ove it. It
waggled its wings and changed course.

"We've got to land and be checked for damage," said the co-pilot
negligently. "These guys will circle us and lead the way--as if we
needed it!"

Joe subsided. He still had in his mind the glamorous and infinitely
alluring picture of the Space Platform floating grandly in its orbit,
with white-hot sunshine on it and a multitude of stars beyond. He had
been completely absorbed in that aspect of the job that dealt with the
method of construction and the technical details by which the Platform
could be made to work.

Now he had a side light on the sort of thing that has to be done when
anything important is achieved. Figuring out how a thing can be done is
only part of the job. Overcoming the obstacles to the apparently
commonplace steps is nine-tenths of the difficulty. It had seemed to him
that the most dramatic aspect of building the Space Platform had been
the achievement of a design that would work in space, that could be
gotten up into space, and that could be lived in under circumstances
never before experienced. Now he saw that getting the materials to the
spot where they were needed called for nearly as much brains and effort.
Screening out spies and destructionists--that would be an even greater
achievement!

He began to feel a tremendous respect and solicitude for the people who
were doing ordinary jobs in the building of the Platform. And he worried
about his own share more than ever.

Presently the transport ship sank toward the clouds. It sped through
them, stone-blind from the mist. And then there was a small airfield
below, and the pilot and co-pilot began a pattern of ritualistic
conversation.

"Pitot and wing heaters?" asked the pilot.

The co-pilot put his hand successively on two controls.

"Off."

"Spark advance?"

The co-pilot moved his hands.

"Take-off and climb?" said the co-pilot.

"Blowers?"

"Low."

"Fuel selectors?"

The co-pilot moved his hands again to the appropriate controls,
verifying that they were as he reported them.

"Main on," he said matter-of-factly, "crossfeed off."

The transport plane slanted down steeply for the landing field that had
looked so small at first, but expanded remarkably as they drew near.

Joe found himself frowning. He began to see how really big a job it was
to get a Space Platform even ready to take off for a journey that in
theory should last forever. It was daunting to think that before