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About SOFIA |
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More...
You can find scientific and technical information on the telescope
under
Info for Researchers
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DLR,
in partnership with NASA on the SOFIA project,
is responsible for
the telescope assembly
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Home > About
SOFIA > SOFIA Telescope
SOFIA
Telescope |
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Click on image for enlarged view. |
Like most modern research
telescopes, the SOFIA telescope uses a mirror to concentrate
and focus the incoming
light. When it comes to large telescopes, mirror-based systems
(called "reflectors") have proven to be much more
practical than lens-based telescopes (called "refractors")
because they are much easier and less expensive to build
and
use.
SOFIA’s primary
mirror, located near the bottom of the telescope, is 2.7
meters (almost 9 feet) across.
The front surface, which is highly polished and then coated
with Aluminum to ensure maximum reflectivity, is deeply
concave
(dished inward). Incoming light rays bounce off the curved
surface and are all deflected inward at the same time they
are reflected back up toward the front of the telescope.
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| Before the light reaches the telescope’s
front end, however, it is intercepted by a small secondary mirror
(about .4 meters across), which sends the light back down toward
the center of the main mirror. About a meter above the center
of the main mirror, a third mirror sends the light out through
the side of the telescope, down a long tube which projects through
the main aircraft bulkhead into the interior of the SOFIA aircraft.
There, at the telescope’s focal point, the light will be
recorded and analyzed by one of several different instruments. |
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| The SOFIA telescope's main support structure
being tested in Augsburg Germany in October, 2001. Photo
courtesy Man Technologie. Click on image for enlarged
view. |
Astronomers tend to compare telescopes
based on the diameter of their primary mirrors. SOFIA’s telescope
is usually referred to as a 2.5-meter meter telescope, rather
than 2.7 meters, because the optical design requires that only
about 90% of the mirror’s reflecting surface (called the
"effective aperture") can be used at any one time.
Although SOFIA’s telescope is by far the largest ever to
be placed in an aircraft, compared to normal ground-based research
observatories it is only medium-sized (the world’s largest
single-mirror telescope, the Subaru, is 8.2 meters across).
International Cooperation
Under an international agreement between
the United States and the German governments, the SOFIA telescope
is being supplied by the German
Aerospace Center (DLR). DLR is supplying the
telescope and additional operation support in return for
a portion of SOFIA's valuable observing time.
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Page Last Updated:
February 19, 2004
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