Atom Drive Part 5

"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 s.p.a.ce station, which is traveling slower than his feet because its...o...b..t 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 h.e.l.l 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.

"We can make the trip to Earth 83 days faster than the _Marsward_," said Jonner, "and they have only about 20 days' start. It won't take us but a few days to make Phobos and get this cable and the rest of the cargo shot back to Mars. Atom-Star will get its franchise, and you'll see all s.p.a.ces.h.i.+ps switching to the atomic drive within the next decade."

"How about this plane?" asked Deveet. "We stole it, you know."

"You can hire a G-boat to take it back to Marsport," said Jonner with a chuckle. "Pay Mars-Air for the time and the broken ports, and settle out of court with that pilot we dropped. I don't think they'll send you to jail, Deveet."

He was silent for a few minutes.

"By the way, Deveet," said Jonner then, "radio Atom-Star to buy some flonite cable of their own and s.h.i.+p it to Phobos. d.a.m.ned if I don't think this is cheaper than G-boats!"