Rob paused and looked at Regulo, who seemed not in the least disconcerted by the prospect of a collapsing beanstalk. He was staring up at the ceiling now, and thoughtfully tapping his pile of papers. “Are you proposing that as an engineering problem, Merlin?”
“No.” Rob leaned forward. “We both know there’s no good engineering solution to sabotage. But I still think that this is the issue that decides whether or not we can ever build your beanstalk. We have to convince other people that the risks are worth taking. How do we sell them on the idea that the benefits outweigh the risks?”
There was a smile of pure pleasure on Regulo’s face. Rob’s words seemed to delight him.
“You’re the right man for this job,” he said. “You’ve got your finger on the real problem. The engineering is the fun, eh, but the real problem is going to be the permits? Is that what you’re telling me?”
“Of course. It’s the same with every big engineering project. Somehow we have to persuade them back on Earth that they should let us go ahead, even with a small risk of sabotage.”
Regulo had leaned over the desk and rubbed his hand at one part of it. “If I didn’t have an answer to that one, I’d never have called you in the first place. See that sign?”
He tapped the glowing desk top with a thin finger, where the familiar sign ROCKETS ARE WRONG gleamed red on the surface.
“That’s a true statement for four or five different reasons. You just have to pick the argument that serves your purpose at the time. I talked over the risks of this with the environmental control people back on Earth. I told them that we have a basic choice to make. We can go on with chemical and radioactive pollution, year after year, from the rockets that we are using now. That’s not a risk of damage to Earth and the environment, it’s an absolute stone certainty. And they know they don’t have the clout to stop it. Or we can switch to a system that’s completely non-polluting, with a tiny and controllable chance of having an accident.”
Regulo chuckled and shook his head. “They weren’t sure, but you know that the safest thing for a bureaucrat to do is to say no to everything. If I’d left it there, they’d have vetoed us. So I told them that the chance of an accident went up or down, depending on the level of the monitoring operations. They would need to create a new security department, one with a high level of funding. New jobs, new facilities, new equipment. Naturally, the money for that would come from the builders of the beanstalk — us. And naturally, the funds would go to them. Did you ever see a bureaucrat when he sees a chance for a little empire-building? Anyway, here’s your permit.”
He pulled a document from the pile in front of him.
Rob stared at it in amazement. “A permit to build a beanstalk?”
“To build three of them, if we choose to. If you’re going to ask at all, why not ask for a lot? I suggest we think of the first one as having a Quito tether point. That’s where I have the best franchises.”
Regulo suddenly stared sideways at the TV cameras pointed toward the desk. He seemed satisfied with what he saw, and turned his attention again to Rob. “Now then, I’ve given you help on that one. What about your solutions for the others? How do you propose to build it?”
“Let’s start with where.” Rob glanced briefly at his notes, then tucked them away into his pocket. “We have to perform the construction well away from Earth, and we ought to choose a stable point that’s not too far away. I’m proposing that we go to L-4, where we have an existing labor pool to draw on if we need it. There’s a decent-sized solar power satellite there, too, and we’ll need the SPS to run the Spider — unless you have other ideas?”
Now he looked at Regulo, deliberately waiting a moment before he went on, “All right, so we extrude the whole thing up there at one go: load-bearing cable, synchronous drive motors all the way along it to move the cars up and down, and superconducting cables to feed power into those.”
“The Spider can do all that?” Regulo showed surprise for the first time since the conversation had begun.
“That, and more.” Rob felt easier. Up to this point of the meeting Regulo seemed to have thought of and improved on everything that Rob could suggest. Now at last there was something Rob could do that the other man couldn’t.
“Maybe Corrie already mentioned to you that the Spider has a biological component,” he went on. “It’s a lot more adaptable than any ordinary piece of hardware, so changing the fabrication plan as the materials are extruded is no big trick. Originally, I wanted it flexible to handle things like tapering supports for bridges without my needing to re-program. Now it turns out the versatility will come in useful here.”
“Aye, Cornelia did mention the bio thing.” Regulo rubbed at his face with a thin, veiny hand. “Did she tell you just how much we fooled with that damned design, and never once sniffed at a bio-combine system? Maybe it’s time I went back for a technology refresher course.”
“You seem to do pretty well.” Again, Rob couldn’t tell if Regulo was being serious. His facial abnormalities distorted every expression. “So far, I haven’t managed to come up with anything better than your designs. But let me keep going. We get to the point where we have a hundred thousand kilometers of load cable, with power cables and drive attached to it, up near L-4. We need one more thing apart from a powersat, and that’s a ballast weight. It has to be a big one. It provides the tension in the load cable and balances the tether. We can’t attach the ballast until we make contact with the tether, so the ballast weight will be flying around the Earth in its own orbit.
“We fly the beanstalk in, and curve it down to make contact with the tether point — at Quito, if we decide that’s the best place for it. We’ll have to curl in to atmospheric entry along a spiral approach from L-4. The ballast weight swings up and contacts the end of the cable at the same time as the tether end comes in to ground contact — and we’d better not miss that tether, or the whole thing will be off like a slingshot, past the Moon and on its way to God-knows-where. I’ve checked the timing, and I don’t think we have any real problems. The inertia of the system works both ways — you have time to do things. But changing direction or speed is almost impossible unless you have a lot of time to work with.”
“We won’t miss the catch. I’ll be down there to hold and tether it myself if I have to, and damn what the doctors say.”
Regulo’s face was full of resolve. Rob wondered suddenly just what the doctors did say. If anything, the old man looked worse than at their first meeting. How much of Regulo’s body was covered with the terrible deformity that marred his face?
“All right, my lad, what are your other worries?” Regulo broke into Rob’s train of thought. “I agree with you, the fly-in from L-4 or L-5 will get around most of the problems of stability. I’ll always take a situation with dynamic stability over one with static stability, any time. What are you suggesting for the transport system itself? How many cars, how big, how fast?”
“I’m designing for six hundred; three hundred going up and three hundred coming down. There will be a continuous drive arrangement from a set of linear synchronous motors running up and down the entire length of the beanstalk. I’ve chosen a nominal load for each car of four hundred tons.” Rob pulled out his notes and glanced at them again for a moment. “You might want to think about this, see if you agree with me. If you do, it provides us a carrying capacity of about two hundred and forty thousand tons a day. It sounds a lot, but it’s completely negligible compared with the mass of the beanstalk itself. Long term, we’ll have to keep the upward and downward movements pretty well balanced or that will affect the stability, but we have nothing to worry about on a day-to-day basis. As you’ll see from my numbers, with even spacing of the cars we’ll have a velocity of about three hundred kilometers an hour. That’s respectable for travel up through the atmosphere, and not high enough to cause aerodynamic problems.”