She stared at him. "We couldn't get out of there in under a half hour. We could skip the maintenance, but we'd still have to refuel."

"I know. Saber, I don't want to leave anyone on the ground."

"Hell. Nobody does. But all that would happen if we went back is that we'd get caught down there with them."

"Not necessarily." He picked up their passenger manifest, and looked over the names. There were three private vendors on board and three dependents. He also had two geologists, a hydroponics expert, and an astrophysicist. Total of ten. (The hydroponics expert was heavy, the kids were light. They'd been able to put an extra child on board.)

The astrophysicist should be just what he needed. He asked Saber to go below and invite her onto the flight deck.

Janet Koestler was middle-aged, slightly overweight, with a plump, apple-pie expression. It was easier to imagine her surrounded by grandkids than working with telescopes. "How can I help you, Captain?" she asked after he'd seated her in Saber's chair.

"Professional question?"

"Sure."

"I wonder if you could describe for us precisely what'll happen when Tomiko gets here? When it hits the Moon?"

Ahead, the Earth was rising.

"In what way?" she asked.

"Is the Moon going to explode?"

Her brow furrowed. "No," she said. "The Moon can't explode. It's really a fairly cohesive body."

"Then what's going to happen?"

"I haven't seen the calculations, but this comet is very big. It's an anomaly. And it's coming at a velocity I'd have thought impossible.

"A comet this size, if it were hitting Earth, would carve out a crater roughly thirty-six hundred kilometers in diameter. That's more than the diameter of the Moon." She paused for effect. "That tells me the Moon will be broken apart." She looked down at the lunar surface. "Everything in the immediate neighborhood of the impact will be vaporized, probably well toward the core.

"The comet's going to melt a lot of rock. A lot. Some of it will be blasted clear of the surface. Or maybe a more correct way to put it is, ejected from the gravitational center. Some will even be blown clear of the Earth-Moon system and go into solar orbit."

"But the Moon, or most of it, will still be here? Is that what you're saying? Because that's not what we've been hearing."

She frowned. "It's just very hard to predict this event. Look, the comet will fracture the Moon. There's no question about that. It'll convert it into a cluster of loose rock. Everything that can be broken will be broken. The shock will cause the rock to drift apart. It'll spread out around the Moon's orbit, and some of it will probably form a kind of shell around the Earth, at about the lunar radius. I'd want to do some work on this, but I imagine, given enough time, the particles will reform. And there'll be another Moon. Smaller, I would think." She took a deep breath. "There's another interesting possibility."

"Which is?"

"The Earth will acquire a set of rings. Over the long term."

Saber asked how long was the long term.

"Several million years. Certainly nothing we need concern ourselves with."

Tony leaned toward her, attentive. "Doc," he said, "I'd like to ask a hypothetical question. You've had a chance to look at the Micro?"

"I beg your pardon?"

"This vehicle. The one we're in."

"Well, yes. I've seen it, more or less. I'm in it."

"If it were a few thousand feet over Moonbase at the time of collision, what would you think about its chances of survival?"

"Not good."

"Can you be more specific?"

She shrugged. "Well, if the bus were directly over Moonbase, it would have one thing going for it. Impact will take place on the far side. But there's going to be a very large fireball. My guess is that the fireball will come right over the pole and engulf the entire northern hemisphere."

"Moonbase is at Alphonsus," Tony reminded her. "Thirteen degrees south."

"Maybe I should have said it will engulf the entire Moon."

"How high would I have to be to be safe?"

"Preferably halfway to Earth. At least. Captain, none of this is my field of expertise. I really don't know." She looked at him, and the smile, which had seemed a permanent part of her features, faded. "You're not planning on doing anything like this, are you?" Moonbase, Director's Office. 11:03 P.M.

Chaplain Pinnacle hadn't been the first volunteer. A mechanic named Tamayaka had offered to stay in exchange for payment of future college expenses for his three kids; and a young optics expert, distraught over the philandering of her new husband, had asked to remain. Chandler had accepted neither. He was disappointed at the reaction of his senior people. Only Jill Benning had openly opposed him. But the others had stood by and left him to defend the only reasonable position as best he could. Eckerd was behaving as if he was doing Chandler a favor. Hawkworth walked around looking like a martyr.

Eckerd, who headed Health and Safety, knew about the director's heart problems. Chandler wondered whether he had pursued his knowledge to its logical conclusion: that it was far less difficult for Chandler to play the hero than it was for the others. And that hard reality chilled him. Still, it did not ease his smoldering anger. With or without the heart problem, he would have done the right thing. He knew that.

After the chaplain called, Chandler simply put out an amended list, inserting the chaplain's name directly above his own. That bumped everybody else, except Evelyn, up one slot. Then had come the shocker: The vice president was staying!

Chandler had his doubts that Haskell wouldn't change his mind. But he'd duly inserted the name, scheduled Benning for a flight, and moved the others up another notch. Benning had told him that he shouldn't think for a minute that this would get him and Hampton and the corporation off the hook. She was going to sue everyone in sight.

He wondered what they'd do if Haskell did change his mind. Call her back and tell her she was going to get to stay after all?

BBC WORLDNET. 11:07 P.M.

Excerpt from an interview with Dr. Olive Ellsworth of the Anglo-Australian-Observatory in New South Wales, conducted by Connie Hasting. Ellsworth: The section we've highlighted is the impact area. It's on the far side, about a hundred miles west of Mare Muscoviense. It'll be coming in at roughly four hundred fifty-five kilometers per second, which is a slight decrease in velocity since we first saw it. That's due to the gravitational influence of the Sun, of course. Hasting: And it's the center of the comet that we have to worry about. Right? Ellsworth: Yes, Connie. It's the center, the nucleus, that will do the damage. Hasting: And the coma is the part that glows? Ellsworth: The coma's a cloud of gas and dust. When a comet gets near the Sun, it begins to heat up, and we get a coma. And a tail. Or, as in this case, sometimes two tails. Hasting: How big is the coma? Ellsworth: This one's about three hundred thousand miles across. Hasting: Three hundred thousand miles? That's pretty big. Ellsworth: Actually, it's smaller than you might expect from an object this large. That might be because of the composition of the comet: There simply may not be that much material to burn off. Or it may be that its passage through the solar system has been so quick, the Sun hasn't had time to work its way. Probably a combination of the two. Hasting: In these pictures it has a pair of tails. Ellsworth: Yes. The ion tail, this one, is about six million miles long. Hasting: But when I look at it in the sky, all I see is a large fuzzy patch. Ellsworth: The tails are running in front of it, so they're not easy to see for an earthbound observer. Hasting: The tails are in front? Ellsworth: Oh, yes. Comets' tails always point away from the Sun. The solar wind causes that. (Displays images.) These were taken from the Venusian probe. Hasting: It is lovely…I wonder if you can tell us what's going to happen tomorrow night? Ellsworth: Let's look at the graphic. You understand, this comet would be less destructive if it were moving at the velocity comets usually move in the solar system, at thirty or forty kilometers per second. But this is going much faster, and consequently it will hit the Moon very hard. You'll observe, it's approaching the Moon now. Hasting: (Nods.) Ellsworth: Here, it breaks through the outer lunar mantle. What's actually happening is that the area where the comet impacts is being vaporized to a depth of several hundred miles. Hasting: It almost looks as if it's splashing in. Ellsworth: Oh, yes. Splash is the right word. That's how craters form, you know. The material melts under the impact. This comet is unlike anything we've seen before. • • • SSTO Rome Flight Deck. 11:10 P.M.