Overwhelmingly Large Telescope
Encyclopedia
The Overwhelmingly Large Telescope (OWL) is a conceptual design by the European Southern Observatory
(ESO) organization for an extremely large telescope
, which was intended to have a single aperture of 100 meters in diameter. Because of the complexity and cost of building a telescope of this unprecedented size, ESO has elected to focus on the 39 meter diameter European Extremely Large Telescope instead.
While the original 100-m design would not exceed the angular resolving power of interferometric telescopes
, it would have exceptional light-gathering and imaging capacity which would greatly increase the depth to which humankind could explore the universe. The OWL could be expected to regularly see astronomical objects with an apparent magnitude
of 38; or 1,500 times fainter than the faintest object which has been detected by the Hubble Space Telescope
.
All proposed designs for the OWL are variations on a segmented mirror
, since there is no technology available to build a monolithic 60- or 100-meter mirror. The operation of a segmented mirror is somewhat more complicated than a monolithic one, requiring careful alignment of the segments (a technique called cophasing
). Experience gained in existing segmented mirrors (for example, the Keck telescope) suggests that the mirror proposed for the OWL is feasible. However, the projected cost (of around €1.5 billion) was uncomfortably high, and the ESO is now working on a smaller European Extremely Large Telescope around 42 m in diameter.
It has been estimated that a telescope with a diameter of 80 meters would be able to spectroscopical
ly analyse Earth-size planets around the 40 nearest sun-like stars. As such, this telescope could help in the exploration of extrasolar planets and extraterrestrial life
(because the spectrum from the planets could indicate the presence of molecules indicative of life).
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
(ESO) organization for an extremely large telescope
Extremely large telescope
An extremely large telescope is an astronomical observatory featuring a telescope with an aperture of more than 20 m diameter when discussing reflecting telescopes of optical wavelengths including ultraviolet , visible, and near infrared wavelengths. Among many planned capabilities, ELTs are...
, which was intended to have a single aperture of 100 meters in diameter. Because of the complexity and cost of building a telescope of this unprecedented size, ESO has elected to focus on the 39 meter diameter European Extremely Large Telescope instead.
While the original 100-m design would not exceed the angular resolving power of interferometric telescopes
Astronomical interferometer
An astronomical interferometer is an array of telescopes or mirror segments acting together to probe structures with higher resolution by means of interferometry....
, it would have exceptional light-gathering and imaging capacity which would greatly increase the depth to which humankind could explore the universe. The OWL could be expected to regularly see astronomical objects with an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of 38; or 1,500 times fainter than the faintest object which has been detected by the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
.
All proposed designs for the OWL are variations on a segmented mirror
Segmented mirror
A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be either spherical or asymmetric . They are used as objectives for large reflecting telescopes...
, since there is no technology available to build a monolithic 60- or 100-meter mirror. The operation of a segmented mirror is somewhat more complicated than a monolithic one, requiring careful alignment of the segments (a technique called cophasing
Cophasing
In astronomy, the term cophasing or phasing describes the process of controlling the individual segments in a segmented mirror or a telescope so that the segments form a larger composite mirroring surface...
). Experience gained in existing segmented mirrors (for example, the Keck telescope) suggests that the mirror proposed for the OWL is feasible. However, the projected cost (of around €1.5 billion) was uncomfortably high, and the ESO is now working on a smaller European Extremely Large Telescope around 42 m in diameter.
It has been estimated that a telescope with a diameter of 80 meters would be able to spectroscopical
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
ly analyse Earth-size planets around the 40 nearest sun-like stars. As such, this telescope could help in the exploration of extrasolar planets and extraterrestrial life
Extraterrestrial life
Extraterrestrial life is defined as life that does not originate from Earth...
(because the spectrum from the planets could indicate the presence of molecules indicative of life).
See also
- Active opticsActive opticsActive optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, mechanical stress...
- Adaptive opticsAdaptive opticsAdaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
- European Extremely Large Telescope
- Extremely Large TelescopeExtremely Large TelescopeThe European Extremely Large Telescope is a ground-based extremely large telescope featuring an optical/near-infrared telescope of large size and advanced features that is being planned by the European Southern Observatory...
- Giant Magellan TelescopeGiant Magellan TelescopeThe Giant Magellan Telescope is a ground-based extremely large telescope planned for completion in 2018. It will consist of seven diameter primary segments, with the resolving power of a primary mirror and collecting area equivalent to one...
- List of optical telescopes
- Thirty Meter TelescopeThirty meter telescopeThe Thirty Metre Telescope is a proposed ground-based large segmented mirror reflecting telescope to be built on Mauna Kea in Hawaii. The telescope is designed for observations from the near-ultraviolet to the mid-infrared . An adaptive optics system would correct for image blur caused by the...
External links
- The ESO 100-m optical telescope concept
- OWL BLUE BOOK – Phase A design report
- ThinnedAperture Telescope], hundred meter aperture space telescope concept