An Etymological Dictionary of Astronomy and Astrophysics
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An infrared telescope launched by NASA on 25 August 2003, the last in the series of Great Observatories. It was placed into a heliocentric orbit with a period of revolution that causes it to drift away from Earth at a rate of 0.1 → astronomical unit per year. Spitzer has a 85-cm primary mirror, made of beryllium and is equipped with three cryogenically-cooled science instruments: 1) IRAC (Infrared Array Camera), which operates simultaneously on four wavelengths (3.6, 4.5, 5.8, and 8 µm); 2) IRS (Infrared Spectrograph), 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); and 3) MIPS (Multiband Imaging Photometer for Spitzer), three detector arrays in the → far infrared at 24, 70, and 160 µm. So far Spitzer has obtained precious data on all sorts of astronomical objects, thus contributing to all fields of astrophysics. It has also performed two sky surveys: GLIMPS, which covers 300° of the inner Milky Way galaxy, consisting of approximately 444,000 images taken at 4 separate wavelengths with the IRAC, and MIPSGAL a similar survey covering 278° of the Galactic disk at longer wavelengths.The planned nominal 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, most instruments are no longer usable. However, the two shortest wavelength modules of the IRAC camera are still operable and will continue to be used in the Spitzer Warm Mission.

Named in honor of Lyman Spitzer (1914-1997), an American theoretical physicist and astronomer best known for his research in star formation and plasma physics, who first suggested (1940s) placing telescopes in orbit to escape interference from the Earth's atmosphere; → space; → telescope.