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NASA Hails a Direct Hit on Comet
2005-7-8 6:19:12   
Deep Impact lived up to its name early Monday with a spectacular smash into Comet Tempel 1 that produced a brilliantly glowing plume of debris.

(NASA scientists comment on data received after the success of the Deep Impact mission at NASA's Jet Propulsion Laboratory in Pasadena, Calif. In background is image of Tempel 1 comet after it was struck by the Deep Impact probe.)

Deep Impact kicks up bright plume of debris


"It's still performing like a champ," project manager Rick Grammier said Monday at NASA's Jet Propulsion Laboratory in California. The flyby spacecraft still was sending data to Earth, including pictures of the impactor striking the comet.

One shot looked backward at the receding comet after impact, with the plume of debris lit brightly by the sun. "This speaks a thousand words," Grammier said. "It's an absolutely incredible picture."

The excitement was contagious, as Web traffic at NASA's Deep Impact pages exceeded the busiest Mars rover day, he said.

The scientists are only starting to draw conclusions from the strike, which was designed to look at the primordial material in the comet's guts to answer questions about the birth of the solar system.

The extended outburst from the comet's new crater suggests volatile materials were sustaining it, said principal investigator Mike A'Hearn from the University of Maryland.

"If there's a lot of volatiles there, the outgassing could continue to go on for a long time," even weeks, he said.

In addition, given the images of the plume of debris, it's possible the comet has a soft, dusty surface. There still might be a hard crust underneath, said co-investigator Pete Schultz of Brown University.

But they still don't know how big the crater is, so no one has won the pool at JPL. Is it as big as a house?

"I think it's bigger than that," Schultz said.

The science team has seen a dark feature where the crater would be, but they have not finessed the image enough to know if it's the crater or a shadow.

"That's going to take a little more image processing. We think we're going to find the crater," A'Hearn said.

One thing clear from the images was the brilliant point of impact on this dirty iceball, so clear that it resembled an illustration.

"It was very hot," Schultz said. "You get that when you're slamming in at 6 miles per second."

The scientists also obtained a temperature map of the nucleus before impact.

It's hottest where the sun hits it directly. The map can help them understand how quickly the nucleus reacts to the sun's heating.

That information may give clues to Tempel 1's structure, A'Hearn said.

A deliberately overexposed image shows a "surprising number of jets," material shooting out of spots on the nucleus, A'Hearn said. Scientists will work to trace those dusty streams back to points on the comet and understand why they are there.

Similar jets were seen when the Stardust spacecraft buzzed Comet Wild 2 last year. Yet this comet looks quite different from Wild 2 and from Comet Borrelly, which Deep Space 1 visited in 2001. It's not clear why yet.

"I just look forward to a wealth of data that will take me to retirement," A'Hearn said early in the morning, after the first results came in. Impact occurred at 1:52 a.m. EDT.

Officials couldn't avoid the temptation to pun. NASA Solar System Division Director Andy Dantzler called Deep Impact a "smashing success" that was "quite a hit" for NASA.

The flyby craft did well as it whizzed by the nucleus through the heaviest dust of the coma. "It came out the other side without a single system damaged," deputy project manager Keyur Patel said at the Jet Propulsion Laboratory.

Ball Aerospace built the spacecraft, which had a focusing problem with its high-resolution telescope. It was expected to be overcome with special image processing.

Ground-based and space-based telescopes, such as Hubble, got images of the brightening of the comet, too.

"The success exceeded our expectations," said JPL Director Charles Elachi.

Deep Impact launched from Cape Canaveral on Jan. 12.


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