circumstances, his problem was bad. He was hemmed
in on one side by physics, and on the other by arithmetic. The most
probable direction for an attack was from over the Pole. His radar beam
bent only slightly to follow the curve of the Earth. At great range, the
lower edge of the beam was too far above the Earth's surface to detect
anything of military significance. On a minimum altitude trajectory, an
ICBM aimed for North America would not be visible until it reached 83 deg.
North Latitude on the other side of the Pole. One of his interceptors
took three hundred eighty-five seconds to match trajectories with such a
missile, and the match occurred only two degrees of latitude south of
the station. The invading missile traveled one degree of latitude in
fourteen seconds. Thus he had to launch the interceptor when the missile
was twenty-seven degrees from intercept. This turned out to be 85 deg. North
Latitude on the other side of the Pole. This left him at most thirty
seconds to decide whether or not to intercept a track crossing the
Pole. And if several tracks were present, he had to split that time
among them. If too many tracks appeared, he would have to turn over
portions of the sky to his assistants, and let them make the decisions
about launching. This would happen only if he felt an attack was in
progress, however.

Low-altitude satellites presented him with a serious problem, since
there is not a whole lot of difference between the orbit of such a
satellite and the trajectory of an ICBM. Fortunately most satellite
orbits were catalogued and available for comparison with incoming
tracks. However, once in a while an unannounced satellite was launched,
and these could cause trouble. Only the previous week, at a station down
the line, an interceptor had been launched at an unannounced satellite.
Had the pilot not realized what he was chasing and held his fire, the
international complications could have been serious. It was hard to
imagine World War III being started by an erroneous interceptor
launching, but the State Department would be hard put to soothe the
feelings of some intensely nationalistic country whose expensive new
satellite had been shot down. Such mistakes were bound to occur, but the
Launch Control Officer preferred that they be made when someone else,
not he, was on watch. For this reason he attempted to anticipate all
known satellites, so they would be recognized as soon as they appeared.

Accordin