Space telescope, definition and study. A-Z index of Cognitio.

A space telescope is a satellite or a spatial probe launched with the express purpose of observing planets, stars, galaxies, and other celestial objects, just like a ground-based telescope.

Numerous space telescopes have been launched, which have greatly contributed to our knowledge of the cosmos. The motive behind the observation of space is that it does not suffer from many problems that it has observation from the surface of the Earth, in an increasing order of importance:

  • a telescope in the space does not suffer from the light pollution caused by neighboring countries and cities
  • the Earth’s atmosphere introduces considerable distortion in the images (properly called optical aberration).
    Atmosphere, definition and study. A-Z index of Cognitio.

    Atmosphere

    The resolution capability of large terrestrial telescopes is therefore greatly reduced. An observatory in space must not look through miles of atmosphere, and always has close performance to its theoretical maxim. This problem is now also partially solved by adaptive optics techniques, but they are complex and do not completely solve the problem.

  • the atmosphere also absorbs a large portion of the electromagnetic spectrum, preventing the radiation of many celestial objects from reaching us. Many observations are therefore simply impossible from the ground, and it is necessary to move out of the atmosphere to lead them.

Space telescopes, however, suffer some disadvantages as compared to their earthly cousins:

  • very high cost, especially for launching: renting an average rocket can cost 200 million Euros, and the Shuttle cost more than double.
  • maintenance is impossible, if the telescope fails can not be replaced.
  • short operating life: many telescopes need to be cooled, and when the cooling liquid ends, the tank can not be filled again. In addition, even telescopes that do not require periodic maintenance end up succumbing to the harsh conditions of the space environment (hot and cold intensities, hard radiation that ruin the electronics, etc). Another common cause is the exhaustion of the funds available for the mission, which are used to pay ground staff and the expensive Deep Space Network antennas that maintain effective contact with the satellite.

Observational spatial missions can be divided into two large classes: those that try to map the entire sky and those look only for small portions selected, but at much greater resolution. Space telescopes can be classified in:

Gamma rays

The gamma ray telescopes detect gamma ray emissions from cosmic springs. Such emissions are absorbed by the Earth’s atmosphere and therefore observations require spatial telescopes or high-altitude balloons. Gamma rays can be generated by supernovae, neutron stars, pulsars and black holes. Telescopes can also detect gamma such as the latest generation, the Swift Gamma Ray Burst Explorer telescope.

Swift Gamma Ray Burst Explorer telescope

Swift Gamma Ray Burst Explorer telescope

X-ray

X-rays can not penetrate much into the Earth’s atmosphere, meaning that they can only be observed from high altitudes or from space. Different kinds of astronomical objects can emit X-rays, galaxies, active galactic nuclei, supernovae remains, stars and some binary stars, those containing a white dwarf, a neutron star or a black hole. Even some objects in the solar system emit X-rays, the most well known being the Moon, although most of the X-ray from the Moon is the reflection of the solar ones. There is also a X-ray bottom that is believed to be dependent on a combination of non-known X-ray sources. In 2021 NASA / ESA / JAXA will arrive at the new generation of telescopes of this type, called the International X-ray Observatory (IXO).

X-ray Observatory (IXO)

X-ray Observatory (IXO)

 

Ultraviolet

These telescopes perform observations in the ultraviolet wavelength. The light at these wavelengths is absorbed by the Earth’s atmosphere, so observations must be made either by the high atmosphere or the space. Among the objects that emit ultraviolet radiation there are the Sun, the other stars and the galaxies. The latest telescope in age order is Galaxy Evolution Explorer (GALEX)

Galaxy Evolution Explorer (GALEX)

Galaxy Evolution Explorer (GALEX)

Visible

Placing an optical telescope in the space means not to be atmospheric due to turbulence and temperature, providing higher resolution images. Optical telescopes are used to observe stars, galaxies, nebula, protoplanets disks and many other objects. Of the next generation, but not yet announced the date of the presentation is the new Terrestrial Planet Finder.

Terrestrial Planet Finder

Terrestrial Planet Finder

 

Infrared

Many astronomical objects are too cold and weak to be observable in visible light, so it is used to observe infrared radiation. At the infrared it is possible to study the stars (including the dark dwarf cold), the nebulae and the galaxies moved to the red. The next launch in 2018 concerns the latest generation of infrared telescopes called the James Webb Space Telescope.

James Webb Space Telescope

James Webb Space Telescope

 

Microwave

At microwave frequencies the photons are abundant, but they also have very low energies, so you need to collect many. At these frequencies, you can measure the cosmic background radiation. The last in order of age is the Planck Surveyor.

Planck Surveyor

Planck Surveyor

 

Radio

Since the Earth’s atmosphere is transparent to radio waves, space-based radio telescopes are mainly used by simultaneous observations from satellite and ground to correlate and simulate a radio telescope as large as the separation between the two. With radio waves you can observe supernovae remains, gravitational lenses, celestial maters, starburst galaxies and many more. The RadioAstron telescope is still in circulation.

RadioAstron telescope

RadioAstron telescope

 

Particle detectors

Particulate satellites look for cosmic and electron beams. These can be emitted by the Sun (solar energy particles), our galaxy (galactic cosmic rays) and extra-galactic sources (extra-galactic cosmic rays). There are also ultra-energetic cosmic rays coming from active galactic nuclei. Finally, the Payload for Antimatter Matter Exploration and Light-Core Astrophysics (PAMELA).

Payload for Antimatter Matter Exploration and Light-Core Astrophysics (PAMELA)

Payload for Antimatter Matter Exploration and Light-Core Astrophysics (PAMELA)

 

Gravitational waves

A new type of space telescope has been proposed to detect gravitational waves, ripples in space-time generated by the neutron stars collision and black holes. With 2018 launch of the Laser Interferometer Space Antenna (LISA).

Interferometer Space Antenna (LISA)

Interferometer Space Antenna (LISA)

 

Space telescope, definition and study. A-Z index of Cognitio.

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Space telescope, definition and study. A-Z index of Cognitio.

Space telescope