Space observatory

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Space observatories
The Hubble Space Telescope, one of the Great Observatories.

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. The first such space observatory was the Hubble Space Telescope launched in 1990. Space observatories avoid many of the problems of ground observatories, such as light pollution and the filtering and distortion of electromagnetic radiation (scintillation).

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.


Spitzer, Hubble and XMM with their most important parts depicted

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 24, 1990 by the Space Shuttle Discovery (STS-31).[2][3]


rightSpace observatories and their wavelength working ranges

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.

Space observatories and their wavelength working range

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, ESA, Japanese Space Agency and the Soviet space program later succeeded by Roskosmos of Russia.

See also[edit]