WASHINGTON (AP) - A telescope arms race is taking shape around the
world. Astronomers are drawing up plans for the biggest, most powerful
instruments ever constructed, capable of peering far deeper into the universe -
and further back in time - than ever before.
The building boom, which is
expected to play out over the next decade and cost billions of dollars, is being
driven by technological advances that afford unprecedented clarity and
magnification. Some scientists say it will be much like switching from regular
TV to high-definition.
In fact, the super-sized telescopes will yield even
finer pictures than the Hubble Space Telescope, which was put in orbit in 1990
and was long considered superior because its view was freed from the distorting
effects of Earth's atmosphere. But now, land-based telescopes can correct for
such distortion.
Just the names of many of the proposed observatories suggest
an arms race: the Giant Magellan Telescope, the Thirty Meter Telescope and the
European Extremely Large Telescope, which was downsized from the OverWhelmingly
Large Telescope. Add to those three big ground observatories a new super eye in
the sky, NASA's James Webb Space Telescope, scheduled for launch in
2013.
With these proposed giant telescopes, astronomers hope to get the first
pictures of planets outside our solar system, watch stars and planets being
born, and catch a glimpse of what was happening near the birth of the
universe.
``We know almost nothing about the universe in its early stages,''
said Carnegie Observatories director Wendy Freedman, who chairs the board that
is building the Giant Magellan Telescope. ``The GMT is going to see in action
the first stars, the first galaxies, the first supernovae, the first black holes
to form.''
When scientists look at a faraway celestial object, they are
seeing it as it existed millions and millions of years ago, because it takes so
long for light from the object to reach Earth.
Current telescopes are able to
look back only about 1 billion years in time. But the new telescopes will be so
powerful that they should be able to gaze back to a couple of hundred million
years after the Big Bang, which scientists believe happened 13.7 billion years
ago. That's where all the action is.
``We hope to answer these questions: Are
we alone in the universe? What is the nature of dark matter and dark energy in
the universe?'' said astronomer Henri Boffin, outreach scientist for the
European Southern Observatory.
Two new technologies enable this extraordinary
quest - one reliant on modern lasers and computing power and the other inspired
by ancient Greek and Roman tilework.
The first is adaptive optics. It allows
telescopes on the ground to get rid of the distortion caused when looking
through Earth's thick atmosphere into space.
Adaptive optics relies on a
laser to create an artificial star, or a constellation of fake stars, in the
sky. Astronomers then examine the fake stars and use computers to calculate how
much atmospheric distortion there is at any given time. Then they adjust the
mirrors to compensate like a pair of eyeglasses. This adjustment happens
automatically hundreds of times per second.
Adaptive optics worked first for
smaller telescopes. But getting it to work for big observatories was a problem.
The first successful use in large telescopes was in 2003 at the twin-telescope
Keck Observatory in Hawaii, an effort that took nine years.
The second
breakthrough involves technology that makes bigger mirrors possible. Instead of
casting a giant mirror in one piece, which is difficult and limits size,
astronomers now make smaller mirror segments and piece them together.
Keck
scientist Jerry Nelson, now working on the Thirty Meter Telescope, pioneered
this technique and said he got the idea from looking at how the Greeks and
Romans tiled their baths. This technique is going from 36 segments in current
telescopes to 492 segments with his new project.
In astronomy, the bigger the
mirror, the greater the amount of light that can be grabbed from the universe.
For the past decade and a half, the Keck has had the largest Earth-bound
telescopes, with mirrors nearly 33 feet in diameter.
However, three giant
land observatories, proposed for construction within the decade, are going to
dwarf those:
The Giant Magellan Telescope. A partnership of six U.S.
universities, an Australian college, the Smithsonian Astrophysical Observatory
and the Carnegie Institution of Washington will place the telescope in Las
Campanas, Chile, around 2016. The plan is for an 80-foot mirror. The cost is
around $500 million.
The Thirty Meter Telescope. The California Institute of
Technology, the University of California and the Association of Canadian
Universities for Research in Astronomy are aiming for a telescope with about a
98-foot mirror by 2018. No site has been chosen. The cost is about $780
million.
The European Extremely Large Telescope. A partnership of European
countries called the European Southern Observatory already has telescopes in
Chile and is aiming for a new one with a mirror of 138 feet, scaled back from
initial plans of 328 feet. The Europeans are aiming for a 2018 completion, but
have not chosen a specific location yet. The cost would be $1.17 billion.
The
managers of these projects are fairly confident they will get the money they
need to complete their grand visions. However, some astronomers worry that there
may not be enough private or government money for all of them, so they find
themselves competing for funding, even as they cheer each other on.
If
completed, ESO's European Extremely Large Telescope would be the biggest of the
new observatories and should be able to see 20 to 100 times more sharply than
the current best land-based telescopes. The Hubble, which set the standard for
stunning astronomical pictures, will seem less amazing.
``Oh, you ain't seen
nothing yet,'' said 2006 Nobel Prize-winning physicist John Mather, senior
project scientist for NASA's James Webb Space Telescope.
The $4.5 billion
Webb Telescope, designed to travel 900,000 miles beyond Earth's orbit, is not
faced with the atmospheric distortion of ground telescopes. Still, it will use
its own version of adaptive optics. Because of temperature fluctuations in the
cold of space, the telescope will have to adjust the shape of its mirrors
automatically. Webb's mirror, which is 2 1/2 times bigger than Hubble's, has 18
segments.
While places like Arizona and Hawaii have been successful sites for
high-quality space images, Chile is the focal point of the next-generation
building boom.
Both the Thirty Meter and European telescope are looking at
several sites there although the Thirty Meter team is also considering Baja
Mexico and Hawaii. What's needed is the right combination of atmospheric
conditions, weather, high altitude, prevailing winds and dark skies.
But
there is more in the works than just the super-sized scopes. Smaller, more
specialized telescopes are in various stages of design and construction.
The
$400 million Large Synoptic Survey Telescope to be built in Chile by 2014 would
survey the sky, constantly shooting a movie of 20 billion objects in the cosmos
and spotting targets for bigger telescopes.
A planned project in Hawaii would
be on the lookout for ``killer asteroids.'' And in Chile, dozens of
high-precision antennas are being erected for a huge radio astronomy
observatory, called ALMA, that would look into the universe in a different
way.
It is the biggest observatories in the works, however, that will provide
the dramatic change in astronomical pictures. The pictures to come, Nelson said
of the Thirty Meter project, will ``knock your socks off, faint stuff that
Hubble can't see.''
On the Net:
Thirty Meter Telescope:
http://www.tmt.org
Giant Magellan Telescope: http://www.gmto.org
European
Extremely Large
Telescope:
http://www.eso.org/public/astronomy/projects/e-elt.html
James
Webb Space Telescope: http://www.jwst.nasa.gov
02/04/08 18:41
EST
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