fell to on his breakfast. The thunderous noises of the pushpots
taking off made the mess hall quiver. Joe said between mouthfuls: "Funny
way for anything to take off, riding on--it looked like a truck."

"It is a truck," said Talley. "A high-speed truck. Fifty of them
specially made to serve as undercarriages so pushpot pilots can
practice. The pushpots are really only expected to work once, you know."

Joe nodded.

"They aren't to take off," Talley explained. "Not in theory. They hang
on to the Platform and heave. They go up with it, pushing. When they get
it as high as they can, they'll shoot their jatos, let go, and come
bumbling back home. So they have to practice getting back home and
landing. For practicing it doesn't matter how they get aloft. When they
get down, a big straddle truck on caterpillar treads picks them up--they
land in the doggonedest places, sometimes!--and brings 'em back. Then a
crane heaves them up on a high-speed truck and they do it all over
again."

Joe considered while he ate. It made sense. The function of the pushpots
was to serve as the first booster stage of a multiple-stage rocket.
Together, they would lift the Platform off the ground and get it as high
as their jet motors would take it traveling east at the topmost speed
they could manage. Then they'd fire their jatos simultaneously, and in
doing that they'd be acting as the second booster stage of a
multiple-stage rocket. Then their work would be done, and their only
remaining purpose would be to get their pilots back to the ground alive,
while the Platform on its own third stage shot out to space.

"So," said Talley, "since their pilots need to practice landings, the
trucks get them off the ground. They go up to fifty thousand feet, just
to give their oxygen tanks a chance to conk out on them; then they barge
around up there a while. The advanced trainees shoot off a jato at top
speed. It's gauged to build them up to the speed they'll give the
Platform. And then if they come out of that and get back down to ground
safely, they uncross their fingers. A merry life those guys lead! When a
man's made ten complete flights he retires. One flight a week thereafter
to keep in practice only, until the big day for the Platform's take-off.
Those guys sweat!"

"Is it that bad?"

The pilot grunted. The co-pilot--Talley--spread out his hands.

"It is that bad! Every so often one of them comes down untidily. There's
something the matter w