From
Sky & Telescope (emphasis added): Dec 19 2003
This Spitzer Space Telescope composite image shows the primary components of galaxy Messier 81 (top), in Ursa Major. Old stars predominate in the central portion of the galaxy, while the graceful spiral arms are dominated by infrared emission from dust. Massive stars are being born in the bright clumps within the spiral arms. The composite picture is made from images in 3.6, 8.0, and 24 microns, which are colored red, green, and blue, respectively (below). Courtesy NASA/JPL/Caltech/K. Gordon (University of Arizona) and S. Willner (Harvard-Smithsonian Center for Astrophysics), N.A. Sharp (NOAO/AURA/NSF).
December 19, 2003 | Astronomers have embarked upon a new era brimming with never-before-seen celestial objects and new views of classic astronomical marvels. That was the message sent to the public on December 18th as NASA released the first scientific images from the Space Infrared Telescope Facility (SIRTF), now called the Spitzer Space Telescope. As one principal investigator remarked, "We can expect a flood of discoveries over the next five years."
Unlike the Hubble Space Telescope, which is tuned to see the cosmos in visible light (with some spillover into the near-infrared and near-ultraviolet), Spitzer is an infrared-only telescope. This affords it the opportunity to see things never seen before in astronomy. Most notably, dust clouds are often opaque to visible or near-infrared light. But Spitzer, looking in lower-energy wavelengths, can see through the dusty cloak, unveiling the mysteries that lie beneath. These treasures include newly forming planets and the shrouded birthing rooms of stars and galaxies.
Spitzer will detect and discern the feeble heat coming from objects vast distances away. To do so the entire instrument is cryogenically cooled with liquid helium to 5.5° Kelvin (–268°C). Unfortunately, the spacecraft carries only a fixed amount of coolant on board, thus limiting its expected lifetime to just 5.8 years — double the expected lifespan at launch. Moreover, Spitzer cannot be serviced. It resides in an Earth-trailing orbit, slowly drifting from our planet with each passing day. As such, space shuttles can't reach it.
The last of NASA's four Great Observatories (its sister scopes are the Hubble Space Telescope, Compton Gamma-Ray Observatory, and Chandra X-ray Observatory), the Spitzer Space Telescope hosts a trio of powerful instruments: the Infrared Array Camera (IRAC) will observe simultaneously in four wavelengths centered at 3.6, 4.5, 5.8, and 8.0 microns; the Multiband Imaging Photometer for Spitzer (MIPS) can do both photometric mapping and high-resolution imaging at 24, 70, and 160 microns; and an Infrared Spectrograph (IRS) that will take spectral images from 5.3 to 40 microns.
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More:
http://skyandtelescope.com/news/article_1129_1.asp(EDIT: Put image into a link, since it wasn't coming up properly for me. But do look at it! :-) )
(EDIT AGAIN: Put image back in directly. :shrug: )
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