Nightside City

I waited for her to go on, but she didn't. I considered what she'd just said.

"One charge?" I asked.

She nodded.

"You're pla

"That's right," she said, with a big, stupid, self-satisfied smile.

"That's all?" I was having trouble controlling my face.

"What else do you want?" she said, exasperated. "It's simple enough."

I chewed on my tongue for a minute to keep from screaming and calling her an idiot. That was the problem; it was much too simple.

I wasn't ready to say that straight out. Instead I asked, "But isn't that likely to cause a lot of damage?"

She looked puzzled. "Why?"

"Because," I said, "if you stop the entire planet all at once, there's going to be something of a bump, isn't there?"

That was a truly unforgivable understatement, but she was so calm about it all that I couldn't bring myself to say anything more. I thought that, if I did, I'd start shrieking at her.

"Oh, I suppose so," she said. "But not too much. The planet's already moving so slowly that it should be easy to stop."

"Are you sure?" I demanded. It didn't sound right.

"Of course I'm sure!" she insisted.

"The people at the Ipsy all agree with this?" I persisted. "They don't think it's risky?"

She waved that away. "Of course they agree."

"All of them?"

"They aren't all involved. What business is it of yours, anyway?"

I backtracked. "It isn't, it isn't. Sorry. I was just curious." I tried to look i

"Not enough!" she said, suddenly surprisingly vehement. "Not hardly enough! Besides, the charge isn't ready. It's got to be calculated perfectly and set up in just the right places. I really don't want to hurt anything."

I nodded. "So when will it be ready?"

"I don't honestly know," she admitted. "My people at the Institute will let me know. They tell me it should be ready in a few weeks."

I nodded again. I had to get out of there. "Mis' Nakada," I said. "You've been very kind, and I just have one more favor to ask. As soon as you have a definite date, could you let me know? Please? Just call my com and leave a message; it'll get to me."

She smiled and gave me her best condescending-to-peasants look. "Of course," she said. "I'd be glad to."

"Ah… I know how busy you must be," I said. "Could you put that in your tickler file now, while you're thinking of it?"

The look wasn't quite as friendly now. "Of course," she said again. "It's done."

"Thank you," I said.

Then I left. I had to get out of there fast, before I lost control and shot her.

Chapter Twelve

DEPENDING ON WHAT YOU KNOW ABOUT EPIMETHEUS and planetology in general, you may be wondering either why I wanted to shoot her, or, if you're a little more up on the subject, why I didn't shoot her. I'll take the second question first.

I didn't shoot her because I knew that if I did, I would never make it out of the city alive. I probably wouldn't make it out of the house alive. And the idiots at the Ipsy might just be dumb enough to go on without her. I needed a less direct approach.

As for why she deserved to be shot, just think about it for a minute.

Epimetheus is about 9,056 kilometers in diameter, with a density of seven grams per cubic centimeter. A rough calculation on a unit in my head gave me a figure of twenty-six times ten to the twentieth tons for the total mass, but I probably messed that up somewhere. In any case, we're talking about trillions of tons of mass. We're talking about a very thin crust that's rotating at 138 centimeters a day at the city's latitude.

Now, I admit, that's not very fast. If you were in a cab moving that fast, and it hit a stone wall and stopped instantly, you could probably just step out unhurt. The cab would probably be unhurt. But a cab is a solid piece of fibers and ceramics, designed to take a lot of stress and with a mass of maybe half a ton. A planet's a dynamic system, and there's just so much of it.

Let's suppose that they set off a charge designed to exactly counter the momentum of the planet's rotation-exactly the right amount of energy. Where are they setting this charge off?

On the surface, presumably, or just below.

You think it's going to stop the core? Or the mantle, which isn't even completely solid to begin with?

Hell, no; the crust is going to rip itself loose from the mantle and probably come apart completely. The crust is already pretty thin and delicate on Epimetheus, with volcanoes scattered all along a million fault lines; where most planets have maybe a couple of dozen continental plates, Epimetheus, because of its hot interior, has thousands.

If you wanted to stop the planet from rotating, first you'd have to fasten it all together with something a bit stronger than the hot rock and gravity it has naturally. As it is, a big shaped fusion charge is just going to ram one or two plates back against the others and tear a big hole in the crust-if you're lucky.

More likely it would just vaporize a piece of crust. I've never heard that shaped fusion charges are all that reliable to begin with.

And then there's the meltdown factor.

Let's consider that charge again. It's putting out one hell of a lot of energy, very quickly. Theoretically, most of that's going to be kinetic energy, directed against the planetary rotation. Some of it is going to be light and heat, though; a lot of heat.

And that kinetic energy is bumping right up against the kinetic energy the planet's already got. When you run those together, they don't cancel out; there's this little detail called the law of conservation of energy, which I know doesn't always apply, but it's still a good rule of thumb when you're working with large-scale, low-energy, normal-space systems like planetary surfaces. If the two kinetic energies are perfectly matched, the two moving masses do stop, all right, but the energy doesn't disappear. It just changes form. In this particular example, it mostly changes to heat.

So you've just added who knows how much heat energy to Epimetheus, which is already a very young, hot, and radioactive planet, which is why the nightside is habitable.

Epimetheus is Eta Cass A III. Ever hear of Eta Cass A II? They never agreed on a name for it, because the obvious one, Vulcan, was taken. I grew up calling it Cass II.

It's molten. And that's not because of its proximity to the sun, either. It's a runaway fission reactor. While it was still liquid, still forming, enough of the radioactives settled down to the core to reach critical concentration. It wasn't enough to go bang, but the chain reactions are still going strong, and that whole planet's going to stay molten for a long, long time yet. Not to mention all those unhealthy fission products-though I suppose most of them never reach the surface.

You add enough heat to Epimetheus, and it might melt down, too. Hell, the planet's laced with uranium and thorium and other radioactives-that's why they mine it. A little added heat and motion would stir those radioactives up; because they're heavy, they're already settling down through the mantle toward the core and collecting there. Add heat, and you'll speed that up, at the very least. You'll be adding energy to an unstable system, and you might just be accumulating critical mass in the core, and the whole damn thing could wind up as radioactive slag.

Now, I don't know that Nakada's one big charge would do that, would trigger a meltdown, but I sure as hell didn't want to find out by experiment. Quakes and volcanoes were the least we could expect.