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Space probe crashes into comet

A NASA probe smashes into its comet target, setting off a spectacular fireworks show that scientists hope will reveal clues to how the solar system was formed.
Mission controllers look at images of the Deep Impact probe’s collision with Comet Tempel 1 at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., on Sunday.Robert Lachman / Pool via AP
/ Source: staff and news service reports

A NASA probe smashed into its comet target late Sunday, setting off a spectacular fireworks show that scientists hope will reveal clues to how the solar system was formed.

"What a smashing success!" Andy Dantzler, NASA's solar system division director, said at a post-impact news briefing for the $333 million Deep Impact mission.

Deep Impact’s “Impactor” probe hit Comet Tempel 1 just as scheduled, just before 11 p.m. PT Sunday (2 a.m. ET Monday), marking the first time a spacecraft touched the surface of a comet.

The 820-pound (373-kilogram), copper-sheathed Impactor probe was released by its “Flyby” mothership a day earlier. 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 take perfect aim at one of the brightest spots on the comet nucleus.

Impactor’s imaging system sent back pictures of the potato-shaped comet right down to the last three seconds of its existence, while Flyby watched the impact from a front-row seat 5,000 miles (8,000 kilometers) away. The blast took place 83 million miles (133 million kilometers) from Earth.

Ground controllers at NASA's Jet Propulsion Laboratory in Pasadena jumped and hooted for joy as the first post-impact images flashed on the huge screens at mission control. Flyby’s view showed bright rays of debris streaming from the impact site.

“We hit it just exactly where we wanted to,” said JPL’s Don Yeomans, a member of the Deep Impact science team.

NASA quickly put images from the impact online, generating as much Web traffic as the peaks for NASA's Cassini mission to Saturn and the twin-rover missions to Mars, said JPL Director Charles Elachi. At times, the space agency's Web site slowed to a near-standstill, he said.

More than 10,000 people packed Hawaii’s Waikiki Beach to watch the impact on a giant movie screen. “It’s almost like one of those science fiction movies,” Honolulu physician Steve Lin said as his 7-year-old son, Robi, zipped around his beach blanket.

Sampling the solar system's leftovers
Comets are leftover building blocks of the solar system, which formed when a giant cloud of gas and dust collapsed to create the sun and planets. Because comets were born in the system’s outer fringes, their cores still possess some of the primordial ingredients, and studying them could yield clues to how the solar system formed 4.5 billion years ago.

Impactor’s blast was aimed at kicking up pristine material from the comet’s interior, which could be chemically analyzed by Flyby’s scientific instruments during the encounter.

The Impactor probe shot close-up pictures at a relative speed of 23,000 mph (37,000 kilometers per hour) until it hit the comet, unleashing as much energy as almost 5 tons of dynamite. After that, the 1,325-pound (600-kilogram) Flyby mothership took over recording the scene through its high-resolution telescope. Flyby was to approach within 310 miles (500 kilometers) of the 3.7-mile-wide (6-kilometer-wide) comet.

NASA’s brigade of space-based observatories, including the Hubble Space Telescope, Chandra X-ray Observatory and Spitzer Space Telescope, were pointed toward the scene, as were telescopes on Earth. Observers reported that the comet’s brightness increased by a factor of six, according to the mission’s principal scientific investigator, Michael A’Hearn of the University of Maryland.

Pictures of the collision from Flyby showed a cone-shaped plume of debris spraying into space — just what the scientists were looking for. The resulting crater was expected to range anywhere from the size of a large house to a football stadium and be between two and 14 stories deep. (The Planetary Society had sponsored a guessing game on the crater’s size.)

Six-month journey
Deep Impact blasted off in January from Cape Canaveral, Fla., for its six-month, 268 million-mile (429 million-kilometer) journey.

In what scientists say is a coincidence, the spacecraft shares the same name as the 1998 movie about a comet that hurtles toward Earth. In a case of science imitating fiction, the mission’s findings on comet composition could conceivably help researchers draw up strategies for diverting celestial objects that might threaten Earth.

Discovered in 1867, Tempel 1 moves around the sun in an elliptical orbit between Mars and Jupiter every six or so years. Scientists emphasized that there was no chance that the mission’s Impactor could destroy Comet Tempel 1 or put it into a hazardous orbit.

No other space mission has flown this close to a comet. Last year, NASA’s Stardust craft flew within 147 miles (235 kilometers) of Comet Wild 2 en route back to Earth carrying interstellar dust samples.

Deep Impact 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.

This report includes information from The Associated Press and