g to the notes he had made before coming on watch, one of the
UN's weather satellites was due over shortly. A blip appeared on the
screen just beyond the 83 deg. latitude line, across the Pole. He checked
the time with the satellite ephemeris. If this were the satellite, it
was ninety seconds early. That was too much error in the predicted orbit
of a well-known satellite. Symbols sprang into existence beside the
track. It was not quite high enough for the satellite, and the velocity
was too low. As the white line swept across the screen again, more
symbols appeared beside the track. Probable impact point was about 40 deg.
Latitude. It certainly wasn't the satellite. Two more blips appeared on
the screen, at velocities and altitudes similar to the first. Each swipe
of the white line left more new tracks on the screen. And the screens
for the adjacent stations were showing similar behavior. These couldn't
be meteors.

The Launch Control Officer slapped his hand down on a red push-button
set into the arm of his chair, and spoke into his mike. "Red Alert.
Attack is in progress." Then switching to another channel, he spoke to
his assistants: "Take your preassigned sectors. Launch one interceptor
at each track identified as hostile." He hadn't enough interceptors to
double up on an attack of this size, and a quick glance at the screens
for the adjacent stations showed he could expect no help from them. They
would have their hands full. In theory, one interceptor could handle a
missile all by itself. But the theory had never been tried in combat.
That lack was about to be supplied.

* * * * *

Harry Lightfoot heard the alarm over the intercom. He vaguely understood
what would happen before his launch order came. As each track was
identified as hostile, a computer would be assigned to it. It would
compute the correct time of launch, select an interceptor, and order it
off the ground at the correct time. During the climb to intercept, the
computer would radio steering signals to the interceptor, to assure that
the intercept took place in the most efficient fashion. He knew RI 276
had been selected when a green light on the instrument panel flashed on,
and a clock dial started indicating the seconds until launch. Just as
the clock reached zero, a relay closed behind the instrument panel. The
solid-fuel booster ignited with a roar. He was squashed back into his
couch under four gees' acceleration.