- ASPEN - Researchers are more
sure than ever that extraterrestrials exist - whether they are microbes
eking out a living on an icy planet or intelligent beings inhabiting a
watery blue world 5,000 light-years away.
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- "There must surely be other stars like our sun,
and other planets like the Earth," said University of California at
Berkeley planetary scientist Geoff Marcy during a recent planetary conference
in Aspen. "Primitive life, at least, must be common in the universe."
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- The planet hunters gathered in Aspen to celebrate the
nearly 150 "extrasolar" planets found in the past 10 years, and
to discuss new ways to search the skies.
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- Many of the attendees at last week's conference were
from Colorado, which has become a hub for planetary research. The University
of Colorado, for example, is one of the leading universities in the country
for research, and Ball Aerospace in Boulder built most of the science instruments
used on the Hubble Telescope.
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- The research has proved invaluable.
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- Many of the planets that had been found were "hot
Jupiters" - huge, gassy planets so close to their central stars that
life seems unlikely.
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- But in recent months, astronomers have improved their
instruments to detect smaller worlds. They're finding planets that orbit
far enough from their parent stars to make water - thought to be necessary
for life - possible.
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- Within a few decades, the researchers say, they may be
able to detect the chemical signature of life in the atmosphere of an Earthlike
planet
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- Science-fiction writers predicted it decades ago, and
now scientists are realizing it's probably true, said Bruce Jakosky, a
planetary scientist at CU.
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- "We're recognizing that life on Earth does not appear
to be anything special," he said.
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- Here, life took root as soon as it could, almost immediately
after meteorites stopped their fiery bombardment of the young planet, Jakosky
said.
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- The main message from a decade of planet discoveries
is that solar systems dot the Milky Way, circling at least 3 percent of
stars. About 200 billion stars are in the galaxy.
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- Researchers could never have predicted the discoveries
of the past decade.
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- In early 1995, two teams reported dismal failures in
planetary searches. Many scientists began to conclude that our own solar
system was alone, a lucky quirk, said Michel Mayor of Switzerland's Geneva
Observatory.
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- But then, his team calculated that the faint wobble of
a sunlike star had to come from a giant planet spinning quickly around
it.
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- Marcy's group confirmed it: The gravitational tug was
from a planet half the mass of Jupiter, orbiting its star about every four
days.
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- The techniques used to detect such wobbles have been
honed since then. Researchers are experimenting with other telescopic techniques.
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- But the next big leap in planet detection - the discovery
of other Earthlike planets - probably won't happen until at least 2007,
scientists say, when NASA plans to launch the Kepler space telescope.
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- Engineers with Ball are building that instrument now,
said Ball's Harold Reitsema.
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- "We're encouraged by all of these discoveries ...
to believe that many stars have planets," Reitsema said.
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- NASA and the European Space Agency are also beginning
to plan other missions, to launch sometime after Kepler: the Space Interferometry
Mission, the Terrestrial Planet Finder and Darwin.
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- But what will happen next isn't clear, although one thing
is: There won't be any manned visits to these planets anytime soon, as
they probably are tens or thousands of light-years away.
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- Berkley's Marcy ran through a series of calculations
suggesting there could easily be thousands of advanced civilizations in
the Milky Way.
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- "There's only one problem: Where are they? Why haven't
we seen them?" Marcy said.
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- Researchers have found no writing on the moon, no crashed
spaceships on Mars, no messages floating through space.
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- Maybe civilizations just don't last long enough to communicate
with one another, he suggested. And perhaps Darwinian evolution, generally
believed to be an inevitable consequence of life, doesn't inevitably produce
intelligence.
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- "Maybe there are other ways to survive and be the
fittest," Marcy said.
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