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.
See also: 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.
