Space observatories
Space observatories and their wavelength working ranges
Space observatories and their wavelength working range
Spitzer, Hubble and XMM with their most important parts depicted

A space observatory is any instrument (such as a telescope) in outer space that is used for observation of distant planets, galaxies and other outer space objects. This category is distinct from other observatories located in space that are pointed toward Earth for the purpose of reconnaissance and other types of information gathering.


Performing astronomy from Earth's surface is limited by the filtering and distortion of electromagnetic radiation (scintillation or twinkling) due to the atmosphere. Some terrestrial telescopes (such as the Very Large Telescope) can reduce atmospheric effects with adaptive optics. A telescope orbiting Earth outside the atmosphere is subject neither to twinkling nor to light pollution from artificial light sources on Earth.

Space-based astronomy is even more important for frequency ranges which are outside the optical window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere. For example, X-ray astronomy is nearly impossible when done from Earth, and has reached its current importance in astronomy only due to orbiting X-ray telescopes such as the Chandra observatory and the XMM-Newton observatory. Infrared and ultraviolet are also greatly blocked.

Space observatories can generally be divided into two classes: missions which map the entire sky (surveys), and observatories which make observations of chosen parts of the sky.

Many space observatories have already completed their missions, while others continue operating, and still others are planned for the future. Satellites have been launched and operated by NASA, ISRO of India, ESA, Japanese Space Agency and the Soviet space program later succeeded by Roskosmos of Russia.


In 1946, American theoretical astrophysicist Lyman Spitzer was the first to conceive the idea of a telescope in outer space, a decade before the Soviet Union launched the first satellite, Sputnik 1.[1]

Spitzer's proposal called for a large telescope that would not be hindered by Earth's atmosphere. After lobbying in the 1960s and 70s for such a system to be built, Spitzer's vision ultimately materialized into the Hubble Space Telescope, which was launched on April 20, 1990 by the Space Shuttle Discovery (STS-31).[2][3]

See also


  1. ^ "Hubble Essentials: About Lyman Spitzer, Jr.". Hubble Site. 
  2. ^ "Hubble Essentials: Quick Facts". Hubble Site. 
  3. ^ "The Hubble Space Telescope". Vic Stathopoulos.