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. 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 primary instrument package was developed by
Ball Aerospace, in
Boulder, CO.
* IRAC (
Infra
red
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 (
Infra
red
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, 20 × 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. This necessitates lengthy calibrations of all images and will decrease the ability to detect faint objects. 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.
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
Hubble Heritage 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; the "hot Jupiter" planets
HD 209458b and TrES-1 respectively. [
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.
 |
Clockwise from the upper-left: Infrared views of spiral galaxy Messier 81; Embedded outflows from Herbig-Haro 46/47 protostar; Protostars uncovered in multiple views of dark globule in IC1396; and Comet Schwassmann-Wachmann 1. |
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 (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.
 |
Valentine's Day release: These bright young stars are found in a rosebud-shaped (and rose-colored) nebulosity known as NGC 7129. The star cluster and its associated nebula are located at a distance of 3300 light-years in the constellation Cepheus. |
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]
|
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. |
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.
See also
*
Space telescope*
Great Observatories programReferences
*
External links
*
Spitzer official site *
Simulation of Spitzer's orbit
