Space observatory

Hubble Space Telescope.

James Webb Space Telescope.

A space observatory, also known as a space telescope, is an artificial satellite or space probe used to observe planets, stars, galaxies and other celestial bodies similar to a telescope on the ground. A significant number of space telescopes have been launched into orbit since Cosmos 215, considered the first space observatory, was launched on April 18, 1968, providing greater information and knowledge of the cosmos.

There are several reasons why observing from space is desirable, because it avoids some of the problems that ground-based observatories have. The benefits of space observatories are:

• A telescope in space does not suffer the light pollution produced by nearby cities. In addition, it is not affected by the thytilar produced due to the thermal turbulences of the air.
• The Earth's atmosphere adds an important distortion in the images, known as optical aberration. The resolution capacity of the Earth telescopes is significantly reduced. A space telescope does not observe through the atmosphere, so its capacity always yields close to the theoretical maximum. This problem for ground telescopes has been partially solved with the use of adaptive optics, such as the Very Large Telescope, but they are complex and do not solve the problem completely.
• The atmosphere also absorbs an important portion of the electromagnetic spectrum, so some observations are practically impossible to make from the ground. X-ray astronomy is not performed from Earth, but from space telescopes such as Chandra or XMM-Newton. Other portions of the electromagnetic spectrum, such as infrared waves or ultraviolet waves, are also filtered by the atmosphere.

Space telescopes, however, also suffer from some disadvantages that ground-based observatories do not:

• High cost, mainly in launch. Costs for using a medium-sized rocket can reach $250 million, and using the space shuttle doubles that price.
• The impossibility of maintenance. Except the Hubble space telescope, which has received maintenance from space shuttle missions, if a space observatory does not work, it cannot be replaced.
• Short life. Most of the space telescopes should be refrigerated and when the cooling fluids are finished, the tank cannot be filled with new liquid. However, space telescopes do not need periodic maintenance as it is not affected by conditions under atmosphere.

Space observatories can be divided into two general classes: those whose mission is to survey the entire sky, and telescopes that only make observations of selected parts of the sky. Many of the space observatories have already completed their missions, while others are up and running. Satellites and space probes for astronomical observation have been launched by NASA, ESA, and JAXA.

NASA's Great Observatories

Comparison between space telescopes by diameter

NASA's Great Observatories series are four high-powered space telescopes. Each telescope has had a similar cost and have served to expand knowledge in astronomy. All four missions have examined a part of the electromagnetic spectrum for which they were designed.

• Hubble Space Telescope (in English, Hubble Space Telescope o HST) previously known as Space Telescope (ST). It mainly observes the area of the visible spectrum and the area of the near ultraviolet. It was launched into space on 24 April 1990 and is a joint project between NASA and ESA. A 1997 space shuttle service mission provided him with the ability to observe near infrared.
• Gamma Compton Ray Observatory (Gamma ComptonCompton Gamma Ray Observatory o CGRO) previously known as Gamma Ray Observatory (GRO). It was mainly gamma rays, but also hard x-rays. His gyroscopes began to fail so he had to choose between leaving him unchecked or destroying him. The latter was chosen and the Pacific Ocean fell on 4 June 2000.
• Chandra X-ray ObservatoryChandra X-ray Observatory o CXO) previously known as Advanced X-ray Astronomical Facility (AXAF). It mainly observes soft X-rays. It has been used for the study of distant galaxies and remains operational.
• Spitzer Space TelescopeSpitzer Space Telescope o SST) previously known as Space Infrared Telescope Facility (SIRTF). Watch the infrared spectrum. It is the last and was launched on August 24, 2003.

Other space observatories

Classification of space observatories by area of the electromagnetic spectrum.

• IRAS, who performed the first complete tracing in infrared from the sky, as well as discovering dust and gas disks in many nearby stars such as Fomalhaut, Beta Pictoris and Vega. It stopped working in 1983 and was destroyed by reentering the atmosphere.
• Astron, an ultraviolet telescope of the former USSR. It worked from 1983 to 1989.
• Granat, an X-ray telescope and Soviet gamma rays. It worked from 1983 to 1998.
• Infrared or ISO Space Observatory, a mission of the European Space Agency, following the IRAS and carried out observations in infrared wavelengths.
• Corot, a French Space Agency and ESA mission launched in December 2006. This is the first mission to search for rocky planets around other stars.
• International Ultraviolet Explorer or IUE, a NASA, ESA and the UK observatory that was launched in 1978 with a planned life of three years, although it worked until 1996.
• SOHO, a solar observatory that continues to work and is used for the study of the solar corona and magnetic zones.
• SCISAT-1, a Canadian satellite observing the upper part of the Earth's atmosphere with an infrared spectrometer.
• Uhuru, the first X-ray space observatory. It was launched on 12 December 1970, operating until 1973.
• HEAO-1 and HEAO-2, X-ray observatories of 1977 and 1978 respectively.
• Hipparcos, a satellite to measure the stellar parallax. Despite his operating problems, he checked the distance to the variable star Cefeida with great precision.
• MOST, the first and only space telescope of the Canadian Space Agency, launched in 2003, is the smallest space telescope in the world of 63 cm high and 53 kg weight. It's expected to work at least five years.
• ASTRO-F, built by the Japanese Aerospace Exploration Agency, with collaboration from Koreans and Europeans, was launched in February 2006 and will carry out a deep map of the sky in mid and far infrared.
• Swift, an observatory dedicated to the study of gamma or GRB rays explosions launched in 2004.
• INTEGRAL, an ESA observatory launched on 17 October 2002 for the detection of energy radiation from space. This is the most sensitive gamma-ray observatory until now launched.
• WMAP or Wilkinson Microwave Anisotropy ProbeIt's a NASA mission to record the temperature that exists in microwave background radiation. It was launched on 30 June 2001.

Projected space observatories

• The James Webb Space Telescope, which will replace the Hubble Space Telescope.
• The Atlas Space Telescope, being studied by NASA.
• The ACESat, being studied by NASA, for the search for habitable planets in the Alpha Centauri system.
• The Chinese Xuntian space telescope, which can be coupled with the large Chinese space station.