Betting on Deep Impact's... Impact On the 4th of July, NASA successfully arranged for a probe to get in the way of a comet. The collision produced a huge cloud of debris and reams of data for scientists to study. They now know more about the makeup of comets. But one office pool among the scientists remains unresolved: What did the resulting crater look like?
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Betting on Deep Impact's... Impact

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Betting on Deep Impact's... Impact

Betting on Deep Impact's... Impact

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ROBERT SIEGEL, host:

The headlines read `Smashing Success,' and it was. On the Fourth of July, NASA successfully steered a copper probe into the path of a comet. The collision packed a punch equivalent of five tons of TNT, and it gave researchers their first look at the material beneath a comet's surface. The team is busily preparing their first results for public release, but there is one thing the mission did not get. As NPR's David Kestenbaum reports, that missing piece has left a $300 office pool in limbo.

DAVID KESTENBAUM reporting:

Before the collision took place, NASA created a fancy animation showing what might happen. Most of it is dead on. A spacecraft called Deep Impact jettisons a heavy probe in the path of a fast-approaching comet that looks like a giant potato. The comet hits the probe. You see a blast of debris and then a beautiful crater. All that did happen, except that the spacecraft never got a picture of the crater. Lucy McFadden is one of the team's leaders.

Ms. LUCY McFADDEN (University of Maryland): That never occurred to us; that we'd blow up so much dust and that it would take so long to clear. We just zipped by, and we just couldn't wait around for the dust to clear.

KESTENBAUM: McFadden's office at the University of Maryland looks like the result of some cosmic collision. The researchers are learning most of the things they wanted to: what the comet is made of, how it's put together. They're studying roughly 4,000 pictures and databases, including beautiful images of the explosion. And in some ways it's interesting that the collision threw up so much dust, to a point.

Ms. McFADDEN: Interesting, yeah, but not for the people who were planning on studying the physics of the crater-formation process by watching the crater grow. We didn't want just one image. We were expecting to see a series of images where we could see it expand--or hoping for that. I mean, it's the way the experiment went, but I'm sure--I know many of my colleagues wished that damned dust would go away.

KESTENBAUM: `Hey,' says a guy who's standing nearby flipping through a magazine, `some of us like dust.' This is Carey Lisse, another scientist on the mission. He bet $20 on what the collision would do and what the crater would look like; so did a number of his colleagues. They were asked to pick from 11 different scenarios. Here's the one he chose.

Mr. CAREY LISSE (Researcher): Impactor hits the comet, maybe makes a little bit of a flash but not much, burrows down and explodes underneath the surface, and we made a 200- or 300-meter-wide crater, OK.

KESTENBAUM: So do you know whether you were right or wrong?

Mr. LISSE: No. Can't tell.

KESTENBAUM: The powder that the collision kicked up surprised some researchers, who thought the comet would be more dense or sticky. Lisse says they now know that this part of this comet had the consistency of meringue.

Mr. LISSE: Think the meringue in a lemon meringue pie, not the pie crust but the meringue. It's about as weak as that. Now at the same time you've got a body that's the size of Washington, DC, and it seems to have structure on it. It's got cliffs and scars we think that may be about a hundred feet tall, so this is an interesting thing. If you were to step on this, you probably could crunching through it pretty easy. It's a very different state of matter than we're used to thinking.

KESTENBAUM: The crater's there. No one knows what it looks like, and the money waits in a bank account.

All right. So who's the guy that's got your money?

Mr. LISSE: Mike Belton. We were teasing him mercilessly. Be nice to him.

KESTENBAUM: We reached Mike Belton at his home in Arizona. He says the idea of the pool was to get researchers thinking about what they expected the collision to do.

Mr. MIKE BELTON (Researcher): I lost personally because I thought there would be a rather strong layer on the surface of the comet that would basically break up into big blocks, and those blocks--we'd see those flying off. That didn't happen.

KESTENBAUM: Many of the scenarios for what would happen in the collision were based on the work of Peter Schultz, a planetary geologist at Brown University. Schultz used a giant gun to make small craters in different materials. Schultz won't say how he bet, but he says the team can study the crater indirectly, looking at debris that came out. The team has also reanalyzed pictures and can make out a hazy, ringlike thing that may be the crater.

Mr. PETER SCHULTZ (Planetary Geologist, Brown University): I think we will find out how big the crater is. We may not find all the gory detail or the beautiful structure that we had hoped to see, but I think we will see the scale of the crater.

KESTENBAUM: He says it might be fun to send the spacecraft on a second rendezvous to get a clean look. Schultz and his colleagues aren't the only ones who want to see the crater up close. Before the mission, the Planetary Society, a space enthusiast group, set up a contest to guess the crater's size. Some 5,000 people entered from dozens of countries. The society has been getting e-mails from some, waiting impatiently for an answer. David Kestenbaum, NPR News.

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