Next Generation Space Telescope
Webpages concerning "Next Generation Space Telescope"
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Wikipedia-Article "Next Generation Space Telescope"
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| Organization | NASA, ESA, CSA |
|---|---|
| Wavelength regime | infrared |
| Orbit height | 1.5×106 km from Earth (L2 Lagrangian point) |
| Orbit period | 1 year |
| Launch date | (June 2013) |
| Deorbit date | (2018 - 2023) |
| Mass | 6,200 kg |
| Other names | Next Generation Space Telescope |
| Webpage | http://www.jwst.nasa.gov |
| Physical characteristics | |
| Telescope style | (refractor, Newtonian reflector, etc.) |
| Diameter | ~6.5m |
| Collecting area | 25m2 |
| Focal length | (m, ft) |
| Instruments | |
| NIRCam | Near IR Camera |
| NIRSpec | Near IR Spectrograph |
| MIRI | Mid IR Instrument |
| FGS | Fine Guidance Sensors |
The James Webb Space Telescope (JWST) is a planned orbital infrared observatory, intended (in part) to replace the aging Hubble Space Telescope. It will be jointly constructed and operated by CSA, ESA and NASA. Formerly called the Next Generation Space Telescope (or NGST), it was renamed after NASA's second administrator, James E. Webb, in 2002. The telescope's launch is planned for no earlier than June 2013.
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Mission
The JWST's primary mission is to examine the infrared remnants of the big bang, and thus to make observations of an earlier state of the universe than is possible today. To achieve this, sensors of unparalleled sensitivity will be used, which in turn requires that the entire Observatory be particularly cold, and that major sources of IR interference (notably the Sun, the Earth, and the Moon) be blocked. To this end, JWST will be accompanied by a large metalized fanfold sunshield, which will unravel to block infrared radiation from these sources. The telescope's lagrangian orbit (see below) ensures that the Earth and Sun occupy the same relative position in the telescope's view, and thus make the operation of this shield possible. It is due no earlier than June 2013. After a commissioning period of approximately 6 months, the Observatory will begin the science mission, which required to last a minimum of 5 years. The potential for extension of the science mission beyond this period exists, and the Observatory is being designed accordingly.
Optics
Although JWST has a planned mass half that of the Hubble, its primary mirror (a 6.5 meter beryllium reflector) is more than 5 times larger. As this diameter is much larger than any current launch vehicle, the mirror is composed of 18 segments, which will unfold after the telescope is launched. Sensitive micromotors and wavefront sensor will position the mirror segments in the correct location, but subsequent to this initial configuration they will only rarely be moved; unlike terrestrial telescopes like the Keck which continually adjust their mirror segments using active optics to overcome the effects of gravitational loading and wind loading.
Current Status
The JWST program is in its detailed design phase. In January 2007 the program is scheduled to undergo a non-advocate review in order to determine if the proposed designs and technologies are sufficiently mature to begin the major construction phase. Prior to that major milestone in April 2006 the program will be reviewed following a replanning phase begun in August 2005. That replanning was necessitated by the cost growth revealed in Spring 2005. The primary outcomes of the replanning are significant changes in the integration and test plans, a 22-month launch delay (from 2011 to 2013), and elimination of system level testing for observatory modes at wavelength shorter than 1.7 micrometres. Other major features of the observatory are unchanged following the replanning efforts.
Construction & Engineering
Northrop Grumman Space Technology serves as the primary contractor for the development and integration of the Observatory. They are responsible for developing and building the Spacecraft, which includes both the spacecraft bus and sunshield. Ball Aerospace has been subcontracted to develop and build the Optical Telescope Element (OTE). Goddard Space Flight Center is responsible for providing the Integrated Science Instrument Module (ISIM).
For the present architecture, the ISIM contains four science instruments and a fine guidance sensor. The primary science instrument of the Observatory is the NIRCam (Near InfraRed Camera), which will have a spectral coverage ranging from the edge of the visible (0.6 micrometres) through the near IR (5 micrometres). The NIRCam will also serve as the Observatory's wavefront sensor, which is required for wavefront sensing and control activities. The NIRCam is being built by a team led by the University of Arizona, with Principal Investigator Dr. Marcia Rieke. The industrial partner is Lockheed-Martin's Advanced Technology Center located in Palo Alto, California.
In addition to the near IR imaging capabilities of the NIRCam, the Observatory will also perform spectrography over this range with the NIRSpec (Near InfraRed Spectrograph). The mid IR will be measured by the MIRI (Mid InfraRed Instrument), which contains both a mid IR camera and spectrometer that has a spectral range extending through 27 micrometres. The FGS (Fine Guidance Sensor) is the (non-science) instrument used to stabilize the line-of-sight of the Observatory during science observations.
See also
External links
General Project Links
- JWST homepage at NASA
- JWST homepage at STScI
- JWST homepage at ESA
- Cost overruns put squeeze on Hubble’s successor
Science Instrument Teams