“Three million kilometers, at perihelion.”
“From the center of the Sun, or from the surface?”
“From the center.”
“Hell. We’d only be two and a quarter million from the solar surface. That’s close, too close.”
“But we won’t be there for long,” Nita Lubin broke in. She came forward and stood by the screen. “I think we should do it. We’ve talked about it before, and we always find a reason not to. Let’s try it. We don’t have to stay with the rock, you know. We can separate ourselves on board the Alberich once we get in as far as Mercury, fly on an orbit with a bigger perihelion distance, and re-connect with the rock later.”
“But then we’ll be too late to meet it,” protested Galley. “If we fly past further out, we’ll take longer.”
“Not if we take the Alberich on a powered fly-by. Alexis, you’re just making up reasons to avoid trying.” Nita Lubin seemed to have made up her mind. She turned to their junior crew member. “How long will it take you to work out a decent power trajectory for the Alberich? We’ll need to have a few choices.”
Regulo did not speak. He reached into his pocket, produced an output sheet and held it out to her.
“What’s this?” Nita Lubin glanced quickly over the sheet, grinned, and placed it in front of Galley. “Orbits for the Alberich. He’s really hungry, isn’t he? Well, there’s nothing wrong with that — it’s what we’re all here for. What do you think, Alexis? We’d have a twelve-million-kilometer perihelion for the ship. That’s not too bad, though I suppose I’d better check it for myself. You two might as well get to work putting the drives out on the rock. We should have plenty of time for that if we can really pick up four weeks on the transfer, the way this analysis shows.”
Alexis Galley stood up slowly from the console and looked for a long moment at the other two. “I still don’t like it, but I’ll go along with it. You put up most of the money, Nita, and it’s only right that we try and protect your investment. Remember one thing, though. Neither of you has ever done any work close in to the Sun. I have. We’re going to find that timing is tighter there — you don’t have as much margin for error as we have out here. If you don’t mind, Nita, I’ll check those calculations when you’ve done with them.”
He left the cabin and went forward towards the drive supplies and installation facility. Nita Lubin looked after him thoughtfully. “You know, he’s only going along with this for me, Darius. I’m wondering if we ought to go through with it. Alexis has more experience than the two of us put together.”
Regulo stared at her, his head cocked to one side. “What do you mean, Nita? I thought it was all settled. Look, I don’t know about you but I certainly don’t want to lose to the Pincus group. That’s what will happen if we settle for the usual elliptic orbit transfer. We’ll lose, there’s no question of it.”
His face had gone pale, and his eyes blazed. Nita Lubin looked at him shrewdly. “You are hungry, Darius — more than I ever realized. Well, I still say that’s no bad thing. I’m in this for profit myself, and so is Alexis. You go up front and help him, and let me check your calculations.”
“They’ll be right,” said Regulo. He turned quickly and left the cabin, before Nita Lubin could speak further.
The first stages of the orbit transfer were following the classical pattern that Alexis Galley had pioneered more than twenty years earlier. First the shape of the asteroid was mapped and recorded from multiple angle images. Next came the detailed mass distribution calculated from analysis of seismic data. That determined the place where powerful explosive pellets would be sited in bore holes drilled deep into the rock. Even with these they would gain only an approximate distribution of the internal densities, but that was still their best source of information on the amounts of ammonia, solid carbon dioxide, water and methane ice inside the asteroid — the source of the reaction mass that would power the transfer of the fragment to Earth orbit.
Galley and Regulo were at the computer, working together on the computation of the drive placings. As volatiles were consumed and expelled in flight, the center of mass and moments of inertia of the remaining rock would change. The drive thrust had to remain exactly through the changing center of mass, or the whole planetoid would begin to rotate under the applied torque.
“See now why I’m against your damned hyperbolic fly-by?” grumbled Galley. “When you send anything that close to the Sun, the boil-off rate goes crazy. You lose a good fraction of your volatiles in just a few hours if you go in near enough. That’s going to ruin the center-of-mass calculation. We never run into that sort of problem with an elliptic transfer, but now we have to think about it.”
“We can allow for it,” said Regulo. His voice was confident. “It’s just a matter of a little more calculation. I’ll work out the solar flux as a function of our time in orbit, and that will give us all the boil-off information that we need.”
“Oh, I’m not saying we can’t do it.” Alexis Galley shook his head. “Only that it’s a pain, and we’ll lose another day while we’re at it.”
“Look, I’m not asking you to do it. I’ll be quite happy to handle all the computation.”
The older man looked at Regulo calmly. “Now then, Darius, just cool off. I’m not saying you don’t take your share of the work, and more. I’m just saying that I still don’t care for this whole thing. I’ve only flown one hyperbolic in my whole life, and that was in an emergency medical ship with unlimited thrust. We weren’t trying to steer a billion tons of rock along with us, either. This is a tricky business, one you don’t jump into without a decent amount of thought. If you’re going to work on the calculations, I’ll go out on the rock and take another look at the position of the drive placings.”
“I’d like to help on that, too. I’ve never seen it done before, and I want to learn how. Don’t worry about the boil-off calculations,” Regulo added quickly, seeing Galley’s doubtful look. “I’ll work those up as soon as we come back into the ship.”
“All right.” Galley paused for a second, then nodded his head approvingly. “I’ll say this for you, Darius, I’ve never had a junior man as keen to learn every single thing about this business. Come on, let’s get our suits on. Time’s a-running.”
The Alberich was moored on a short cable, a few meters from the asteroid. The difference in the natural orbits of the two bodies was infinitesimal, barely enough to hold the tether taut. The two men drifted slowly across to the rock and Galley began his careful examination of its surface.
“Here’s a good example,” he said after a few moments, his voice loud over the suit phone. “When you first look at this location you think it’s perfect. There’s solid rock to secure a drive to, and you can see the volatiles right on the surface. But take a look at the mass distribution.” Galley flashed part of the computed interior structure of the planetoid onto the suit video. “See that? The volatiles peter out just a few meters below the surface. Now, compare it with that position over to sunward. There’s a real vein of volatiles there, and the mooring is just as good.” Galley peered closely at the cratered surface, lit by the harsh, slanting rays of the distant Sun. “This looks like a fine one. There’s enough reaction mass in that vein to do us some real good.”
Regulo was studying the video display. “I thought you told me that this mass distribution was just an approximation.”
“It is.” Galley gave a brief bark of a laugh. “Sometimes you get a surprise, no matter how much thinking you do ahead of time. But the approximation is still the best information we have, so there’s no sense in ignoring it unless we actually see something on the surface to tell us more. That’s one reason we came out here.” Galley switched in the ship’s circuit. “Nita? Give us that composition read-out, would you?”