Date: 14 Dec 2006 16:37:24
From: Rich
Subject: $75M to determine feasibility of a 42m (1600") telescope
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>From Photonics.com
http://www.photonics.com/content/news/2006/December/12/85345.aspx
ESO Approves 'Extremely Large Telescope' Study
GARCHING, Germany, Dec. 12, 2006 -- The ESO Council, the governing body
of the Garching-based European Southern Observatory (ESO), has
authorized detailed studies for the European Extremely Large Telescope.
The 57 million euro (approximately $75.4 million) studies will make it
possible to start construction in three years on the optical/infrared
telescope that officials said will revolutionize ground-based
astronomy.
"The decision by the ESO Council to go ahead with the design study for
a European Extremely Large Telescope is a very exciting one for
European astronomy," said Richard Wade, president of the ESO Council.
EuropeanELT.jpgAn artist's impression of the European Extremely Large
Telescope provides a bird's-eye view of the structure, which features a
42-m diameter primary mirror -- its total rotating mass is 5500 tons --
and two platforms on each side of the structure to hold large
instruments. The telescope's novel design is based on five mirrors and
results in exceptional image quality with no significant aberrations in
the field of view. To gauge the size of the telescope, note the two
people and the car in the bottom left-hand corner of the image. (Image:
ESO) Extremely Large Telescopes are considered worldwide as one of the
highest priorities in ground-based astronomy. They will vastly advance
astrophysical knowledge, allowing detailed studies of subjects
including planets around other stars, the first objects in the
Universe, supermassive black holes, and the nature and distribution of
the dark matter and dark energy which dominate the Universe.
The ESO Council represents 11 European countries (Belgium, Denmark,
France, Finland, Germany, Italy, the Netherlands, Portugal, Sweden,
Switzerland and the United Kingdom; Spain is expected to become a full
member before the end of 2006), accounting for most of the astronomical
investment capabilities of Europe. Since the end of last year, ESO has
been working with its user community of more than 100 European
astronomers and astrophysicists to define the new giant telescope
needed by the middle of the next decade, taking into account
performance, cost, schedule and risk.
The project has moved quickly thanks to early conceptual studies done
in Europe and research and development done in collaboration with a
large number of European institutes and high-tech industries, officials
said.
Provisionally dubbed E-ELT for the European Extremely Large Telescope,
ESO's concept was presented in detail two weeks ago to more than 250
European astronomers at a conference in Marseille, France. Their
enthusiastic response to the project, officials said, paved the way for
the decision by the ESO Council to move to the crucial next phase:
detailed design of the full facility.
"At the end of the three-year Final Design Study, we will know exactly
how everything is going to be built, including a detailed costing,"
said Catherine Cesarsky, ESO's director general. "We then hope to start
construction and have it ready by 2017, when we can install instruments
and use it."
The present concept, estimated to cost around 800 million euro
(approximately $1 billion), features as a baseline a telescope with a
42-m diameter mirror, and is revolutionary.
"A telescope of this size could not be built without a complete
rethinking of the way we make telescopes," Cesarsky said.
The primary 42-m diameter mirror is composed of 906 hexagonal segments,
each 1.45 m in size, while the secondary mirror is as large as 6 m in
diameter. In order to overcome the fuzziness of stellar images due to
atmospheric turbulence, the telescope needs to incorporate adaptive
mirrors into its optics. Post-focal adaptive optics, i.e. optics built
into the instruments and not in the telescope design itself, is a
technology present in seven adaptive optics (AO) systems and a laser
guide star in operation at the ESO's Very Large Telescope (VLT) at the
Paranal Observatory in Atacama, Chile. VLT is currently the world's
largest and most advanced optical telescope, consisting of four 8.2-m
reflecting unit telescopes and several moving 1.8-m auxiliary
telescopes. The VLT produces extremely sharp images and can record
light from the faintest and most remote objects in the Universe.
A tertiary mirror, 4.2 m in diameter, relays the light to the AO
system, composed of two mirrors: a 2.5-m mirror supported by 5000 or
more actuators able to distort its own shape a thousand times per
second, and one 2.7 m in diameter that allows for the final image
corrections. This five-mirror approach results in an exceptional image
quality, with no significant aberrations in the field of view.
With a diameter of 42-m and its AO concept, the E-ELT will be more than
100 times more sensitive than the present-day largest optical
telescopes, such as the 10-m Keck telescopes or the 8.2-m VLT
telescopes.
"This is really the beginning of a new era for optical and infrared
astronomy," Cesarsky said.
The site of the E-ELT has not been determined; officials expect to make
a decision by 2008.
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