DesertFox
02-07-2005, 07:19 AM
The Observatory
From a remote outpost on the summit of Hawaii's dormant Mauna Kea volcano, astronomers
at the W. M. Keck Observatory probe the deepest regions of the Universe with unprecedented
power and precision.
http://www2.keck.hawaii.edu/geninfo/noroof1.jpg
Their instruments are the twin Keck Telescopes, the world's largest optical and
infrared telescopes. Each stands eight stories tall and weighs 300 tons, yet operates
with nanometer precision. At the heart of each Keck Telescope is a revolutionary
primary mirror. Ten meters in diameter, the mirror is composed of 36 hexagonal segments
that work in concert as a single piece of reflective glass. ...
The Telescopes
An altitude-azimuth design gives each 10-meter Keck telescope the optimal balance
of mass and strength. Extensive computer analysis determined the greatest strength
andstiffness for the least amount of steel– about 270 tons per telescope. This is
critically important, and not only for economic reasons. A large telescope must remain
resistant to the deforming forces of gravity as it tracks objects moving across the night
sky.
Chilling the interior of the insulated dome during the day controls temperature variations
that could induce deformation of the telescope’s steel and mirrors. This is a big task:
The volume of each dome is more than 700,000 cubic feet. Giant air conditioners
run constantly during the day, keeping the dome temperature at or below freezing.
http://www2.keck.hawaii.edu/geninfo/images/mastroianni_sunset.gif
Astronomers use the telescopes in shifts of one to five nights. Time allocation committees
pre-approve all observing. Assistants operate the telescopes at the summit while
astronomers gather data via remote observing from observatory headquarters in Waimea.
The W. M. Keck Observatory was the first facility on Mauna Kea to use remote observing. ...
The Primary Mirror
A telescope tracks objects, sometimes for hours, across the sky as the Earth turns.
This constant but subtle movement results in slight deformations of the telescope
structure despite all engineered precautions. Without active, computer-controlled
correction of the primary mirror, scientific observations would be impossible.
New techniques for manufacturing, polishing, and testing the mirror segments had to
be invented, including “stressed mirror” polishing. Each segment’s surface is so smooth
that if it were the width of Earth, imperfections would be only three feet high.
http://www2.keck.hawaii.edu/images/1.jpg
On the telescope, each segment’s figure is kept stable by a system of extremely
rigid support structures and adjustable warping harnesses. During observing, a computer-
controlled system of sensors and actuators adjusts the position of each segment –
relative to its neighbors – to an accuracy of four nanometers, about the size of a few
molecules, or about 25,000 times thinner than a human hair. This twice-per-second
adjustment effectively counters the tug of gravity. ...
More (http://www2.keck.hawaii.edu/geninfo/about.php)
From a remote outpost on the summit of Hawaii's dormant Mauna Kea volcano, astronomers
at the W. M. Keck Observatory probe the deepest regions of the Universe with unprecedented
power and precision.
http://www2.keck.hawaii.edu/geninfo/noroof1.jpg
Their instruments are the twin Keck Telescopes, the world's largest optical and
infrared telescopes. Each stands eight stories tall and weighs 300 tons, yet operates
with nanometer precision. At the heart of each Keck Telescope is a revolutionary
primary mirror. Ten meters in diameter, the mirror is composed of 36 hexagonal segments
that work in concert as a single piece of reflective glass. ...
The Telescopes
An altitude-azimuth design gives each 10-meter Keck telescope the optimal balance
of mass and strength. Extensive computer analysis determined the greatest strength
andstiffness for the least amount of steel– about 270 tons per telescope. This is
critically important, and not only for economic reasons. A large telescope must remain
resistant to the deforming forces of gravity as it tracks objects moving across the night
sky.
Chilling the interior of the insulated dome during the day controls temperature variations
that could induce deformation of the telescope’s steel and mirrors. This is a big task:
The volume of each dome is more than 700,000 cubic feet. Giant air conditioners
run constantly during the day, keeping the dome temperature at or below freezing.
http://www2.keck.hawaii.edu/geninfo/images/mastroianni_sunset.gif
Astronomers use the telescopes in shifts of one to five nights. Time allocation committees
pre-approve all observing. Assistants operate the telescopes at the summit while
astronomers gather data via remote observing from observatory headquarters in Waimea.
The W. M. Keck Observatory was the first facility on Mauna Kea to use remote observing. ...
The Primary Mirror
A telescope tracks objects, sometimes for hours, across the sky as the Earth turns.
This constant but subtle movement results in slight deformations of the telescope
structure despite all engineered precautions. Without active, computer-controlled
correction of the primary mirror, scientific observations would be impossible.
New techniques for manufacturing, polishing, and testing the mirror segments had to
be invented, including “stressed mirror” polishing. Each segment’s surface is so smooth
that if it were the width of Earth, imperfections would be only three feet high.
http://www2.keck.hawaii.edu/images/1.jpg
On the telescope, each segment’s figure is kept stable by a system of extremely
rigid support structures and adjustable warping harnesses. During observing, a computer-
controlled system of sensors and actuators adjusts the position of each segment –
relative to its neighbors – to an accuracy of four nanometers, about the size of a few
molecules, or about 25,000 times thinner than a human hair. This twice-per-second
adjustment effectively counters the tug of gravity. ...
More (http://www2.keck.hawaii.edu/geninfo/about.php)