survive the passage through the air and convey its contents intact to
the ground. The contents might have been virulent bacteria or toxic gas,
according to the intentions of its makers. Among its brothers elsewhere
in the sky this morning, there were such noxious loads. This one,
however, was carrying the complex mechanism of a hydrogen bomb. Its
destination was an American city; its object to replace that city with
an expanding cloud of star-hot gas.

* * * * *

Suddenly the sleek cylinder disappeared in a puff of smoke, which
quickly dissipated in the surrounding vacuum. What had been a
precisely-built rocket had been reduced, by carefully-placed charges of
explosive, to a collection of chunks of metal. Some were plates from the
skin and fuel tanks. Others were large lumps from the computer-banks,
gyro platform, fuel pumps, and other more massive components. This was
not wanton destruction, however. It was more careful planning by the
same brains which had devised the missile itself. To a radar set on the
ground near the target, each fragment was indistinguishable from the
nose cone carrying the warhead. In fact, since the fragments were
separating only very slowly, they never would appear as distinct
objects. By the time the cloud of decoys entered the atmosphere, its
more than two dozen members would appear to the finest radar available
on the ground as a single echo twenty-five miles across. It would be a
giant haystack in the sky, concealing the most deadly needle of all
time. No ground-controlled intercept scheme had any hope of selecting
the warhead from among that deceptive cloud and destroying it.

The cloud of fragments possessed the same trajectory as the missile
originally had. At the rate it was overtaking RI 276, it would soon pass
the ship by. The autopilot of RI 276 had no intention of letting this
happen, of course. At the correct instant, stage two thundered into
life, and Harry Lightfoot was again smashed back into his acceleration
couch. Almost absentmindedly, the ship continued to minister to his
needs. Its attention was focused on its mission. After a while, the
ground computer sent some instructions to the ship. The navigation
computer converted these into a direction, and pointed a radar antenna
in that direction. The antenna sent forth a stream of questing pulses,
which quickly returned, confirming the direction and distance to the
oncoming cloud of missile frag