Home > Space observatory

1 Introduction

A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos. Performing astronomy from the Earth's surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth's atmosphere. This makes it desirable to place astrononomical observation devices into space. As a telescope orbits the Earth outside the atmosphere it is neither subject to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth. Some terrestrial telescopes (such as the Very Large Telescope) can counter turbulences with the help of its novel adaptive optics.

But space-based astronomy is even more important for frequency ranges which are outside of the optic 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 the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory. InfraredInfrared IR radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra "below"), red being the color of visible light of longest wavelength. and ultravioletNote: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. Ultraviolet UV radiation is electromagnetic radiation of a wavelength shorter than that of visible light, but longer than that of soft X-rays. It can be subdivided into 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 are still operating. Satellites have been launched by NASAThe National Aeronautics and Space Administration NASA (established 1958) is the government agency responsible for the United States of America's space program and long-term general aerospace research. A civilian organization, it conducts (or oversees) re, ESAThis article is about the European Space Agency. See Entertainment Software Association for another meaning of ESA. The European Space Agency ESA is an inter-governmental organisation dedicated to exploration of space and its exploitation. Its headquarter and JapanJapan (, Nippon/Nihon literally "the origin of the sun") is a country in East Asia situated on a chain of islands east of the Asian continent on the western edge of the Pacific Ocean. The largest of these islands are, from north to south, Hokkaido , Honsh space agency.

2 NASA's Great Observatories

Satellites belonging to NASA's "Great Observatories" program:

• The Space Telescope (ST), now known as Hubble Space TelescopeHubble Space Telescope Space Shuttle Discovery during the second servicing mission of the telescope, STS-82 Organization NASA, ESA Wavelength regimeoptical Orbit height600 km Orbit period100 min Launch date 24 April 1990 Deorbit datecirca 2010 Mass11,000 (HST) is the optical Great Observatory. It was launched to great acclaim and soon after discovered to be flawed. Its main mirrorThis article is about the reflective surfaces. A mirror is a reflective surface that is smooth enough to be able to form an image. The best known example is the plane mirror that most people have at home. In it, a parallel beam of light changes its direct contained imperfections in its grinding that resulted from a certain production limitation being accounted for twice. It has now been fitted with the equivalent of spectacles to compensate for this.

• The Gamma ray Observatory (GRO), since renamed to The Compton Gamma-Ray Observatory, had to be disposed of after several years of productive life. Its gyroscopes began to fail and when it was down to its last gyroscope, the choice was to risk losing control or destroying the observatory. NASA ditched the bus-sized satellite into the Pacific Ocean in 2000.

• X-Rays are also represented in the Great Observatories, with the Chandra X-ray Observatory, renamed (from AXAF) in honor of the great Indian astrophysicist Chandrasekhar. This has been used to great effect to study distant galaxies and is still operational.

• The Spitzer Space Telescope is the fourth observatory, originally called the Space Infrared Telescope Facility, SIRTF, launched on August 24, 2003.