(SNES) Keck and Adaptive Optics

[Albireo54@aol.com]

Hi everyone,

It's not often that a newspaper as noted as The Washington Post carries
prominent stories or commentary dealing with astronomy. But they did
yesterday, probably due in large part to the article's author, noted
columnist and TV commentator George Will (of ABC's Sunday Morning fame).
Shamelessly stolen from their website (which at least I'm crediting @
http://www.washingtonpost.com/wp-dyn/articles/A18547-2002Aug30.html) the full
article on Keck and adaptive optics follows, and I hope you find it
interesting.

washingtonpost.com
Wonderment in the Stars
By George F. Will

Sunday, September 1, 2002; Page B07
ATOP MAUNA KEA, ON HAWAII'S BIG ISLAND -- On a clear day, you can see almost
forever. With the help of adaptive optics, almost back to the beginning of
this universe. And it is usually clear here at 13,796 feet above sea level,
and above half of the atmosphere's oxygen. That is why the W.M. Keck
Observatory's two telescopes, primarily operated by the University of
California and the California Institute of Technology, are here, far from
urban lights and above much of the atmosphere that, although it makes the
stars twinkle prettily, does so by distorting light.
Hence the need for adaptive optics. This technology became available for
civilian science when the end of the Cold War led to the declassification of
some devices developed for the Strategic Defense Initiative (SDI).
The Keck telescopes -- the world's largest -- are gathering light produced
shortly (as these things are reckoned; about 800 million years) after the Big
Bang, just under 14 billion years ago. Analysis of the light, which can be
done by astronomers working anywhere, yields information about the life cycle
of stars. (Grim news: Our star, the sun, is doomed, so we are too, in less
than 2 billion years.) The Keck telescopes have detected more than 60 planets
orbiting other stars. Ten years ago, the only planets we knew of were those
orbiting our own sun.
It is axiomatic that not only is the universe stranger than we know, it is
stranger than we can know. But one reason the Keck telescopes are
significantly augmenting our store of knowledge is the application to
astronomy of adaptive optics developed for SDI. SDI's challenge is to target,
from space, ballistic missiles launched on Earth. This requires making
ultraprecise measurements from space, through the distortions of the Earth's
atmosphere. Astronomy's challenge involves looking outward -- analyzing light
that is distorted by the atmosphere before it reaches telescopes on Earth.
The Keck telescopes each weigh 300 tons, stand eight stories tall and involve
operations of more precision than those of the finest wristwatch. They can
gather 13-billion-year-old light that is 500 million times fainter than the
naked eye can see. They gather the light using a primary mirror 33 feet in
diameter, composed of 36 hexagonal segments, each engineered to conform to
within a millionth of an inch of single continuous surface.
But the really remarkable device is a mirror about the size of a man's hand.
Distortions in the gathered light are removed by bouncing the light off this
mirror, which has 400 pistons operated by tiny, computer-driven motors that
make adjustments in the mirror's surface 642 times a second.
>From 1609, when Galileo built a refracting telescope (a lens assisting the
naked eye), until the Hubble space-based telescope was launched in 1990, the
atmosphere complicated astronomy. However, Hubble, which cost more than all
other telescopes in history combined, does not make Earth-based telescopes
anachronistic.
Hubble and its successors -- next comes the Next Generation Space Telescope
-- operate in the cold vacuum that is space. But a multinational consortium
has proposed an Overwhelmingly Large Telescope that would gather light on
Earth with 2,000 panels of mirrors in an apparatus the size of a football
field. Ever-better land- and space-based telescopes will find tantalizing
hints about how the expansion of the universe (actually, this universe; there
may be many others) began -- a Big Bang? -- and whether it will continue to
expand or will collapse back on itself in a Big Crunch.
In any case, Earth's fate is not going to be pretty, so what's the use in
wondering? Because wondering is what we are for.
Mauna Kea is a dormant volcano. About 40 miles southeast of here, lava from
the Kilauea volcano, boiling with heat left over from Earth's formation 4.35
billion years ago, has recently been spilling across a highway and into the
ocean. To stand a few hundred feet from the stream of lava plunging into the
Pacific, amid the searing heat and sulfurous fumes, is to sense what the Keck
Observatory, in its very different setting, explores -- the violent
impermanence that permeates the entire universe.
"We are curious people," says Keck Observatory director Frederic Chaffee
matter-of-factly. "And the universe is an amazing place." The most amazing
things in it are the curious creatures. They have evolved literally from
stardust, becoming conscious beings capable of building -- indeed, their
glory is that they are, in a sense, incapable of not building -- mountaintop
telescopes, silhouetted against the edge of the atmosphere, searching for
clues as to how all this started and how it will end.
) 2002 The Washington Post Company
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