA Deep Space Network
The NASA Deep Space Network (DSN) is a worldwide network of American spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA's interplanetary ...
, 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 is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer revie ...
the submitted proposals to select the projects 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.
The bandwidth and digital throughput of the satellite is designed to operate at 458 gigabits of data per day for the length of the mission (equivalent to a sustained rate of 5.42 Mbps
In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mult ...
). Most of the data processing on the telescope is done by conventional single-board computers. The digitization of the analog data from the instruments is performed by the custom SIDECAR ASIC (System for Image Digitization, Enhancement, Control And Retrieval Application Specific Integrated Circuit
An application-specific integrated circuit (ASIC ) is an integrated circuit (IC) chip customized for a particular use, rather than intended for general-purpose use, such as a chip designed to run in a digital voice recorder or a high-effici ...
). NASA stated that the SIDECAR ASIC will include all the functions of a instrument box in a package and consume only 11 milliwatts of power.[ ] Since this conversion must be done close to the detectors, on the cold side of the telescope, the low power dissipation is crucial for maintaining the low temperature required for optimal operation of JWST.
Micrometeoroid strike
The C3 mirror segment suffered a micrometeoroid strike from a large dust mote-sized particle between 23 and 25 May, the fifth and largest strike since launch, reported 8 June 2022, which required engineers to compensate for the strike using a mirror actuator
A mirror or looking glass is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the im ...
. Despite the strike, a NASA characterization report states "all JWST observing modes have been reviewed and confirmed to be ready for science use" as of July 10, 2022.
From launch through commissioning
Launch
The launch (designated Ariane flight VA256
Ariane flight VA256 was an Ariane 5 rocket flight that launched the James Webb Space Telescope into space on 25 December 2021. It was 2021's final Ariane flight, its most valuable payload to date, and the Ariane mission. The launch was describ ...
) took place as scheduled at 12:20 UTC on 25 December 2021 on an Ariane 5 rocket that lifted off from the Guiana Space Centre
The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...
in French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
. The telescope was confirmed to be receiving power, starting a two-week deployment phase of its parts and traveling to its target destination. The telescope was released from the upper stage 27 minutes 7 seconds after launch, beginning a 30-day adjustment to place the telescope in a Lissajous orbit around the Lagrange point.
The telescope was launched with slightly less speed than needed to reach its final orbit, and slowed down as it travelled away from Earth, in order to reach L2 with only the velocity needed to enter its orbit there. The telescope reached L2 on 24 January 2022. The flight included three planned course corrections to adjust its speed and direction. This is because the observatory could recover from underthrust (going too slowly), but could not recover from overthrust (going too fast) – to protect highly temperature-sensitive instruments, the sunshield must remain between telescope and Sun, so the spacecraft could not turn around or use its thrusters to slow down.
File:Ariane 5 with James Webb Space Telescope Prelaunch (NHQ202112230012).jpg, alt=JWST and Ariane 5 Rollout, Ariane 5 and JWST at the ELA-3
ELA-3 (french: Ensemble de Lancement Ariane 3, lit=Ariane Launch Complex 3), is a launch pad and associated facilities at the Centre Spatial Guyanais in French Guiana. ELA-3 is operated by Arianespace as part of the expendable launch system f ...
launch pad
File:James Webb Space Telescope Launch (NHQ202112250010).jpg, alt=Ariane 5 containing JWST lifting-off from the launch pad, Ariane 5 containing JWST lifting-off from the launch pad
File:James Webb Space Telescope Launch.jpg, alt=Ariane 5 moments after lift-off, Ariane 5 containing JWST moments after lift-off
File:JWST as seen from the ESC-D Cryotechnic upper stage.png, alt=JWST as seen from the ESC-D Cryotechnic upper stage, JWST as seen from the ESC-D Cryotechnic upper stage shortly after separation, approximately 29 minutes after launch. Part of the Earth with the Gulf of Aden is visible in the background of the image.[Camera on ESC-D Cryotechnic upper stag]
(25 Dec 2021) view of newly separated JWST, as seen from the ESC-D Cryotechnic upper stage
Transit and structural deployment
JWST was released from the rocket upper stage 27 minutes after a flawless launch. Starting 31 minutes after launch, and continuing for about 13 days, JWST began the process of deploying its solar array, antenna, sunshield, and mirrors. Nearly all deployment actions are commanded by the Space Telescope Science Institute in Baltimore
Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
, except for two early automatic steps, solar panel unfolding and communication antenna deployment. The mission was designed to give ground controllers flexibility to change or modify the deployment sequence in case of problems.
At 7:50p.m. EST on 25 December 2021, about 12 hours after launch, the telescope's pair of primary rockets began firing for 65 minutes to make the first of three planned mid-course corrections. On day two, the high gain communication antenna deployed automatically.
On 27 December 2021, at 60 hours after launch, Webb's rockets fired for nine minutes and 27 seconds to make the second of three mid-course corrections for the telescope to arrive at its L2 destination. On 28 December 2021, three days after launch, mission controllers began the multi-day deployment of Webb's all-important sunshield. On 30 December 2021, controllers successfully completed two more steps in unpacking the observatory. First, commands deployed the aft "momentum flap", a device that provides balance against solar pressure on the sunshield, saving fuel by reducing the need for thruster firing to maintain Webb's orientation.
On 31 December 2021, the ground team extended the two telescoping "mid booms" from the left and right sides of the observatory. The left side deployed in 3 hours and 19 minutes; the right side took 3 hours and 42 minutes. Commands to separate and tension the membranes followed between 3 and 4 January and were successful. On 5 January 2022, mission control successfully deployed the telescope's secondary mirror, which locked itself into place to a tolerance of about one and a half millimeters.
The last step of structural deployment was to unfold the wings of the primary mirror. Each panel consists of three primary mirror segments and had to be folded to allow the space telescope to be installed in the fairing of the Ariane rocket for the launch of the telescope. On 7 January 2022, NASA deployed and locked in place the port-side wing, and on 8 January, the starboard-side mirror wing. This successfully completed the structural deployment of the observatory.
On 24 January 2022, at 2:00p.m. EST, nearly a month after launch, a third and final course correction took place, inserting JWST into its planned halo orbit around the Sun–Earth L2 point.
The MIRI instrument has four observing modes—imaging, low-resolution spectroscopy, medium-resolution spectroscopy and coronagraphic imaging. “ On Aug. 24, a mechanism that supports medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction during setup for a science observation. This mechanism is a grating wheel that allows scientists to select between short, medium, and longer wavelengths when making observations using the MRS mode,” said NASA in a press statement.
Commissioning and testing
On 12 January 2022, while still in transit, mirror alignment began. The primary mirror segments and secondary mirror were moved away from their protective launch positions. This took about 10 days, because the 132 actuator motors are designed to fine-tune the mirror positions at microscopic accuracy (10 nanometer increments) and must each move over 1.2 million increments (12.5 mm) during initial alignment.
Mirror alignment requires each of the 18 mirror segments, and the secondary mirror, to be positioned to within 50 nanometers. NASA compares the required accuracy by analogy: "If the Webb primary mirror were the size of the United States, each irrorsegment would be the size of Texas, and the team would need to line the height of those Texas-sized segments up with each other to an accuracy of about 1.5 inches".[ ]
File:JWST Segment Image Identification.gif, Segment image identification. 18 mirror segments are moved to determine which segment creates which segment image. After matching the mirror segments to their respective images, the mirrors are tilted to bring all the images near a common point for further analysis.
File:JWST Segment Alignment.gif, Segment alignment begins by defocusing the segment images by moving the secondary mirror slightly. Mathematical analysis, called phase retrieval, is applied to the defocused images to determine the precise positioning errors of the segments. Adjustments of the segments then result in 18 well-corrected "telescopes". However, the segments still do not work together as a single mirror.
File:JWST Image Stacking.gif, Image stacking. To put all of the light in a single place, each segment image must be stacked on top of one another. In the image stacking step, the individual segment images are moved so that they fall precisely at the center of the field to produce one unified image. This process prepares the telescope for coarse phasing.
File:JWST Telescope Alignment Over Instrument Fields of View.gif, Telescope alignment over instrument fields of view. After fine phasing, the telescope will be well aligned at one place in the NIRCam field of view. Now the alignment must be extended to the rest of the instruments.
Mirror alignment was a complex operation split into seven phases, that had been repeatedly rehearsed using a 1:6 scale model of the telescope. Once the mirrors reached , NIRCam
NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other wor ...
targeted the 6th magnitude star HD 84406 in Ursa Major
Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...
. To do this, NIRCam took 1560 images of the sky and used these wide-ranging images to determine where in the sky each segment of the main mirror initially pointed. At first, the individual primary mirror segments were greatly misaligned, so the image contained 18 separate, blurry, images of the star field, each containing an image of the target star. The 18 images of HD 84406 are matched to their respective mirror segments, and the 18 segments are brought into approximate alignment centered on the star ("Segment Image Identification"). Each segment was then individually corrected of its major focusing errors, using a technique called phase retrieval
Phase retrieval is the process of algorithmically finding solutions to the phase problem. Given a complex signal F(k), of amplitude , F (k), , and phase \psi(k):
::F(k) = , F(k), e^ =\int_^ f(x)\ e^\,dx
where ''x'' is an ''M''-dimensional spatia ...
, resulting in 18 separate good quality images from the 18 mirror segments ("Segment Alignment"). The 18 images from each segment, were then moved so they precisely overlap to create a single image ("Image Stacking").
With the mirrors now positioned for almost correct images, they had to be fine tuned to their operational accuracy of 50 nanometers, less than one wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...
of the light that will be detected. A technique called ''dispersed fringe sensing'' was used to compare images from 20 pairings of mirrors, allowing most of the errors to be corrected ("Coarse Phasing"), and then introduced light defocus to each segment's image, allowing detection and correction of almost all remaining errors ("Fine Phasing"). These two processes were repeated three times, and Fine Phasing will be routinely checked throughout the telescope's operation. After three rounds of Coarse and Fine Phasing, the telescope was well aligned at one place in the NIRCam field of view. Measurements will be made at various points in the captured image, across all instruments, and corrections calculated from the detected variations in intensity, giving a well-aligned outcome across all instruments ("Telescope Alignment Over Instrument Fields of View"). Finally, a last round of Fine Phasing and checks of image quality on all instruments was performed, to ensure that any small residual errors remaining from the previous steps, were corrected ("Iterate Alignment for Final Correction"). The telescope's mirror segments were then aligned and able to capture precise focused images.
In preparation for alignment, NASA announced at 19:28 UTC on 3 February 2022, that NIRCam had detected the telescope's first photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they a ...
s (although not yet complete images). On 11 February 2022, NASA announced the telescope had almost completed phase 1 of alignment, with every segment of its primary mirror having located and imaged the target star HD 84406, and all segments brought into approximate alignment. Phase 1 alignment was completed on 18 February 2022, and a week later, phases 2 and 3 were also completed.[Webb Mirror Alignment Continues Successfully](_blank)
– NASA blog This meant the 18 segments were working in unison, however until all 7 phases are complete, the segments were still acting as 18 smaller telescopes rather than one larger one. At the same time as the primary mirror was being commissioned, hundreds of other instrument commissioning and calibration tasks were also ongoing.[To Find the First Galaxies, Webb Pays Attention to Detail and Theory](_blank)
– NASA
File:JWST - First images of HD 84406 (segments marked).png, Phase 1 interim image, annotated with the related mirror segments that took each image
File:JWST - Images of HD 84406 after phase 1 alignment (segments marked).png, Phase 1 annotated completion image of HD 84406
File:JWST commissioning - HD 84406 animated segment alignment.gif, Phase 2 completion, showing "before and after" effects of segment alignment
File:JWST commissioning - HD 84406 after image stacking.jpg, Phase 3 completion, showing 18 segments "stacked" as a single image of HD 84406
File:JWST Telescope alignment evaluation image labeled.jpg, Star 2MASS J17554042+6551277 captured by NIRCam instrument
File:JWST Nircam alignment selfie labeled.jpg, A "selfie" taken by the NIRCam during the alignment process
File:MIRI test image of the Large Magellanic Cloud - Spitzer vs webb LMC.png, Image comparison between "old" Spitzer
Spitzer is a surname. Notable people with the surname include:
* Andre Spitzer (1945–1972), Israeli fencing coach and victim of the Munich massacre
* Bernard Spitzer (1924–2014), American real estate developer and philanthropist, father of Eli ...
and new JWST
File:Webb in Full Focus.jpg, Alignment of the NASA/ESA/CSA James Webb Space Telescope's sensors.
File:Fine Guidance Sensor Test Image.jpg, Webb’s Fine Guidance Sensor (FGS).
Allocation of observation time
JWST observing time is allocated through a General Observers (GO) program, a Guaranteed Time Observations (GTO) program, and a Director's Discretionary Early Release Science (DD-ERS) program. The GTO program provides guaranteed observing time for scientists who developed hardware and software components for the observatory. The GO program provides all astronomers the opportunity to apply for observing time and will represent the bulk of the observing time. GO programs are selected through peer review by a Time Allocation Committee (TAC), similar to the proposal review process used for the Hubble Space Telescope.
Early Release Science program
In November 2017, the Space Telescope Science Institute announced the selection of 13 Director's Discretionary Early Release Science (DD-ERS) programs, chosen through a competitive proposal process. The observations for these programs were to be obtained during the first five months of JWST science operations after the end of the commissioning period. A total of 460 hours of observing time was awarded to these 13 programs, which span science topics including the Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
, exoplanets, stars and star formation, nearby and distant galaxies, gravitational lens
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...
es, and quasars. These 13 ERS programs were to use a total of 242.8 hours of observing time on the telescope (not including JWST observing overheads and slew time).
General Observer Program
For GO Cycle 1 there were 6,000 hours of observation time available to allocate, and 1,173 proposals were submitted requesting a total of 24,500 hours of observation time. Selection of Cycle 1 GO programs was announced on 30 March 2021, with 266 programs approved. These include 13 large programs and treasury programs producing data for public access. JWST science observations are nominally scheduled in weekly increments, observation plan for every week is published on Mondays by the Space Telescope Science Institute.
Scientific results
The first full-color images and spectroscopic data were released on 12 July 2022, which also marked the official beginning of Webb's general science operations; President Joe Biden revealed the first image, '' Webb's First Deep Field'', on 11 July 2022. NASA announced the list of observations targeted for release:
* Carina Nebula young, star-forming region called NGC 3324
NGC 3324 is an open cluster in the southern constellation Carina, located northwest of the Carina Nebula at a distance of from Earth. It is closely associated with the emission nebula , also known as . The two are often confused as a single ob ...
displaying "Cosmic Cliffs" about 8500 light-years from Earth.
* WASP-96b
WASP-96b is a gas giant exoplanet. Its mass is 0.48 times that of Jupiter. It is 0.0453 AU from the class G star WASP-96, which it orbits every 3.4 days. It is about 1,140 light-years away from Earth, in the constellation Phoenix. It was dis ...
including an analysis of atmosphere with evidence of water around a giant gas planet orbiting a distant star 1120 light-years from Earth.
* Southern Ring Nebula clouds of gas and dust expelled by a dying star 2500 light-years from Earth.
* Stephan's Quintet a visual display of five galaxies with colliding gas and dust clouds creating new stars; four central galaxies are 290 million light-years from Earth.
* SMACS J0723.3-7327 a gravitationally lensed view called ''Webb's First Deep Field'' 4.6 billion light-years from Earth, with distant galaxies as far away as 13.1 billion light-years. Sometimes abbreviated as SMACS 0723.[
On 14 July 2022, NASA presented images of Jupiter and related areas captured, for the first time, and including infrared views, by the James Webb Space Telescope.]
In a preprint released around the same time, NASA, ESA and CSA scientists stated that "almost across the board, the science performance of JWST is better than expected". The document described a series of observations during the commissioning, when the instruments captured spectra of transiting exoplanets with a precision better than 1000 ppm per data point and tracked moving objects with speeds up to 67 milliarcseconds/second, more than twice as fast as the requirement. It also obtained the spectra of hundreds of stars simultaneously in a dense field towards the Galactic Center
The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact ra ...
. Other targets described in the document:
* Moving targets: Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
(including rings and the moons Europa
Europa may refer to:
Places
* Europe
* Europa (Roman province), a province within the Diocese of Thrace
* Europa (Seville Metro), Seville, Spain; a station on the Seville Metro
* Europa City, Paris, France; a planned development
* Europa Cliff ...
, Thebe
Thebe may refer to:
* Any of several female characters in Greek mythology - see List of mythological figures named Thebe
* Thebe (moon), a moon of Jupiter
* Thebe (currency), 1/100 of a Botswana pula
* Thebe, an Amazons, Amazon
* Thebe, alternate ...
and Metis
Metis or Métis may refer to:
Ethnic groups
* Métis, recognized Indigenous communities in Canada and America whose distinct culture and language emerged after early intermarriage between First Nations peoples and early European settlers, prima ...
), asteroids 2516 Roman
Year 516 (DXVI) was a leap year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Petrus without colleague (or, less frequently, year 1269 ''Ab urbe cond ...
, 118 Peitho
Peitho (minor planet designation: 118 Peitho) is a main-belt asteroid. It is probably an S-type asteroid, suggesting a siliceous mineralogy. It was discovered by R. Luther on March 15, 1872, and named after one of the two Peithos in Greek mythol ...
, 6481 Tenzing, 1773 Rumpelstilz, 216 Kleopatra
216 Kleopatra is a large M-type asteroid with a mean diameter of and is noted for its elongate bone or dumbbell shape. It was discovered on 10 April 1880 by Austrian astronomer Johann Palisa at the Austrian Naval Pola Observatory, in what is no ...
, 2035 Stearns
2035 Stearns, provisional designation , is a bright Hungaria asteroid and sizable Mars-crosser inside the inner regions of the asteroid belt, approximately in diameter. It was discovered on 21 September 1973, by American astronomer James Gibson ...
, 4015 Wilson-Harrington and 2004 JX20
4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures.
In mathematics
Four is the smallest c ...
* NIRCam grism time-series, NIRISS SOSS and NIRSpec BOTS mode: the Jupiter-sized planet HAT-P-14b
HAT-P-14b, also known as WASP-27b, is an extrasolar planet located approximately away in the constellation of Hercules, orbiting the 10th magnitude F-type star HAT-P-14. This planet was discovered in 2010 by the HATNet Project using the tra ...
* NIRISS aperture masking interferometry (AMI): A clear detection of the very low-mass companion star AB Doradus C, which had a separation of only 0.3 arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The ...
to the primary. This observation was the first demonstration of AMI in space.
* MIRI low-resolution spectroscopy (LRS): a hot super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively.
The term "super-Earth" refers only to ...
planet L 168-9 b (TOI-134) around a bright M-dwarf star
Within two weeks of the first Webb images, several preprint papers described a wide range of early galaxies believed to date from 235 million years (z=16.7) to 280 million years after the Big Bang, far earlier than previously known. The results await peer review. On 17 August 2022, NASA released a large mosaic image of 690 individual frames taken by the Near Infrared Camera
NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other wor ...
(NIRCam) on JWST of numerous very early galaxies. Some early galaxies observed by JWST like CEERS-93316
CEERS-93316 is a candidate high-redshift galaxy, with an estimated redshift of approximately z = 16.4, corresponding to 236 million years after the Big Bang.
If confirmed, it would be one of the earliest and most distant known galaxies observe ...
, which has an estimated redshift of approximately z=16.7 corresponding to 235.8 million years after the Big Bang, are high redshift galaxy candidates.[
]
On 24 August 2022, astronomers published the first detailed scientific result for the telescope on the detection of carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
in the atmosphere of the gas giant exoplanet WASP-39b
WASP-39b, officially named Bocaprins, is a "hot Jupiter" extrasolar planet discovered in February 2011 by the Wide Angle Search for Planets, WASP project, notable for containing a substantial amount of water in its atmosphere. In addition WASP-3 ...
from transmission spectroscopy observations obtained with JWST as part of the Early Release Science program ( ERS). It was the first confirmed detection of carbon dioxide on a planet outside the Solar System.
Gallery
File:NASA’s Webb Reveals Cosmic Cliffs, Glittering Landscape of Star Birth.jpg, Cosmic Cliffs of Carina Nebula (NIRCam)
File:NASA’s Webb Reveals Cosmic Cliffs, Glittering Landscape of Star Birth - Flickr - James Webb Space Telescope.png, Carina Nebula (MIRI)
File:NASA’s Webb Captures Dying Star’s Final ‘Performance’ in Fine Detail.png, Southern Ring Nebula (NGC 3132
NGC 3132 (also known as the Eight-Burst Nebula, the Southern Ring Nebula, or Caldwell 74) is a bright and extensively studied planetary nebula in the constellation Vela. Its distance from Earth is estimated at about 613 pc. or 2,000 light-ye ...
; Left: NIRCam; Right: MIRI)
File:Webb’s First Deep Field (MIRI and NIRCam Images Side by Side).png, Webb's First Deep Field (Left: MIRI
)
, subdivision_type = Country
, subdivision_name =
, subdivision_type1 = State
, subdivision_name1 =
, subdivision_type2 = Division
, subdivision_name2 ...
; Right: NIRCam
NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other wor ...
)
File:Stephan's Quintet taken by James Webb Space Telescope.jpg, Stephan's Quintet (NIRCam/MIRI composite)
File:Stephan's Quintet as seen by JWST's NIRCAM.png, Stephan's Quintet (NIRCam)
File:Stephan’s Quintet (MIRI Imaging).png, Stephan's Quintet (MIRI)
File:Exoplanet WASP-96 b (NIRISS Transmission Spectrum) (weic2206a).jpeg, Spectrum of WASP-96b
WASP-96b is a gas giant exoplanet. Its mass is 0.48 times that of Jupiter. It is 0.0453 AU from the class G star WASP-96, which it orbits every 3.4 days. It is about 1,140 light-years away from Earth, in the constellation Phoenix. It was dis ...
Cartwheel Galaxy
The Cartwheel Galaxy (also known as ESO 350-40 or PGC 2248) is a lenticular ring galaxy about 500 million light-years away in the constellation Sculptor. It has a D25 isophotal diameter of , and a mass of about solar masses; its outer ring ...
, located about 500 million light-years away in the Sculptor constellation released 2 August 2022" mode="packed" heights="100">
File:Cartwheel Galaxy JWST NIRCam+MIRI Full Res.png, NIRCam/MIRI composite
File:Cartwheel Galaxy JWST NIRCam Full Res.png, NIRCam
File:Cartwheel Galaxy (MIRI).png, MIRI