James Webb Space Telescope

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James Webb Space Telescope

A rendering of the James Webb Space Telescope with its components fully deployed.
Mission type	Astronomy
Operator	NASA / ESA / CSA / STScI
Website	jwst.nasa.gov sci.esa.int/jwst asc-csa.gc.ca jwst.stsci.edu
Mission duration	5 years (design) 10 years (goal)
Spacecraft properties
Manufacturer	Northrop Grumman Ball Aerospace
Launch mass	6,500 kg (14,300 lb)
Dimensions	20.197 m × 14.162 m (66.26 ft × 46.46 ft) (sunshield)
Power	2,000 watts
Start of mission
Launch date	March 30, 2021 (planned)
Rocket	Ariane 5 ECA
Launch site	Kourou ELA-3
Contractor	Arianespace
Orbital parameters
Reference system	Sun–Earth L2
Regime	Halo orbit
Periapsis	374,000 km (232,000 mi)
Apoapsis	1,500,000 km (930,000 mi)
Period	6 months
Epoch	plan
Main
Type	Korsch telescope
Diameter	6.5 m (21 ft)
Focal length	131.4 m (431 ft)
Collecting area	25 m2 (270 sq ft)
Wavelengths	from 0.6 µm (orange) to 28.5 µm (mid-infrared)
Transponders
Band	S-band (TT&C support) Ka band (data acquisition)
Bandwidth	S-band up: 16 kbit/s S-band down: 40 kbit/s Ka band down: up to 28 Mbit/s

Instruments

James Webb Space Telescope insignia

The James Webb Space Telescope (JWST) is a space telescope that will be the successor to the Hubble Space Telescope. The JWST will offer unprecedented resolution and sensitivity, and will enable a broad range of investigations across the fields of astronomy and cosmology. One of its major goals is observing some of the most distant events and objects in the universe, such as the formation of the first galaxies. These types of targets are beyond the reach of current ground- and space-based instruments. Other goals include understanding the formation of stars and planets, and direct imaging of exoplanets and novas.

The JWST's primary mirror is composed of 18 hexagonal mirror segments made of gold-coated beryllium. These combine to create a mirror with a diameter of 6.5 meters (21 ft 4 in)—much larger than the Hubble's 2.4-meter (7.9 ft) mirror. Unlike the Hubble—which observes in the near ultraviolet, visible, and near infrared spectra—the JWST will observe in the long-wavelength visible light through the mid-infrared (0.6 to 27 μm) range. This will allow the JWST to observe high redshift objects that are too old and too distant for the Hubble and other earlier instruments to observe. The telescope must be kept very cold to observe in the infrared without interference, so it will be deployed in space near the Earth–Sun L₂ Lagrangian point, and a large sunshield made of five sheets of silicon- and aluminum-coated Kapton will keep JWST's mirror and four science instruments below 50 K (−220 °C; −370 °F).

The JWST is being developed by NASA—with significant contributions from the Canadian Space Agency and the European Space Agency—and is named after James E. Webb, the American government official who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program. Development began in 1996, but the project has had numerous delays and cost overruns, and underwent a major redesign during 2005. In December 2016, NASA announced that construction of the JWST was complete and that its extensive testing phase would begin. In March 2018, NASA delayed the JWST's launch after the telescope's sunshield ripped during a practice deployment. The JWST's launch was delayed again in June 2018 following recommendations from an independent review board, and is currently scheduled for March 2021.

Overview

Launch configuration of the JWST in an Ariane 5

The JWST originated in 1996 as the Next Generation Space Telescope (NGST). In 2002 it was renamed after NASA's second administrator (1961–1968) James E. Webb (1906–1992), noted for playing a key role in the Apollo program and establishing scientific research as a core NASA activity. The JWST is a project of the National Aeronautics and Space Administration, the United States space agency, with international collaboration from the European Space Agency and the Canadian Space Agency.

The telescope has an expected mass about half of Hubble Space Telescope's, but its primary mirror (a 6.5 meter diameter gold-coated beryllium reflector) will have a collecting area about five times as large (25 m² or 270 sq ft vs. 4.5 m² or 48 sq ft). The JWST is oriented toward near-infrared astronomy, but can also see orange and red visible light, as well as the mid-infrared region, depending on the instrument. The design emphasizes the near to mid-infrared for three main reasons: High-redshift objects have their visible emissions shifted into the infrared, cold objects such as debris disks and planets emit most strongly in the infrared, and this band is difficult to study from the ground or by existing space telescopes such as Hubble. Ground-based telescopes must look through the atmosphere, which is opaque in many infrared bands (see figure of atmospheric transmission). Even where the atmosphere is transparent, many of the target chemical compounds, such as water, carbon dioxide, and methane, also exist in the Earth's atmosphere, vastly complicating analysis. Existing space telescopes such as Hubble cannot study these bands since their mirrors are not cool enough (the Hubble mirror is maintained at about 15 degrees C) and hence the telescope itself radiates strongly in the infrared bands.

The JWST will operate near the Earth–Sun L₂ (Lagrange) point, approximately 930,000 mi (1,500,000 km) beyond Earth's orbit. By way of comparison, Hubble orbits 340 miles (550 km) above Earth's surface, and the Moon is roughly 250,000 miles (400,000 km) from Earth. This distance makes post-launch repair or upgrade of the JWST hardware virtually impossible. Objects near this point can orbit the Sun in synchrony with the Earth, allowing the telescope to remain at a roughly constant distance and use a single sunshield to block heat and light from the Sun and Earth. This will keep the temperature of the spacecraft below 50 K (−220 °C; −370 °F), necessary for infrared observations. The prime contractor is Northrop Grumman.

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  Three-quarter view of the top
  
  
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  Bottom (sun-facing side)
  

Sunshield protection

Test unit of the sunshield stacked and expanded at the Northrop Grumman facility in California, 2014

To make observations in the infrared spectrum, the JWST must be kept very cold (under 50 K (−220 °C; −370 °F)), otherwise infrared radiation from the telescope itself would overwhelm its instruments. Therefore, it uses a large sunshield to block light and heat from the Sun, Earth, and Moon, and its position near the Earth–Sun L₂ point keeps all three bodies on the same side of the spacecraft at all times. Its halo orbit around L₂ avoids the shadow of the Earth and Moon, maintaining a constant environment for the sunshield and solar arrays. The shielding maintains a stable temperature throughout the structures on the dark side, which is critical to maintaining precise alignment of the primary mirror segments.

The five-layer sunshield is constructed from polyimide film, with membranes coated with aluminum on one side and silicon on the other. Accidental tears of the delicate film structure during testing are one factor delaying the project.

The sunshield is designed to be folded twelve times so it will fit within the Ariane 5 rocket's 4.57 m (5 yards) × 16.19 m (17.7 yards) payload fairing. Once deployed at the L2 point, it will unfold to 21.197 m (23.18 yards) × 14.162 m (15.55 yards). The sunshield was hand-assembled at Man Tech (NeXolve) in Huntsville, Alabama, before it was delivered to Northrop Grumman in Redondo Beach, California, USA for testing.

Optics

Main mirror assembled at Goddard Spaceflight Center, May 2016

JWST's primary mirror is a 6.5-meter-diameter gold-coated beryllium reflector with a collecting area of 25 m². This is too large for existing launch vehicles, so the mirror is composed of 18 hexagonal segments, which will unfold after the telescope is launched. Image plane wavefront sensing through phase retrieval will be used to position the mirror segments in the correct location using very precise micro-motors. Subsequent to this initial configuration they will only need occasional updates every few days to retain optimal focus. This is unlike terrestrial telescopes like the Keck which continually adjust their mirror segments using active optics to overcome the effects of gravitational and wind loading, and is made possible because of the lack of environmental disturbances of a telescope in space.

JWST's optical design is a three-mirror anastigmat, which makes use of curved secondary and tertiary mirrors to deliver images that are free of optical aberrations over a wide field. In addition, there is a fast steering mirror, which can adjust its position many times per second to provide image stabilization.

Ball Aerospace & Technologies Corp. is the principal optical subcontractor for the JWST project, led by prime contractor Northrop Grumman Aerospace Systems, under a contract from the NASA Goddard Space Flight Center, in Greenbelt, Maryland. Eighteen primary mirror segments, secondary, tertiary and fine steering mirrors, plus flight spares have been fabricated and polished by Ball Aerospace based on beryllium segment blanks manufactured by several companies including Axsys, Brush Wellman, and Tinsley Laboratories.

The final segment of the primary mirror was installed on February 3, 2016, and the secondary mirror was installed on March 3, 2016.

Scientific instruments

The Integrated Science Instrument Module (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 model

 

NIRSpec model

 

MIRI 1:3 scale model

• Near InfraRed Camera (NIRCam) is an infrared imager which will have a spectral coverage ranging from the edge of the visible (0.6 micrometers) through the near infrared (5 micrometers). NIRCam will also serve as the observatory's wavefront sensor, which is required for wavefront sensing and control activities. NIRCam was built by a team led by the University of Arizona, with Principal Investigator Marcia Rieke. The industrial partner is Lockheed-Martin's Advanced Technology Center located in Palo Alto, California.
• Near InfraRed Spectrograph (NIRSpec) will also perform spectroscopy over the same wavelength range. It was built by the European Space Agency at ESTEC in Noordwijk, Netherlands. The leading development team is composed of people from Airbus Defence and Space, Ottobrunn and Friedrichshafen, Germany, and the Goddard Space Flight Center; with Pierre Ferruit (École normale supérieure de Lyon) 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 multi-object mode relies on a complex micro-shutter mechanism to allow for simultaneous observations of hundreds of individual objects anywhere in NIRSpec's field of view. The mechanisms and their optical elements were designed, integrated and tested by Carl Zeiss Optronics GmbH of Oberkochen, Germany, under contract from Astrium.
• Mid-InfraRed Instrument (MIRI) will measure the mid-infrared wavelength range from 5 to 27 micrometers. It contains both a mid-infrared camera and an imaging spectrometer. MIRI was developed as a collaboration between NASA and a consortium of European countries, and is led by George Rieke (University of Arizona) and Gillian Wright (UK Astronomy Technology Centre, Edinburgh, part of the Science and Technology Facilities Council (STFC)). MIRI features similar wheel mechanisms as NIRSpec which are also developed and built by Carl Zeiss Optronics GmbH under contract from the Max Planck Institute for Astronomy, Heidelberg. The completed Optical Bench Assembly of MIRI was delivered to Goddard in mid-2012 for eventual integration into the ISIM. The temperature of the MIRI must not exceed 6 Kelvin (K): a helium gas mechanical cooler sited on the warm side of the environmental shield provides this cooling.
• Fine Guidance Sensor and Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS), led by the Canadian Space Agency under project scientist John Hutchings (Herzberg Institute of Astrophysics, National Research Council of Canada), 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 is also providing a Near Infrared Imager and Slitless Spectrograph (NIRISS) module for astronomical imaging and spectroscopy in the 0.8 to 5 micrometer wavelength range, led by principal investigator René Doyon at the University of Montreal. Because the NIRISS is physically mounted together with the FGS, they are often referred to as a single unit, but they serve entirely different purposes, with one being a scientific instrument and the other being a part of the observatory's support infrastructure.

NIRCam and MIRI feature starlight-blocking coronagraphs for observation of faint targets such as extrasolar planets and circumstellar disks very close to bright stars.

The infrared detectors for the NIRCam, NIRSpec, FGS, and NIRISS modules are being provided by Teledyne Imaging Sensors (formerly Rockwell Scientific Company). The James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM) and Command and Data Handling (ICDH) engineering team uses SpaceWire to send data between the science instruments and the data-handling equipment.

Spacecraft Bus

Diagram of the Spacecraft Bus. The solar panel is in green and the light purple flats are radiators shades

The Spacecraft Bus is the primary support component of the James Webb Space Telescope, that hosts a multitude of computing, communication, propulsion, and structural parts, bringing the different parts of the telescope together. Along with the Sunshield, it forms the Spacecraft Element of the space telescope. The other two major elements of the JWST are the Integrated Science Instrument Module (ISIM) and the Optical Telescope Element (OTE). Region 3 of ISIM is also inside the Spacecraft Bus; region 3 includes ISIM Command and Data Handling subsystem and the MIRI cryocooler.

The Spacecraft Bus is connected to Optical Telescope Element via the Deployable Tower Assembly, which also connects to the sunshield.

The structure of the Spacecraft Bus must support the 6.5-ton space telescope, while it itself weighs 350 kg (about 770 lb). It is made primarily of graphite composite material. It was assembled in California by 2015, and after that it had to be integrated with the rest of the space telescope leading up to its planned 2021 launch. The bus can provide pointing of one-arcsecond and isolates vibration down to two milliarcseconds.

The Spacecraft Bus is on the Sun-facing "warm" side and operates at a temperature of about 300 K. Everything on the Sun facing side must be able to handle the thermal conditions of JWST's halo orbit, which has one side in continuous sunlight and the other in the shade of the spacecraft sunshield.

Another important aspect of the Spacecraft Bus is the central computing, memory storage, and communications equipment. The processor and software direct data to and from the instruments, to the solid-state memory core, and to the radio system which can send data back to Earth and receive commands. The computer also controls the pointing and moment of the spacecraft, taking in sensor data from the gyroscopes and star tracker, and sending the necessary commands to the reaction wheels or thrusters depending.

Launch and mission length

Launch is planned March 30, 2021, on an Ariane 5 rocket. The observatory attaches to the Ariane 5 rocket via a launch vehicle adapter ring which could be used by a future spacecraft to grapple the observatory to attempt to fix gross deployment problems. However, the telescope itself is not serviceable, and astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope. Its nominal mission time is five years, with a goal of ten years. JWST needs to use propellant to maintain its halo orbit around L2, which provides an upper limit to its designed lifetime, and it is being designed to carry enough for ten years. The planned five year science mission begins after a 6-month commissioning phase. An L2 orbit is only meta-stable so it requires orbital station-keeping or an object will drift away from this orbital configuration.

Comparison with other telescopes

Comparison with Hubble primary mirror

 

Calisto architecture for SAFIR would be a successor to Spitzer, requiring even cooler passive cooling than JWST (5 Kelvin).

 

Atmospheric windows in the infrared: much of this type of light is blocked when viewed from the Earth's surface. It would be like looking at a rainbow but only seeing one shade of one color

The desire for a large infrared space telescope traces back decades; in the United States the Shuttle Infrared Telescope Facility was planned while the Space Shuttle was in development and the potential for infrared astronomy was acknowledged at that time. Compared to ground telescopes, space observatories were free from atmospheric absorption of infrared light; this would be a whole "new sky" for astronomers.

The tenuous atmosphere above the 400 km nominal flight altitude has no measurable absorption so that detectors operating at all wavelengths from 5 µm to 1000 µm can achieve high radiometric sensitivity.

— S. G. McCarthy & G. W. Autio, 1978

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. This has meant most infrared telescopes have a lifespan limited by their coolant, as short as a few months, maybe a few years at most. It has been 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 and NEOWISE. Another example is Hubble's NICMOS instrument, which started out using a block of nitrogen ice that depleted after a couple of years, but was then converted to a cryocooler that worked continuously. The James Webb Space Telescope is designed to cool itself without a dewar, using a combination of sunshield and radiators with the mid-infrared instrument using an additional cryocooler.

The telescope's delays and cost increases can be compared to the Hubble Space Telescope. When Hubble formally started in 1972, it had an estimated development cost of $300 million (or about $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 $9 billion by 2006.

In contrast to other proposed observatories, most of which have already been canceled or put on hold, including Terrestrial Planet Finder (2011), Space Interferometry Mission (2010), International X-ray Observatory (2011), MAXIM (Microarcsecond X-ray Imaging Mission), SAFIR (Single Aperture Far-Infrared Observatory), SUVO (Space Ultraviolet-Visible Observatory), and the SPECS (Submillimeter Probe of the Evolution of Cosmic Structure), the JWST is the last big NASA astrophysics mission of its generation to be built.

History

Development and construction

Early development work for a Hubble successor between 1989 and 1994 led to the Hi-Z telescope concept, a fully baffled 4-meter aperture infrared telescope that would recede to an orbit at 3 AU. This distant orbit would have benefited from reduced light noise from zodiacal dust. Other early plans called for a NEXUS precursor telescope mission.

In the "faster, better, cheaper" era in the mid-1990s, NASA leaders pushed for a low-cost space telescope. The result was the NGST concept, with an 8-meter aperture and located at L₂, roughly estimated to cost $500 million. In 1997, NASA worked with the Goddard Space Flight Center, Ball Aerospace, and TRW to conduct technical requirement and cost studies, and in 1999 selected Lockheed Martin and TRW for preliminary concept studies. Launch was at that time planned for 2007, but the launch date has subsequently been pushed back many times (see table further down).

A JWST mirror segment, 2010

In 2002, NASA awarded the $824.8 million prime contract for the NGST, now renamed the James Webb Space Telescope, to TRW. The design called for a descoped 6.1-meter (20 ft) primary mirror and a launch date of 2010. Later that year, TRW was acquired by Northrop Grumman in a hostile bid and became Northrop Grumman Space Technology.

NASA's Goddard Space Flight Center in Greenbelt, Maryland, is leading the management of the observatory project. The project scientist for the James Webb Space Telescope is John C. Mather. Northrop Grumman Aerospace Systems serves as the primary contractor for the development and integration of the observatory. They are responsible for developing and building the spacecraft element, which includes both the spacecraft bus and sunshield. Ball Aerospace has been subcontracted to develop and build the Optical Telescope Element (OTE). Northrop Grumman's Astro Aerospace business unit has been contracted to build the Deployable Tower Assembly (DTA) which connects the OTE to the spacecraft bus and the Mid Boom Assembly (MBA) which helps to deploy the large sunshields on orbit. Goddard Space Flight Center is also responsible for providing the Integrated Science Instrument Module (ISIM). A solar panel converts sunlight into electrical power that recharges batteries needed to operate the other subsystems, as well as the science instruments, but heat from these operations must be dissipated for optimal instrument performance at 50 K (−220 °C; −370 °F).

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 micrometers. Other major features of the observatory were unchanged. Following the re-planning, the project was independently reviewed in April 2006. The review concluded the project was technically sound, but that funding phasing at NASA needed to be changed. NASA re-phased its JWST budgets accordingly.

In the 2005 re-plan, the life-cycle cost of the project was estimated at about 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. ESA is contributing about €300 million, including the launch, and the Canadian Space Agency about $39M Canadian.

In January 2007, nine of the ten technology development items in the project successfully passed a non-advocate review. These technologies were deemed sufficiently mature to retire significant risks in the project. The remaining technology development item (the MIRI cryocooler) completed its technology maturation milestone in April 2007. This technology review represented the beginning step in the process that ultimately moved the project into its detailed design phase (Phase C). By May 2007, costs were still on target. In March 2008, the project successfully completed its Preliminary Design Review (PDR). In April 2008, the project passed the Non-Advocate Review. Other passed reviews include the Integrated Science Instrument Module review in March 2009, the Optical Telescope Element review completed in October 2009, and 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). As is typical for a complex design that cannot be changed once launched, there are detailed reviews of every portion of design, construction, and proposed operation. New technological frontiers have been pioneered by the project, and it has passed its design reviews. In the 1990s it was unknown if a telescope so large and low mass was possible.

Assembly of the hexagonal segments of the primary mirror, which was done via robotic arm, began in November 2015 and was completed in February 2016. Final construction of the Webb telescope was completed in November 2016, after which extensive testing procedures began. In March 2018, NASA delayed the JWST's launch an additional year 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 JWST's launch an additional 10 months to March 2021, based on the assessment of the independent review board convened after the failed March 2018 test deployment.

Cost and schedule issues

The JWST has a history of major cost overruns and delays which have resulted in part from outside factors such as delays in deciding on a launch vehicle and adding extra funding for contingencies. By 2006, $1 billion had been spent on developing JWST, with the budget at about $4.5 billion at that time. A 2006 article in the journal Nature noted a study in 1984 by the Space Science Board, which estimated that a next generation infrared observatory would cost $4 billion (about $7 billion in 2006 dollars). Because the runaway budget diverted funding from other research, the science journal Nature described the James Webb as "the telescope that ate astronomy" in 2010. In June 2011, it was reported that the Webb telescope would cost at least four times more than originally proposed, and launch at least seven years late. Initial budget estimates were that the observatory would cost $1.6 billion and launch in 2011.

The telescope was originally estimated to cost $1.6bn but the cost estimate grew throughout the early development and had reached about $5bn by the time the mission was formally confirmed for construction start in 2008. In summer 2010, the mission passed its Critical Design Review with excellent grades on all technical matters, but schedule and cost slips at that time prompted Maryland US Senator Barbara Mikulski to call for an independent review of the project. The Independent Comprehensive Review Panel (ICRP) chaired by J. Casani (JPL) found that the earliest possible launch date was in late 2015 at an extra cost of $1.5bn (for a total of $6.5bn). They also pointed out that this would have required extra funding in FY2011 and FY2012 and that any later launch date would lead to a higher total cost.

On 6 July 2011, the United States House of Representatives' appropriations committee on Commerce, Justice, and Science moved to cancel the James Webb project by proposing an FY2012 budget that removed $1.9bn from NASA's overall budget, of which roughly one quarter was for JWST. $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". However, in November 2011, Congress reversed plans to cancel the JWST and instead capped additional funding to complete the project at $8 billion. Termination of the JWST project as proposed by the House appropriation committee also would have imperiled funding to other missions, such as the Wide-Field Infrared Survey Telescope.

The American Astronomical Society issued a statement in support of JWST in 2011, as did Maryland US Senator Barbara Mikulski. A number of editorials supporting JWST appeared in the international press during 2011 as well.

Some scientists have expressed concerns about growing costs and schedule delays for the Webb telescope, which competes for scant astronomy budgets and thus threatens funding for other space science programs. A review of NASA budget records and status reports noted that the JWST is plagued by many of the same problems that have affected other major NASA projects. Repairs and additional testing included underestimates of the telescope's cost that failed to budget for expected technical glitches, missed budget projections, and evaluation of components to estimate extreme launch conditions, thus extending the schedule and increasing costs further.

One reason for the early cost growth is that it is difficult to forecast the cost of development, and in general budget predictability improved when initial development milestones were achieved. By the mid-2010s, the U.S. contribution was still expected to cost $8.8 billion. In 2007, the expected ESA contribution was about €350 million. With the U.S. and international funding combined, the overall cost not including extended operations is projected to be over $10 billion when completed. On 27 March 2018, NASA officials announced that JWST's launch would be pushed back to May 2020 or later, and admitted that the project's costs might exceed the $8.8 billion price tag. In the March 27 press release announcing the latest delay, NASA said that it will release a revised cost estimate after a new launch window is determined in cooperation with the ESA. If this cost estimate exceeds the $8 billion cap Congress put in place in 2011, as is considered unavoidable, NASA will have to have the mission re-authorized by the legislature.

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 will provide the Fine Guidance Sensor and the Near-Infrared Imager Slitless Spectrograph plus manpower to support operations.

Participating countries

•  Austria
•  Belgium
•  Canada
•  Czech Republic
•  Denmark
•  Finland
•  France
•  Germany
•  Greece
•  Ireland
•  Italy
•  Luxembourg
•  Netherlands
•  Norway
•  Portugal
•  Spain
•  Sweden
•   Switzerland
•  United Kingdom
•  United States

Public displays and outreach

Early full-scale model on display at NASA Goddard (2005)

A large telescope model has been on display at various places since 2005: in the United States at Seattle, Washington; Colorado Springs, Colorado; Greenbelt, Maryland; Rochester, New York; Manhattan, New York; and Orlando, Florida; and elsewhere at Paris, France; Dublin, Ireland; Montreal, Quebec, Canada; Hatfield, United Kingdom; and Munich, Germany. The model was built by the main contractor, Northrop Grumman Aerospace Systems.

In May 2007, a full-scale model of the telescope was assembled for display at the Smithsonian Institution's National Air and Space Museum on the National Mall, Washington D.C. The model was intended to give the viewing public a better understanding of the size, scale and complexity of the satellite, as well as pique the interest of viewers in science and astronomy in general. The model is significantly different from the telescope, as the model must withstand gravity and weather, so is constructed mainly of aluminum and steel measuring approximately 24×12×12 m (79×39×39 ft) and weighs 5.5 tonnes (12,000 lb).

The model was on display in New York City's Battery Park during the 2010 World Science Festival, where it served as the backdrop for a panel discussion featuring Nobel Prize laureate John C. Mather, astronaut John M. Grunsfeld and astronomer Heidi Hammel. In March 2013, the model was on display in Austin, Texas for SXSW 2013.

Mission

The JWST's primary scientific mission has four key goals: to search for light from the first stars and galaxies that formed in the Universe after the Big Bang, to study the formation and evolution of galaxies, to understand the formation of stars and planetary systems and to study planetary systems and the origins of life. 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 the 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. The JWST will be sensitive to a range of wavelengths from 0.6 (orange light) to 28 micrometers (deep infrared radiation at about 100 K (−170 °C; −280 °F)).

JWST may be used to gather information on the dimming light of star KIC 8462852, which was discovered in 2015, and has some abnormal light-curve properties.

Orbit

JWST will not be exactly at the L2 point, but circle around it in a halo orbit.

 

Two alternate Hubble Space Telescope views of the Carina Nebula, comparing ultraviolet and visible (top) and infrared (bottom) astronomy. Far more stars are visible in the latter.

 

The JWST will be located near the second Lagrange point (L₂) of the Earth-Sun system, which is 1,500,000 kilometers (930,000 mi) from Earth, directly opposite to the Sun. Normally an object circling the Sun farther out than Earth would take longer than one year to complete its orbit, but near the L₂ point the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time it takes the Earth. The telescope will circle about the L₂ point in a halo orbit, which will be inclined with respect to the ecliptic, have a radius of approximately 800,000 kilometers (500,000 mi), and take about half a year to complete. Since L₂ 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 L₂ point. This requires some station-keeping: around 2–4 m/s per year from the total budget of 150 m/s. Two sets of thrusters constitute the observatory's propulsion system.

Infrared astronomy

Infrared observations can see objects hidden in visible light, such as HUDF-JD2 shown.

JWST is the formal successor to the Hubble Space Telescope (HST), and since its primary emphasis is on infrared observation, 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. Observing in the infrared is a key technique for achieving this because of cosmological redshift 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, 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 these objects 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 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, such as the molecular clouds where stars are born, the circumstellar disks that give rise to planets, and the cores of active galaxies.

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 dwarfs, planets both in our own and other solar systems, comets and Kuiper belt objects that will be observed with the Mid-Infrared Instrument (MIRI) requiring an additional cryocooler.

Some of the missions in infrared astronomy that impacted JWST development were Spitzer and also the WMAP probe. Spitzer showed the importance of mid-infrared, such as in its 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 launched in the early 2000s, in time to influence JWST development.

Ground support and operations

The Space Telescope Science Institute (STScI), located in Baltimore, Maryland on the Homewood campus of Johns Hopkins University, was selected as the Science and Operations Center (S&OC) for JWST with an initial budget of $162.2 million intended to support operations through the first year after launch.^[127] In this capacity, STScI will be responsible for the scientific operation of the telescope and delivery of data products to the astronomical community. Data will be transmitted from JWST to the ground via NASA's Deep Space Network, 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 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.

Most of the data processing on the telescope is done by conventional single-board computers. The conversion of the analog science data to digital form is performed by the custom-built SIDECAR ASIC (System for Image Digitization, Enhancement, Control And Retrieval Application Specific Integrated Circuit). NASA stated that the SIDECAR ASIC will include all the functions of a 9 kg (20 lb) instrument box in a 3 cm package and consume only 11 milliwatts of power. Since this conversion must be done close to the detectors, on the cool side of the telescope, the low power use of this IC will be crucial for maintaining the low temperature required for optimal operation of the JWST.

After-launch deployment

Nearly a month after launch, a trajectory correction will be initiated to place the JWST into a halo orbit at the L₂ lagrangian point.

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  JWST after-launch deployment planned timeline
  

Observations and science programs

JWST observing time will be allocated through a Director's Discretionary Early Release Science (DD-ERS) Program, a Guaranteed Time Observations (GTO) Program, and a General Observers (GO) 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. GO programs will be selected through peer review by a Time Allocation Committee (TAC), similar to the proposal review process used for the Hubble Space Telescope. JWST observing time is expected to be highly oversubscribed.

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 will 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, exoplanets, stars and star formation, nearby and distant galaxies, gravitational lenses, and quasars.

From dust to pebbles to planets – insight into the birth of a solar system

05 September 2018 by Ethan Bilby

Original link:  https://horizon-magazine.eu/article/dust-pebbles-planets-insight-birth-solar-system_en.html?utm_source=fb&utm_medium=share#

Scientists are working out how cosmic dust turns

into hard, spherical pebbles which can then

develop into planets.

Image credit - NASA/JPL-Caltech

Detailed simulations of planetary formation are revealing how tiny grains of dust turn into giant planets and could shed light on where to find new Earth-like worlds.

Scientists theorise that planets form from rotating discs of gas that surround newly formed stars, known as proto-planetary discs. Pebble-sized objects in these discs then clump together to form cores of would-be planets.

Professor Anders Johansen from Lund University in Sweden, has gone right down to the level of atomic nuclei and molecules to try and work out how cosmic dust particles stick together in pebbles and then turn into baby planets, known as planetesimals.

‘Planet formation takes place when these dust particles collide, and they grow to larger and larger sizes,’ he said. ‘This growth takes us then from micrometres, all the way up to 10,000 kilometres or so.’

One clue to how this dust forms into pebbles can be found on Earth in meteorites – pieces of asteroids that are leftovers from the formation of the solar system.

‘There’s a mystery in there,’ Prof. Johansen said. ‘If you look inside an asteroid, you do find millimetre-sized pebbles, which is fine. But the problem with those pebbles is they are not what we expect them to be. We would expect them to be fluffy dust aggregates, a bit like if you have a sandbox after it rains, and you can pick up a piece of dried out sand that is very fragile,’ he said.

Instead, the pebbles are spherical and hard, like they have been heated and cooled – similar to objects that have been struck by lightning.

‘Lightning takes place as thunderclouds discharge their electric charge to the ground,’ said Prof. Johansen. ‘This discharge is very similar to the shock you experience from the static electricity when you put on a jumper.’

‘If we see a certain composition of the system … that might allow us to see that there might be habitable planets in those systems.’

Dr Bertram Bitsch, Max Planck Institute for Astronomy, Heidelberg, Germany

Prof. Johansen theorised that there must be a mechanism during planet formation that creates positively and negatively charged particles, and he and his team investigated what that was.

‘While a thundercloud obtains a charge difference between its top and bottom by falling hail particles, we found that in the protoplanetary disc the decay of a radioactive element called Aluminium-26 is very efficient at charging dust clouds,’ he said.

Chemical composition

The finding was part of a project called PLANETESYS, which is using computer simulations to replicate the physical processes taking place when planets form – all the way from dust to a planetary system. It includes details about the chemical composition of each pebble.

One thing Prof. Johansen can examine from looking at this chemical composition is how planets accrete water – a vital ingredient for life.

‘An obvious question is, “How much water does a planet get?” We can begin to speculate about if it’s normal to get the Earth’s amount of water, if it’s a lot of water or a little bit. But maybe you can also get too much water, which may be good for life but not good for civilisations,’ he said.

Dr Bertram Bitsch from the Max Planck Institute for Astronomy in Heidelberg, Germany, says that understanding more about how planets arise would help identify potentially habitable planets elsewhere in the universe.

‘If you understand more (about) the formation process of how we can make a system like the solar system, then we can maybe make predictions (about) how often these systems would exist and how common it would be to find Earth-like planets (orbiting) other stars.’  

‘Then, if we see a certain composition of the system … that might allow us to see that there might be habitable planets in those systems.’

Recipe

Dr Bitsch thinks he might know the recipe for how solar systems end up with Earth-like planets. With a careful blending of conditions, from where baby planets form, to their chemical composition and gravitational interactions, he can try to model the conditions to generate solar systems with habitable planets.

But figuring out the right recipe requires working backwards after running many simulations with complex supercomputing power, which he’s doing in a project called PAMDORA which runs until 2022.

‘I want to use computer simulations … where we look at the gravitational interactions between multiple bodies to model the stages from planetesimals all the way to fully formed planetary systems with terrestrial planets, super Earths, and gas giants,’ he said.

In his simulations, Dr Bitsch looks at the how pebbles in the swirling discs form into moon-size planetary embryos, which then develop into fully formed planets.

Altering the different mechanisms at work can influence what types of planets a solar system may end up with.

‘There are many different pathways that can happen, and many different parameters that can influence the outcome of the simulations,’ he said. ‘For example, how big are the pebbles, how many would there be, and where would your initial planetesimals form that would then start to form proto-planets?’

To see which variables matter most, he runs hundreds of computer simulations that last weeks at a time and can simulate tens of millions of years to model the highly chaotic meetings of multiple objects.

For Earth-like planets, one key factor is how close baby planets form to their home star, since the difference in temperature can determine if planets accrete water directly during the gas-disc stage or from a late water delivery from asteroids or comets, like for our own Earth.

‘One thing that is already in the code is looking at the composition of super-Earths. For example, are they rocky or dominated by water-ice?’ Dr Bitsch said.

Super-Earths, which are planets like the Earth, but maybe two to ten times more massive, don’t exist in our solar system, but are relatively common among other stars.

‘Lots of super-Earths have been found and detected, and the question is what are they made of? This can give us the answer to where they have been formed.’

 The research in this article was funded by the European Research Council. If you liked this article, please consider sharing it on social media.

Spitzer Space Telescope

From Wikipedia, the free encyclopedia

Spitzer Space Telescope

Artist rendering of the Spitzer Space Telescope
Names	Space Infrared Telescope Facility
Mission type	Infrared space telescope
Operator	NASA / JPL / Caltech
COSPAR ID	2003-038A
SATCAT no.	27871
Website	http://www.spitzer.caltech.edu/
Mission duration	Planned: 2.5 to 5+ years Primary mission: 5 years, 8 months, 19 days Elapsed: 15 years, 7 days
Spacecraft properties
Manufacturer	Lockheed Ball Aerospace
Launch mass	950 kg (2,094 lb)
Dry mass	884 kg (1,949 lb)
Payload mass	851.5 kg (1,877 lb)
Start of mission
Launch date	25 August 2003, 05:35:39 UTC
Rocket	Delta II 7920H
Launch site	Cape Canaveral SLC-17B
Entered service	18 December 2003
Orbital parameters
Reference system	Heliocentric
Regime	Earth-trailing
Eccentricity	0.011
Perihelion	1.003 AU
Aphelion	1.026 AU
Inclination	1.13°
Period	373.2 days
Epoch	16 March 2017 00:00:00
Main telescope
Type	Ritchey–Chrétien
Diameter	0.85 m (2.8 ft)
Focal length	10.2 m (33 ft)
Wavelengths	infrared, 3.6–160 µm

The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF), is an infrared space telescope launched in 2003 and still operating as of 2018. It is the fourth and final of the NASA Great Observatories program.

The planned mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009. Without liquid helium to cool the telescope to the very low temperatures needed to operate, most of the instruments are no longer usable. However, the two shortest-wavelength modules of the IRAC camera are still operable with the same sensitivity as before the cryogen was exhausted, and have continued to be used to the present in the Spitzer Warm Mission. All Spitzer data, from both the primary and warm phases, are archived at the Infrared Science Archive (IRSA).

In keeping with NASA tradition, the telescope was renamed after its successful demonstration of operation, on 18 December 2003. Unlike most telescopes that are named after famous deceased astronomers by a board of scientists, the new name for SIRTF was obtained from a contest open to the general public.

The contest led to the telescope being named in honor of astronomer Lyman Spitzer, who had promoted the concept of space telescopes in the 1940s. Spitzer wrote a 1946 report for RAND Corporation describing the advantages of an extraterrestrial observatory and how it could be realized with available or upcoming technology. He has been cited for his pioneering contributions to rocketry and astronomy, as well as "his vision and leadership in articulating the advantages and benefits to be realized from the Space Telescope Program."

The US$720 million Spitzer was launched on 25 August 2003 at 05:35:39 UTC from Cape Canaveral SLC-17B aboard a Delta II 7920H rocket.

It follows a heliocentric instead of geocentric orbit, trailing and drifting away from Earth's orbit at approximately 0.1 astronomical units per year (a so-called "earth-trailing" orbit). The primary mirror is 85 centimeters (33 in) in diameter, f/12, made of beryllium and was cooled to 5.5 K (−268 °C; −450 °F). The satellite contains three instruments that allow it to perform astronomical imaging and photometry from 3.6 to 160 micrometers, spectroscopy from 5.2 to 38 micrometers, and spectrophotometry from 5 to 100 micrometers.

History

By the early 1970s, astronomers began to consider the possibility of placing an infrared telescope above the obscuring effects of Earth's atmosphere. In 1979, a report from the National Research Council of the National Academy of Sciences, A Strategy for Space Astronomy and Astrophysics for the 1980s, identified a Space Infrared Telescope Facility (SIRTF) as "one of two major astrophysics facilities [to be developed] for Spacelab", a Shuttle-borne platform. Anticipating the major results from an upcoming Explorer satellite and from the Shuttle mission, the report also favored the "study and development of ... long-duration spaceflights of infrared telescopes cooled to cryogenic temperatures."

The launch in January 1983 of the Infrared Astronomical Satellite, jointly developed by the United States, the Netherlands, and the United Kingdom, to conduct the first infrared survey of the sky, whetted the appetites of scientists worldwide for follow-up space missions capitalizing on the rapid improvements in infrared detector technology.

Earlier infrared observations had been made by both space-based and ground-based observatories. Ground-based observatories have the drawback that at infrared wavelengths or frequencies, both the Earth's atmosphere and the telescope itself will radiate (glow) strongly. Additionally, the atmosphere is opaque at most infrared wavelengths. This necessitates lengthy exposure times and greatly decreases the ability to detect faint objects. It could be compared to trying to observe the stars at noon. Previous space observatories (such as IRAS, the Infrared Astronomical Satellite, and ISO, the Infrared Space Observatory) were launched during the 1980s and 1990s and great advances in astronomical technology have been made since then.

SIRTF in a Kennedy Space Center clean room

Launch of SIRTF in 2003 aboard the 300th Delta rocket

Most of the early concepts envisioned repeated flights aboard the NASA Space Shuttle. This approach was developed in an era when the Shuttle program was expected to support weekly flights of up to 30 days duration. A May 1983 NASA proposal described SIRTF as a Shuttle-attached mission, with an evolving scientific instrument payload. Several flights were anticipated with a probable transition into a more extended mode of operation, possibly in association with a future space platform or space station. SIRTF would be a 1-meter class, cryogenically cooled, multi-user facility consisting of a telescope and associated focal plane instruments. It would be launched on the Space Shuttle and remain attached to the Shuttle as a Spacelab payload during astronomical observations, after which it would be returned to Earth for refurbishment prior to re-flight. The first flight was expected to occur about 1990, with the succeeding flights anticipated beginning approximately one year later. However, the Spacelab-2 flight aboard STS-51-F showed that the Shuttle environment was poorly suited to an onboard infrared telescope due to contamination from the relatively "dirty" vacuum associated with the orbiters. By September 1983 NASA was considering the "possibility of a long duration [free-flyer] SIRTF mission".

Spitzer is the only one of the Great Observatories not launched by the Space Shuttle, as was originally intended. However, after the 1986 Challenger disaster, the Centaur LH2–LOX upper stage, which would have been required to place it in its final orbit, was banned from Shuttle use. The mission underwent a series of redesigns during the 1990s, primarily due to budget considerations. This resulted in a much smaller but still fully capable mission that could use the smaller Delta II expendable launch vehicle.

One of the most important advances of this redesign was an Earth-trailing orbit. Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from the Earth, and consequently require large amounts of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling such as the sun shield, against the single remaining major heat source to drastically reduce the total mass of helium needed, resulting in an overall smaller lighter payload, with major cost savings. This orbit also simplifies telescope pointing, but does require the NASA Deep Space Network for communications.

The primary instrument package (telescope and cryogenic chamber) was developed by Ball Aerospace & Technologies, in Boulder, Colorado. The individual instruments were developed jointly by industrial, academic, and government institutions, the principals being Cornell, the University of Arizona, the Smithsonian Astrophysical Observatory, Ball Aerospace, and Goddard Spaceflight Center. The shorter-wavelength infrared detectors were developed by Raytheon in Goleta, California. Raytheon used indium antimonide and a doped silicon detector in the creation of the infrared detectors. It is stated that these detectors are 100 times more sensitive than what was once available in the beginning of the project during the 1980s. The far-IR detectors (70 - 160 micrometers) were developed jointly by the University of Arizona and Lawrence Berkeley National Laboratory using Gallium-doped Germanium. The spacecraft was built by Lockheed Martin. The mission is operated and managed by the Jet Propulsion Laboratory and the Spitzer Science Center, located on the Caltech campus in Pasadena, California.

Spitzer ran out of liquid helium coolant on 15 May 2009, which stopped far-IR observations. Only the IRAC instrument remains in use, and only at the two shorter wavelength bands (3.6 µm and 4.5 µm). The telescope equilibrium temperature is now around 30 K (−243 °C; −406 °F), and IRAC continues to produce valuable images at those wavelengths as the "Spitzer Warm Mission".

Instruments

Henize 206 viewed by different instruments in March 2004. The separate IRAC and MPIS images are at right.

Spitzer carries three instruments on-board:

Infrared Array Camera (IRAC)

An infrared camera which operates simultaneously on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm). Each module uses a 256×256-pixel detector—the short wavelength pair use indium antimonide technology, the long wavelength pair use arsenic-doped silicon impurity band conduction technology. The principal investigator is Giovanni Fazio of Harvard–Smithsonian Center for Astrophysics; the flight hardware was built by NASA Goddard Space Flight Center.

Infrared Spectrograph (IRS)

An infrared spectrometer with four sub-modules which operate at the wavelengths 5.3–14 µm (low resolution), 10–19.5 µm (high resolution), 14–40 µm (low resolution), and 19–37 µm (high resolution). Each module uses a 128×128-pixel detector—the short wavelength pair use arsenic-doped silicon blocked impurity band technology, the long wavelength pair use antimony-doped silicon blocked impurity band technology. The principal investigator is James R. Houck of Cornell University; the flight hardware was built by Ball Aerospace.

Multiband Imaging Photometer for Spitzer (MIPS)

Three detector arrays in the far infrared (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm). The 24 µm detector is identical to one of the IRS short wavelength modules. The 70 µm detector uses gallium-doped germanium technology, and the 160 µm detector also uses gallium-doped germanium, but with mechanical stress added to each pixel to lower the bandgap and extend sensitivity to this long wavelength. The principal investigator is George H. Rieke of the University of Arizona; the flight hardware was built by Ball Aerospace.

Results

Spitzer's first light image of IC 1396.

The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a big swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe. Since then, many monthly press releases have highlighted Spitzer's capabilities, as the NASA and ESA images do for the Hubble Space Telescope.

As one of its most noteworthy observations, in 2005, SST became the first telescope to directly capture light from exoplanets, namely the "hot Jupiters" HD 209458 b and TrES-1b, although it did not resolve that light into actual images. This was the first time extrasolar planets had actually been visually seen; earlier observations had been indirectly made by drawing conclusions from behaviors of the stars the planets were orbiting. The telescope also discovered in April 2005 that Cohen-kuhi Tau/4 had a planetary disk that was vastly younger and contained less mass than previously theorized, leading to new understandings of how planets are formed.

The Helix Nebula. Blue shows infrared light of 3.6 to 4.5 micrometers; green shows infrared light of 5.8 to 8 micrometers; and red shows infrared light of 24 micrometers.

While some time on the telescope is reserved for participating institutions and crucial projects, astronomers around the world also have the opportunity to submit proposals for observing time. Important targets include forming stars (young stellar objects, or YSOs), planets, and other galaxies. Images are freely available for educational and journalistic purposes.

In 2004, it was reported that Spitzer had spotted a faintly glowing body that may be the youngest star ever seen. The telescope was trained on a core of gas and dust known as L1014 which had previously appeared completely dark to ground-based observatories and to ISO (Infrared Space Observatory), a predecessor to Spitzer. The advanced technology of Spitzer revealed a bright red hot spot in the middle of L1014.

Scientists from the University of Texas at Austin, who discovered the object, believe the hot spot to be an example of early star development, with the young star collecting gas and dust from the cloud around it. Early speculation about the hot spot was that it might have been the faint light of another core that lies 10 times further from Earth but along the same line of sight as L1014. Follow-up observation from ground-based near-infrared observatories detected a faint fan-shaped glow in the same location as the object found by Spitzer. That glow is too feeble to have come from the more distant core, leading to the conclusion that the object is located within L1014. (Young et al., 2004)
In 2005, astronomers from the University of Wisconsin at Madison and Whitewater determined, on the basis of 400 hours of observation on the Spitzer Space Telescope, that the Milky Way galaxy has a more substantial bar structure across its core than previously recognized.

Artificial color image of the Double Helix Nebula, thought to be generated at the galactic center by magnetic torsion 1000 times greater than the Sun's.

Also in 2005, astronomers Alexander Kashlinsky and John Mather of NASA's Goddard Space Flight Center reported that one of Spitzer's earliest images may have captured the light of the first stars in the universe. An image of a quasar in the Draco constellation, intended only to help calibrate the telescope, was found to contain an infrared glow after the light of known objects was removed. Kashlinsky and Mather are convinced that the numerous blobs in this glow are the light of stars that formed as early as 100 million years after the Big Bang, redshifted by cosmic expansion.

In March 2006, astronomers reported an 80-light-year long (25 pc) nebula near the center of the Milky Way Galaxy, the Double Helix Nebula, which is, as the name implies, twisted into a double spiral shape. This is thought to be evidence of massive magnetic fields generated by the gas disc orbiting the supermassive black hole at the galaxy's center, 300 light-years (92 pc) from the nebula and 25,000 light-years (7,700 pc) from Earth. This nebula was discovered by Spitzer and published in the magazine Nature on 16 March 2006.

In May 2007, astronomers successfully mapped the atmospheric temperature of HD 189733 b, thus obtaining the first map of some kind of an extrasolar planet.

Since September 2006 the telescope participates in a series of surveys called the Gould Belt Survey, observing the Gould's Belt region in multiple wavelengths. The first set of observations by the Spitzer Space Telescope were completed from 21 September 2006 through 27 September. Resulting from these observations, the team of astronomers led by Dr. Robert Gutermuth, of the Harvard–Smithsonian Center for Astrophysics reported the discovery of Serpens South, a cluster of 50 young stars in the Serpens constellation.

The Andromeda Galaxy taken by IPS at 24 micrometers

Scientists have long wondered how tiny silicate crystals, which need high temperatures to form, have found their way into frozen comets, born in the very cold environment of the Solar System's outer edges. The crystals would have begun as non-crystallized, amorphous silicate particles, part of the mix of gas and dust from which the Solar System developed. This mystery has deepened with the results of the Stardust sample return mission, which captured particles from Comet Wild 2. Many of the Stardust particles were found to have formed at temperatures in excess of 1000 K.

In May 2009, Spitzer researchers from Germany, Hungary and the Netherlands found that amorphous silicate appears to have been transformed into crystalline form by an outburst from a star. They detected the infrared signature of forsterite silicate crystals on the disk of dust and gas surrounding the star EX Lupi during one of its frequent flare-ups, or outbursts, seen by Spitzer in April 2008. These crystals were not present in Spitzer's previous observations of the star's disk during one of its quiet periods. These crystals appear to have formed by radiative heating of the dust within 0.5 AU of EX Lupi.

In August 2009, the telescope found evidence of a high-speed collision between two burgeoning planets orbiting a young star.

In October 2009, astronomers Anne J. Verbiscer, Michael F. Skrutskie, and Douglas P. Hamilton published findings of the "Phoebe ring" of Saturn, which was found with the telescope; the ring is a huge, tenuous disc of material extending from 128 to 207 times the radius of Saturn.

GLIMPSE and MIPSGAL surveys

GLIMPSE, the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, is a survey spanning 300° of the inner Milky Way galaxy. It consists of approximately 444,000 images taken at four separate wavelengths using the Infrared Array Camera.

MIPSGAL is a similar survey covering 278° of the galactic disk at longer wavelengths.
On 3 June 2008, scientists unveiled the largest, most detailed infra-red portrait of the Milky Way, created by stitching together more than 800,000 snapshots, at the 212th meeting of the American Astronomical Society in St. Louis, Missouri. This composite survey is now viewable with the GLIMPSE/MIPSGAL Viewer.

2010s

An arrow points to the embryonic star HOPS-68, where scientists believe forsterite crystals are raining down onto the central dust disk.

Spitzer observations, announced in May 2011, indicate that tiny forsterite crystals might be falling down like rain on to the protostar HOPS-68. The discovery of the forsterite crystals in the outer collapsing cloud of the protostar is surprising, because the crystals form at lava-like high temperatures, yet they are found in the molecular cloud where the temperatures are about −170 °C (103 K; −274 °F). This led the team of astronomers to speculate that the bipolar outflow from the young star may be transporting the forsterite crystals from near the star's surface to the chilly outer cloud.

In January 2012, it was reported that further analysis of the Spitzer observations of EX Lupi can be understood if the forsterite crystalline dust was moving away from the protostar at a remarkable average speed of 38 kilometres per second (24 mi/s). It would appear that such high speeds can arise only if the dust grains had been ejected by a bipolar outflow close to the star. Such observations are consistent with an astrophysical theory, developed in the early 1990s, where it was suggested that bipolar outflows garden or transform the disks of gas and dust that surround protostars by continually ejecting reprocessed, highly heated material from the inner disk, adjacent to the protostar, to regions of the accretion disk further away from the protostar.

In April 2015, Spitzer and the Optical Gravitational Lensing Experiment were reported as co-discovering one of the most distant planets ever identified: a gas giant about 13,000 light-years (4,000 pc) away from Earth.

Illustration of a brown dwarf combined with a graph of light curves from OGLE-2015-BLG-1319: Ground-based data (grey), Swift (blue), and Spitzer (red)

In June and July 2015, the brown dwarf OGLE-2015-BLG-1319 was discovered using the gravitational microlensing detection method in a joint effort between Swift, Spitzer, and the ground-based Optical Gravitational Lensing Experiment, the first time two space telescopes have observed the same microlensing event. This method was possible because of the large separation between the two spacecraft: Swift is in low-Earth orbit while Spitzer is more than one AU distant in an Earth-trailing heliocentric orbit. This separation provided significantly different perspectives of the brown dwarf, allowing for constraints to be placed on some of the object's physical characteristics.

Reported in March 2016, Spitzer and Hubble were used to discover the most distant-known galaxy, GN-z11. This object was seen as it appeared 13.4 billion years ago.

Spitzer Beyond

On 1 October 2016, Spitzer began its Observation Cycle 13, a ​2 ¹⁄₂ year extended mission nicknamed Beyond. One of the goals of this extended mission is to help prepare for the James Webb Space Telescope, also an infrared telescope, by identifying candidates for more detailed observations.

Another aspect of the Beyond mission are the engineering challenges of operating Spitzer in its progressing orbital phase. As the spacecraft moves farther from Earth on the same orbital path from the Sun, its antenna must point at increasingly higher angles to communicate with ground stations; this change in angle imparts more and more solar heating on the vehicle while its solar panels receive less sunlight.

Planet hunter

Artist's impression of the TRAPPIST-1 system

Spitzer has been put to work studying exoplanets thanks to creatively tweaking its hardware. This included doubling its stability by modifying its heating cycle, finding a new use for the "peak-up" camera, and analyzing the sensor at a sub-pixel level. Although in its "warm" mission, the spacecraft's passive cooling system keeps the sensors at 29 K (−244 °C; −407 °F). Spitzer can use the transit photometry and gravitational microlensing techniques to perform these observations. According to NASA's Sean Carey, "We never even considered using Spitzer for studying exoplanets when it launched. ... It would have seemed ludicrous back then, but now it's an important part of what Spitzer does."

Examples of exoplanets discovered using Spitzer include HD 219134 b in 2015, which was shown to be a rocky planet about 1.5 times as large as Earth in a three-day orbit around its star; and an unnamed planet found using microlensing located about 13,000 light-years (4,000 pc) from Earth.

In September–October 2016, Spitzer was used to discover five of a total of seven known planets around the star TRAPPIST-1, all of which are approximately Earth sized and likely rocky. Three of the discovered planets are located in the habitable zone, which means they are capable of supporting liquid water given sufficient parameters. Using the transit method, Spitzer helped measure the sizes of the seven planets and estimate the mass and density of the inner six. Further observations will help determine if there is liquid water on any of the planets.