- The Washington Times - Saturday, January 1, 2005

CAPE CANAVERAL, Fla. (AP) — The grown-up boys on the NASA team can hardly wait. On the Fourth of July, they get to break up a comet, Hollywood-style.

“Blow things up? I’m there. Yeah, I don’t have any issue with that,” said Richard Grammier, manager of the project for Jet Propulsion Laboratory (JPL).

The spacecraft is called Deep Impact, just like the 1998 movie about a comet headed for Earth. NASA’s goal is to blast a crater into comet Tempel 1 and analyze the ice, dust and other primordial stuff hurled out of the pit.

Mission planners say the energy produced will be like 4 tons of TNT going off — producing a fireworks display for the world’s observatories.

Scientists know little about comets and even less about their nuclei, or cores. They believe that penetrating the interior for observations by space and ground telescopes is the next best thing to actually landing, scooping up samples and delivering them to Earth.

“We’ll understand how the comet is put together, its density, its porosity, whether it has a surface crust and underlying ices, whether it’s layered ice, whether it’s a wimpy comet or whether it’s a rock-hard ice ball,” said Donald Yeomans, a senior research scientist at JPL in California — and an adviser on the movie. “All of these things will become apparent after we smack it.”

Astronomers are counting on Deep Impact to live up to its Hollywood name on July 4, six months after its mid-January launch.

Deep Impact will travel 268 million miles from the time it is launched aboard an unmanned rocket until it intersects with Comet Tempel 1 just beyond the orbit of Mars, at a point more than 80 million miles from Earth.

Liftoff is targeted for Jan. 12, two weeks late because of software and rocket problems. NASA has until Jan. 28 to launch Deep Impact. After that, Tempel 1 will be beyond rocket reach and scientists will have to pick another comet and swallow a lengthy delay.

That is what happened to the European Space Agency’s Rosetta spacecraft, which will attempt a controlled landing on a comet, but not until 2014.

Deep Impact, by contrast, will provide “instant gratification,” Mr. Grammier said. The entire $330 million mission should be wrapped up a month after impact.

Comet Tempel 1 is ideal from a scientific and demolition perspective.

It is a typical comet — all the better for scientific analysis. Yet it has a large nucleus and weak coma, or gaseous cloud surrounding the nucleus — all the easier for the impactor to survive the dusty obstacle course and nail the nucleus.

Mr. Grammier said the latest calculations put the chance of the impactor missing its target at less than 1 percent. The automatic navigation software already has been tested in space.

“We all feel pretty comfortable with that [the odds], but as we’ve all said before, we’re doing something we haven’t done before,” he said.

No matter what, fans of the 1998 disaster film can rest easy.

NASA guarantees that no matter how powerful the punch or how big the crater, Deep Impact will barely alter the comet’s orbital path around the sun and will not put the comet or any part of it on a collision course with Earth.

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