“I see,” said Tom, who didn’t see at all. “But don’t you have to have starting coordinates before you can plot an orbit?”
“Of course. You can’t hope to make connection with any point in space unless you know where you’re starting from.”
Tom glanced up at the view screen. They were far beyond the range of the Earth ground-to-air barrage now, and all that was visible was a vast expanse of blackness peppered with stars. “So how can you ever tell where you are?”
The question seemed a little foolish to Ben. “We’re in the cabin of a ship, naturally.”
“But where’s the ship?”
“Relative to what?” Ben said. “Relative to Earth? If that’s what you mean, I don’t know and couldn’t care less. The computer could tell me, of course, if I had to find out. The important thing is where the ship is, relative to where we’re going right now. I had to establish that before I could even start this orbit.
I also had to decide whether I wanted a long, low-energy orbit or a fast, high-energy course. Now I’ve got time to pin down the details and see just how fast we can afford to travel to intersect Mars’s orbit in the shortest possible elapsed time.”
“You mean you can pick your travel time?” Tom asked incredulously.
“Within the ship’s energy limits, yes. We have so much energy potential in the reactors. If we picked the highest-energy orbit to Mars that our fuel supply would allow, we could probably be landing within forty minutes including acceleration and deceleration—except that the acceleration we’d have to undertake would burn out the null-grav units in ten seconds and we’d be smashed into a pulp ten seconds later.”
Tom Barron frowned. “But I thought your antigravity generators were only good for landing and taking off from planetary surfaces.”
“Why? Why should they be limited to that? You measure acceleration in gravities, don’t you? And a human being without protection in a space ship can only tolerate a few gravities for a few minutes.
Without null-G this trip would take us months, and even then we’d have to tolerate weighing four hundred pounds apiece for about half the time. Null-G takes the weight off us and puts it on the ship’s generators, which cut into the total fuel supply but still give us speed. So we balance fuel available against the maximum acceleration gravities the null-G units can handle, and that gives us the highest-energy orbit the ship is capable of and tells us our travel time. See what I mean?”
“I guess so,” Tom said dubiously. “But I still don’t see how you can ever locate yourself definitely relative to anything when you move around the way you do.”
“Well, obviously I have to have a baseline somewhere. We use our central dispatching station at Asteroid Central as a baseline. Otherwise we just plain couldn’t navigate in space. The computer at Central keeps running tabs on every known chunk of orbiting land mass in the solar system, relative to itself in its own orbit around the sun. So at any given instant the main computer can tell where each of the planets is in its orbit, how fast it is moving at the time, how rapidly it’s accelerating or decelerating in its orbit at the moment, and where Asteroid Central is in relation to it. That way any ship that leaves Asteroid Central can blank its own computer and file in its baseline coordinates at that particular point in time and space. It just lifts that chunk of information from the main computer. And then, to get a fix later the pilot just has to calculate back. Of course, every movement the ship makes after leaving Central is automatically filed into its own computer.”
Tom peered at the shiny bank of dials on the control panel. “That must be quite some little computer,” he said.
“It has to be. Its capacity is pretty amazing, but the pilot still has to do some of the work. On Asteroid Central the main computer does it all.” Ben scribbled once more on a card, punched the feeder tape running down into the computer, waited a few moments until the return card dropped down in the slot, and finally began setting the ship’s controls. Then he rechecked the figures, and shook his head. “It’s going to be slow,” he said. “We’re already fifteen degrees out of opposition with Mars, and losing ground all the time. We can do it in another seventeen hours if we accelerate for fourteen of them, and if the null-gravs don’t burn out when we try to slow down in three. But that’s the best we can do.” He made some final adjustments in the dials. “That should do it. Now here we go.” He threw the drive switches, and sank back in the control chair with a sigh. There was a low-pitched rumble from somewhere in the rear of the ship, and a slight vibration beneath their feet; otherwise, nothing seemed to have happened. For a moment or two the star pattern in the view screen shifted slowly, then fixed again. The ship seemed to be standing still in the blackness.
Joyce joined them at the control panel as Ben was setting the dials. Now she said, “What’s wrong?”
“Not a thing,” Ben Trefon said.
“But nothing’s happening, we’re just standing still.”
Ben grinned. “You think so, eh?” He braced his feet, hooked his arm around a shock bar on the control panel, and then turned the null-gravity dial a fraction of a degree. Abruptly he felt the acceleration tugging at his arm; Tom and Joyce Barron began staggering back across the cabin as though drawn by a giant vacuum cleaner. Ben snapped the dial back sharply, and his prisoners jerked forward again, fighting to keep their balance.
“We’re moving, all right,” Ben assured them. “If the null-G’s weren’t working now, our acceleration would be quietly squeezing you through the rear bulkhead into the engine room, so you’d better just pray that nothing goes wrong with our generators.”
Visibly impressed, Joyce Barron stared out the view screen. “So we’re going to Mars.” She hesitated.
“Are there any laboratories there?”
“Just some observation labs, and the Botanical Experiment Station. But we’re not going there. We’re going to my home.”
Joyce looked startled. “You mean you live on Mars?”
“Sometimes.”
“But I thought you people lived in space ships!”
“We do—sometimes. But you can’t grow food on a space ship. You can’t raise children there, either, or forge tools, or manufacture ships. Spacers have homes all over the solar system. It so happens that the House of Trefon has always been on Mars.”
“Trefon,” the girl said thoughtfully. “I never heard a name like that before.” Ben laughed. “Maybe that’s because there isn’t any. I mean, officially. That’s just my short name. On the records I’m Benjamin Ivanovitch Trefonovsky, but that’s too clumsy to use. Ben Trefon works much better.”
The girl was looking at him with distaste. “Then you must be descended from the Russian traitors,” she said contemptuously.
“From the Russian space garrison, yes. From traitors, no. The Trefons have never been traitors.”
“They betrayed their government during the Great War, didn’t they?” Joyce Barron said indignantly.
“Everybody knows that. They conspired with the American and British traitors and sold out their countries when they were needed the most.”
“They refused to burn their home planet to a cinder, that’s true,” Ben said slowly. “Maybe that’s your idea of treachery. But if it hadn’t been for the peace in space, there’d be nothing left on Earth at all, nothing. You wouldn’t be alive and neither would anybody else. But I don’t suppose you’d believe that, with all the lies your government tells you.”
“You can’t deny historical fact,” the girl exclaimed.