"Means we'd better strap in," said Jonner, suiting the action to the words. "You're in for a short trip to Phobos, Deveet."
Jonner pulled back slowly on the elevator control, and the plane began a shallow climb. At 700 miles an hour, it began to attain a height at which its broad wings—broader than those of any terrestrial plane—would not support it.
"I'm trying to decide," said Deveet with forced calm, "whether you've flipped your helmet."
"Nope," answered Jonner. "Trolling for those fish in Mars City gave me the idea. The rest was no more than an astrogation problem, like any rendezvous with a ship in a fixed orbit, which Qoqol could figure. Remember that 6,000-mile television cable the ship's hauling? Qoqol just shot the end of it down to Mars' surface by signal rocket, we hooked on and now he'll haul us up to Phobos. He's got the ship's engine hooked onto the cable winch."
The jets coughed and stopped. The plane was out of fuel. It was on momentum—to be drawn by the cable, or to snap it and fall.
"Impossible!" cried Deveet in alarm. "Phobos' orbital speed is more than a mile a second! No cable can take the sudden difference in that and the speed we're traveling. When the slack is gone, it'll break!"
"The slack's gone already. You're thinking of the speed of Phobos, at Phobos. At this end of the cable, we're like the head of a man in the control section of a space station, which is traveling slower than his feet because its orbit is smaller—but it revolves around the center in the same time.
"Look," Jonner added, "I'll put it in round numbers. Figure your cable as part of a radius of Phobos' orbit. Phobos travels at 1.32, but the other end of the radius travels at zero because it's at the center. The cable end, at the Martian surface, travels at a speed in between—roughly 1,200 miles an hour—but it keeps up with Phobos' revolution. Since the surface of Mars itself rotates at 500 miles an hour, all I had to do was boost the plane up to 700 to match the speed of the cable end.
"That cable will haul a hell of a lot more than twenty tons, and that's all that's on it right now. By winching us up slowly, there'll never be too great a strain on it."
Deveet looked apprehensively out of the port. The plane was hanging sidewise now, and the distant Martian surface was straight out the left-hand ports. The cable was holding.