Spacecraft hits its comet target
Monday, July 4, 2005 (PARIS)
The Associated Press
MONDAY, JULY 4, 2005
PASADENA, California A space probe hit its comet target early Monday in a
NASA-directed, Hollywood-style mission that scientists hope will reveal clues
to how the solar system formed.
It marked the first time a spacecraft had touched the surface of a comet,
and ignited a dazzling fireworks display in space.
The successful strike 83 million miles (134 million kilometers) away from
Earth occurred just before 0600 GMT, according to mission control at NASA's Jet
Propulsion Laboratory in Pasadena, which is managing the US$333 million (?275
million) mission.
Scientists at mission control erupted in applause and hugged each other
as news of the impact spread.
It was a milestone for the U.S. space agency, which hopes the experiment
will answer basic questions about the origins of the solar system.
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.
An image by the mothership showed a bright spot in the lower section of
the comet where the collision occurred that 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.
''We hit it just exactly where we wanted to,'' co-investigator Don
Yeomans said.
More than 10,000 people packed Hawaii's Waikiki Beach to see the impact
on a giant movie screen.
''It's almost like one of those science fiction movies,'' said Steve Lin,
a Honolulu physician as his 7-year old son, Robi, zipped around his beach
blanket.
Scientists had compared the suicide journey to standing in the middle of
the road and being hit by a semi-truck roaring at 23,000 mph (37,000 kph). They
expect the crater will be anywhere from the size of a large house to a football
stadium and between two and 14 stories deep.
A day earlier, the Deep Impact spacecraft successfully released its
barrel-sized ''impactor'' probe on a high-speed collision course with Tempel 1
- a pickle-shaped comet half the size of Manhattan.
After its release, the battery-powered probe tumbled in free flight
toward the comet and flew on its own without human help during the critical two
hours before the crash, firing its thrusters to get the perfect aim of the
comet nucleus.
A direct hit was a challenge because NASA's Jet Propulsion Laboratory no
longer controlled the probe once it was released from the spacecraft. Even so,
the odds favored success based on previous testing.
Along the way, as the comet closed in, the copper probe took close-up
pictures of the icy celestial body at a rapid clip until its destruction. The
carefully orchestrated crash gave off energy equivalent to exploding nearly 5
tons of dynamite.
The mothership had a front-row seat to the comet strike 5,000 miles
(8,000 kilometers) away. NASA's fleet of space telescopes, including the Hubble
Space Telescope, Chandra X-ray Observatory and Spitzer Space Telescope, and
dozens of ground observatories also viewed the impact.
Soon after the probe's 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 planned to fly within 310 miles (500 kilometers)
of the comet before it activates 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.
As comets circle the sun, their surfaces heat up and change so that only
their frozen interiors possess original space material. Scientists hope to
analyze images of these primordial ingredients jarred loose by the impact to
give new insight into how the sun and planets formed.
Deep Impact launched Jan. 12 from Cape Canaveral, Florida, on a
six-month, 268 million-mile (430 million-kilometer) voyage toward Tempel 1. In
what scientists say is a coincidence, the spacecraft shares the same name as
the 1998 movie about a comet hurtling toward Earth.
No other space mission has flown this close to a comet. In 2004, NASA's
Stardust craft flew within 147 miles (237 kilometers) of Comet Wild 2 en route
back to Earth carrying interstellar dust samples.
The 1,300-pound (590-kilogram) spacecraft snapped its first photo of
Tempel 1 from 40 million miles (64 million kilometers) away in April, revealing
what amounts to a dirty snowball. Last month, still 20 million miles (32
million kilometers) away, scientists saw the comet's solid core for the first
time.
[Non-text portions of this message have been removed]
Post message: [EMAIL PROTECTED]
Subscribe : [EMAIL PROTECTED]
Unsubscribe : [EMAIL PROTECTED]
List owner : [EMAIL PROTECTED]
Homepage : http://proletar.8m.com/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/proletar/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
