“You mean, if we take off and… if there’s a computer setting for it,” Ivo said. “Doesn’t it keep track of any changes in our location, and compensate?”
“Naturally. It’s been doing it right along while you practiced. Otherwise every one of the coded locations would be off by the distance we are from the torus. But under actual acceleration there would be drift because of the change in our orientation. Is your hand steady enough to compensate?”
“I can try,” Ivo said.
She strapped him down while he held the focus. “We’ll have to employ intermittent bursts, and change our own orientation erratically,” she said. “That way they won’t ever be quite sure where we’re going.”
“Where are we going?” Groton inquired.
“Neptune,” Ivo said, but it wasn’t funny.
“What’s two billion, eight hundred million miles among friends?” Afra said, and that wasn’t funny either. Ivo was sure it would be years before they could get to such a planet on an economy orbit. The 1977 probe of the four gas giants, after all, was still less than halfway out.
“We may be able to fool them for a little while — a few hours, say — but will it change the end?” Ivo asked her.
“No. Unless we undertake sustained acceleration, the advantage is with them. They have to catch up eventually.”
Ivo still had the focus on the printed warning in the station common room. “Oh-oh,” he said. “Somebody is changing the sign.”
A technician, seeming to move carelessly, picked up the first sheet with a gloved hand and deposited another. Ivo read it off:
ROBOT BEING FITTED. ACCELERATE IMMEDIATELY. URGENT.
“I’ll get on it,” Groton said. “One G until we think of something better.” Ivo heard him scrambling through the lock.
“Why can’t we set course for — well, Neptune, since it’s vacant and far out — and keep clear of them that way? It might take a little time, but at least we’d be safe until we could figure out something better.”
“You’re right,” Afra said sourly. “At a million miles per hour, direct route, we could make it within four months. At a steady one-gravity acceleration we could achieve that velocity in, oh, half a day. We have supplies for the five of us for a good year.”
Weight hit them as Groton cut in the drive. They were on their way — somewhere.
Ivo, still on the scope, lost the focus, but was able to bring it back by diligent corrective twists. The computer was on the job, holding to the coded location, but it didn’t care what way up the picture was, and it was evident that the loaded weight of the ship threw the calculations off a trifle. The computer was not using the macroscope; it was judging by thrust and vector to estimate the changes and corroborating by telescopic observations. Trace corrections were necessary.
“What’s wrong with that idea, then?” he asked, trying not to sound plaintive.
“First, that robot can take more acceleration than we can, since it has no fallible human flesh to hinder it. It would catch us enroute if the regular ship didn’t. Second, we might get a little hungry, if we did get away, after that year.”
“Oh.” That stupid feeling was threatening to become chronic. “Couldn’t we, er, grow some more food? Refine natural resources or sprout whole grain — I saw bags of—”
“On Neptune?”
He didn’t press the point. “We could come back within the year. The situation could change in that time. Politically.”
“I suppose it could, and we could. That leaves only the problem of outrunning the robot ship.”
“Oh.” He kept forgetting that. “Wait a minute! I thought Joseph was a special vehicle. An atomic heat-shield, or something. Brad told me—”
“We are traveling in verbal circles,” she said. “Joseph can probably deliver enough thrust to fire us off, even burdened with the weight of the macroscope housing, at a sustained ten gravities. No problem there. The robot would run out of chemical fuel in a hurry trying to match that.”
“How long would it take to reach Neptune at ten G’s?”
She was silent a moment, and he knew she was working it out with a slide rule. This, at least, was one problem she couldn’t do quickly in her head or answer from memory, and he refrained from reminding her that he could.
“Assuming turnover at mid-point for deceleration, with constant impetus, top velocity of thirteen thousand, two hundred miles per second — ouch! That’s one fourteenth light-speed! — we could make the trip in just five days.”
“Why not?” he asked, satisfied.
“No reason worthy of mention. Of course, we’d all be dead long before we arrived, if that’s any disadvantage.”
“Dead?”
“Did you fancy surviving at a sustained ten G’s?”
Ivo thought about weighing over three quarters of a ton for five days without letup. Power, he decided, was not everything. And of course he should have known that; she had already stated that problem, though it hadn’t sunk in before. He’d been thinking minutes, not days, for that acceleration.
“You have too many nays for my yeas,” he told her. “Suppose we take off at a steady one G in the general direction of Neptune. How long will it take that UN cruiser to catch us?”
“That depends. The manned one is our immediate problem. If it orients immediately and projects for interception, it could rendezvous within two days. If it takes a more conservative approach, to economize on fuel and allow for our possible maneuvering, it would take longer. Since they’ll know fuel is not a problem for us, the latter course is more likely. They wouldn’t want to damage the macroscope. They would try to keep us occupied until the robot was functional, which might be several more days.”
“How would they know about our drive? I thought that was Brad’s private project.”
“Nothing is that private — not from the organization footing the bill. But spectroscopic analysis of our drive emission would remove any doubts they might harbor. That would make them more cautious about closing with us, but it wouldn’t stall them very long. They’d be even more determined to capture us intact, for the sake of that heat-shield.” She paused. “We might bluff them a while, though. We’ll be heading into the sun, and if we threatened to lock suicidally on that—”
“But Neptune is farther out than we are. We’d be headed away from the sun.”
“Not when Neptune’s in conjunction.”
“Conjunction?”
“The opposite side of the sun from Earth.”
“I thought that was opposition.”
“Brother!” she said in exasperation. Then: “Exactly what, if anything, were you thinking of using those two or more days of freedom for?”
He refrained from making a cute answer. “The macroscope.”
“I had the distinct impression you were already occupied in some such capacity. One does live and learn.”
“I meant the programmed aspect”
“Oh.” It was her turn to feel stupid. It set her back only momentarily. “It seems to me that our problem is fairly well defined. We can’t expect to outmaneuver or outrun the UN pair of ships, nor are we in a position to build any fancy equipment to discommode them. Surely you don’t expect to adapt the mind-destroyer impulse as a personal weapon?”
“No. But I’m convinced there is galactic information on that channel, if only we could get past the barrier. No one has ever looked beyond that opening sequence.” Was there anything beyond, he wondered abruptly, or did it merely repeat endlessly?