Spitzer Space Telescope
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| Spitzer Space Telescope | |
 The Spitzer Space Telescope prior to launch |
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| Organization: | NASA/JPL/Caltech |
|---|---|
| Major contractors: | Lockheed Martin / Ball Aerospace |
| NSSDC ID: | 2003-038A |
| Launched: | August 25, 2003 |
| Launch vehicle: | Delta II 7920H ELV |
| Mass: | 950 kg (2090 lb) |
| Website: | Spitzer Space Telescope |
The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility [SIRTF]) is an infrared space observatory, the fourth and final of NASA's Great Observatories.
The time frame of the mission will be a minimum of 2.5 years, with 5 or more optimal. In keeping with NASA tradition, the telescope was renamed after successful demonstration of operation, on December 18, 2003. Unlike most telescopes which are named after famous deceased astronomers by a board of scientists, the name for SIRTF was obtained from a contest open to the general public (to the delight of science educators).
The name chosen was that of Dr. Lyman Spitzer, Jr., the first to propose placing telescopes in space, in the mid-1940s.
The US$ 800 million[1] Spitzer was launched on Monday 25 August 2003 at 1:35:39 (EDT) from Cape Canaveral Air Force Station on a Delta II 7920H ELV rocket. It follows a rather unusual orbit, heliocentric instead of geocentric, following earth in its orbit, and drifting away from Earth at approximately 0.1 astronomical unit per year (a so-called "earth-trailing" orbit). The primary mirror is 85 cm in diameter, f/12 (i. e. the focal length is 12 times the diameter of the primary mirror) and made of beryllium and cooled to 5.5 K. The satellite contains three instruments that will allow it to perform imaging and photometry from 3 to 180 micrometers, spectroscopy from 5 to 40 micrometers, and spectrophotometry from 5 to 100 micrometers.
Spitzer is the only one of the Great Observatories not launched by the Space Shuttle. It was originally intended to, but after the Challenger disaster, the Centaur LH2/LOX upper stage that would have been required to push it into its intended orbit was banned from Shuttle use. The satellite underwent a series of redesigns during the 1990's, primarily due to budget considerations. This resulted in a much smaller, although still fully capable, mission which could use the smaller Delta launch vehicle. One of the most important aspects of this redesign was the use of the earth-trailing orbit. Cryongenic satellites in earth orbit are exposed to a tremendous heat load from the earth. By placing the satellite in solar, and not earth, orbit, and through the use of innovative passive cooling (such as the sun-shield), the total amount of cryogenic helium needed to cool the satellite was drastically reduced, resulting in an overall smaller, lighter package. This orbit also has the benefit of simplifying the telescope pointing, but does require the Deep Space Network for communications.
The primary instrument package (telescope and cryogenic chamber) was developed by Ball Aerospace & Technologies Corp., in Boulder, CO. 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 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, CA.
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[edit] Instruments
Spitzer has three instruments on-board:
- IRAC (Infrared Array Camera), an infrared camera which operates simultaneously on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm). The resolution is 256 × 256 pixels.
- IRS (Infrared Spectrograph), 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).
- MIPS (Multiband Imaging Photometer for Spitzer), 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)
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 described as trying to observe the stars at noon. Previous space-based satellites (such as IRAS, the Infrared Astronomical Satellite, and ISO, the Infrared Space Observatory) were operational during the 1980s and 1990s and great advances in astronomical technology have been made since then.
[edit] Results
The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe. Since then, monthly press releases have shown off Spitzer's capabilities, as the NASA and ESA images do for the HST. As one of its most noteworthy observations, in 2005, SST became the first to directly capture the light from extrasolar planets, namely the "hot Jupiters" HD 209458b and TrES-1. (It did not resolve that light into actual images though.) [2] This was the first time extrasolar planets had actually been visually seen, and earlier observations had been indirectly made by drawing conclusions from behaviors of the star 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.
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 of 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 System (UW-Madison and UW-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.
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, red shifted by cosmic expansion. [3]
In March of 2006, astronomers reported an 80 light year-long 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 from the nebula and 25,000 light years from Earth. This nebula was discovered by the Spitzer Space Telescope, and published in the magazine Nature on March 16th, 2006.
[edit] Other resources
[edit] See also
[edit] References
- Chadwick H. Young, Jes K. Jørgensen, Yancy L. Shirley, Jens Kauffmann, Tracy Huard, Shih-Ping Lai, Chang Won Lee, Antonio Crapsi, Tyler L. Bourke, Cornelis P. Dullemond, Timothy Y. Brooke, Alicia Porras, William Spiesman, Lori E. Allen, Geoffrey A. Blake, Neal J. Evans II, Paul M. Harvey, David W. Koerner, Lee G. Mundy, Phillip C. Myers, Deborah L. Padgett, Anneila I. Sargent, Karl R. Stapelfeldt, Ewine F. van Dishoeck, Frank Bertoldi, Nicholas Chapman, Lucas Cieza, Christopher H. DeVries, Naomi A. Ridge, and Zahed Wahhaj (2004). "A "starless" core that isn't: Detection of a source in the L1014 dense core with the Spitzer Space Telescope". Astrophysical Journal Supplement 154 (September): 396-401 Abstract.
[edit] External links
- Spitzer images: http://www.spitzer.caltech.edu/Media/mediaimages/index.shtml
- Spitzer newsroom: http://www.spitzer.caltech.edu/Media/index.shtml
- Spitzer podcasts: http://www.spitzer.caltech.edu/features/podcasts/index.shtml
- Spitzer video podcasts: http://www.spitzer.caltech.edu/features/hiddenuniverse/index.shtml
