By ALICIA CHANG, AP Science Writer
It sounded like science fiction -- NASA scientists used a space probe
to chase down a speeding comet 83 million miles away and slammed it
into the frozen ball of dirty ice and debris in a mission to learn how
the solar system was formed.
The unmanned probe of the Deep Impact mission collided with Tempel 1,
a pickle-shaped comet half the size of Manhattan, late Sunday as
thousands of people across the country fixed their eyes to the
southwestern sky for a glimpse.
The impact at 10:52 p.m. PDT was cause for celebration not only to
scientists at NASA's Jet Propulsion Laboratory in Pasadena, but also
for the more than 10,000 people camped out at Hawaii's Waikiki Beach
to watch it on a giant movie screen.
"It's almost like one of those science fiction movies," said Steve
Lin, a Honolulu physician.
The cosmic smash-up did not significantly alter the comet's orbit
around the sun and NASA said the experiment does not pose any danger
to Earth -- unlike the scary comet headed for Earth in the 1998 movie,
"Deep Impact."
Scientists at mission control erupted in applause and exchanged hugs
as a voice on a speaker proclaimed, "Team, we got a confirmation."
It was a milestone for the U.S. space agency, because no other space
mission has flown this close to a comet. In 2004, NASA's Stardust
craft flew within 147 miles of Comet Wild 2 en route back to Earth
carrying interstellar dust samples.
"A lot of people said we couldn't do this or wouldn't be able to pull
it off," said Rick Grammier, the mission's project manager. "It
happened like clockwork and I think that's something to be proud of on
America's birthday."
Rough images by the mothership that released the probe on its suicide
mission 24 hours earlier showed a bright white flash from the comet
upon impact, which hurled a cloud of debris into space. When the dust
settles, scientists hope to peek inside the comet's frozen core -- a
composite of ice and rock left over from the early solar system.
In Darmstadt, Germany, David Southwood of the European Space Agency
congratulated NASA and controllers erupted into applause upon impact.
"The Deep Impact mission brought the world together in an excellent
opportunity to make a new step into the advancement of cometary
science," he said.
The European agency was observing and photographing the comet collision
with its Rosetta spacecraft, which will attempt to rendezvous with a
comet in 2014.
"I had some doubts, quite frankly, but it was quite spectacular and a
deserved success," said Manfred Warhaut, who heads ESA's Rosetta
mission. "The whole thing was so flawlessly put in place and executed
it deserves some respect."
The camera of the Deep Impact probe temporarily blacked out twice,
probably from being sandblasted by comet debris, NASA scientists
said. Still, the probe -- on battery power and tumbling toward the
comet, using thrusters to get a perfect aim -- took pictures right up
to the final moments, revealing crater-like features. The last image
was taken three seconds before impact.
The energy produced from the impact was equivalent to exploding five
tons of dynamite and it caused the comet to shine six times brighter
than normal.
Scientists had compared the barrel-shaped probe's journey to standing
in the middle of the road and being hit by a semi-truck roaring at
23,000 mph. They expect the crater left behind to be anywhere from the
size of a large house to a football stadium and between two and 14
stories deep.
Soon after the crash on the comet's sunlit side, the mothership
prepared to approach Tempel 1 to peer into the crater site and send
more data back to Earth. The spacecraft was to fly within 310 miles of
the comet before activating its dust shields to protect itself from a
blizzard of debris.
Comets are frozen balls of dirty ice, rock and dust that orbit the
sun. A giant cloud of gas and dust collapsed to create the sun and
planets about 4.5 billion years ago and comets formed from the
leftover building blocks of the solar system.
NASA's fleet of space telescopes, including the Hubble Space
Telescope, Chandra X-ray Observatory and Spitzer Space Telescope, and
dozens of ground observatories recorded the impact.
Deep Impact launched Jan. 12 from Cape Canaveral, Fla., on its 268
million-mile voyage. Scientists say the choice of the mission name was
a coincidence and not inspired by the movie.
On the Net:
Deep Impact mission: http://www.nasa.gov/deepimpact
Copyright 2005 The Associated Press.
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Lisa Minter (lisa_minter2001@yahoo.com)