board. He began feverishly to work the computer which in turn would
swing the tight-beam transmitter to the target the computer worked out,
He threw a switch and said sharply, "Calling Space Platform! Pelican One
calling Space Platform! Come in, Space Platform!..." He paused. "Calling
Space Platform...."

Joe had a slide-rule going on another problem. He looked up, his
expression peculiar.

"A solid-fuel rocket can start off at ten gravities acceleration," he
said quietly, "and as its rockets burn away it can go up a lot higher
than that. But 4,000 miles is a long way to go straight up. If it isn't
launched yet--"

Mike snapped into a microphone: "Right!" To Joe he said, "Space Platform
on the wire."

Joe heard an acknowledgment in his headphones. "I've just had word from
the Shed," he explained carefully, "that there may be some guided
missiles coming up from Earth to smash us as we meet. You're still
higher than we are, and they ought to be starting. Can you pick up
anything with your radar?"

The voice from the Platform said: "_We have picked something up. There
are four rockets headed out from near the sunset-line in the Pacific.
Assuming solid-fuel rockets like we used and you used, they are on a
collision course._"

"Are you doing anything about them?" asked Joe absurdly.