ments. A little while later, fuel pumps
began to whine somewhere in the tail of the ship. Then the acceleration
dropped to zero as the second-stage thrust was terminated. There was a
series of thumps as explosive bolts released the second stage. The whine
of the pumps dropped in pitch as fuel gushed through them, and
acceleration returned in a rush. The acceleration lasted for a few
seconds, tapered off quickly, and ended. A light winked on on the
instrument panel as the ship announced its mission was accomplished.

Major Harry Lightfoot, fighter pilot, felt a glow of satisfaction as he
saw the light come on. He might not have reflexes fast enough to pilot
the ship up here; he might not be able to survive the climb to intercept
without the help of a lot of fancy equipment; but he was still
necessary. He saw still one step ahead of this complex robot which had
carried him up here. It was his human judgment and his ability to react
correctly in an unpredictable situation which were needed to locate the
warhead from among the cluster of decoys and destroy it. This was a job
no merely logical machine could do. When all was said and done, the only
purpose for the existence of this magnificent machine was to put him
where he was now; in the same trajectory as the missile, and slightly
behind it.

Harry Lightfoot reached for a red-handled toggle switch at the top of
the instrument panel, clicked it from AUTO to MANUAL, and changed his
status from passenger to pilot. He had little enough time to work. He
could not follow the missile down into the atmosphere; his ship would
burn up. He must begin his pull-out at not less than two hundred miles
altitude. That left him one hundred eighty-three seconds in which to
locate and destroy the warhead. The screen in the center of his
instrument panel could show a composite image of the space in front of
his ship, based on data from a number of sensing elements and detectors.
He switched on an infrared scanner. A collection of spots appeared on
the screen, each spot indicating by its color the temperature of the
object it represented. The infrared detector gave him no range
information, of course. But if the autopilot had done its job well, the
nearest fragment would be about ten miles away. Thus even if he set off
the enemy warhead, he would be safe. At that range the ship would not
suffer any structural damage from the heat, and he could be down on the
ground and in a hospital before an