the whole
asteroid disappear, or else we have to conjure up a space cruiser out of
the thorium. Otherwise, we have a little more than an hour before we're
either prisoners or dead!"

CHAPTER THIRTEEN - PERIL AT PERIHELION

Sergeant-major Koa had made no comment since notifying Rip of the call
from Terra base. Now he asked thoughtfully, "Lieutenant, can the Connie
launch boats this close to the sun? Won't the sun's pull suck them right
in?"

Corporal Pederson scoffed, "Naw, Koa. If sun's gravity be that strong, it
pull us in, too."

"Not quite, Pederson," Rip corrected. "Koa is on the right track. The pull
of the sun is pretty strong. But I don't think it's strong enough to
capture boats."

He had figured the asteroid's orbit to pass as close to the sun as
possible while maintaining a margin of safety. He had wanted to use the
sun's gravity to pick up speed. His regular star sightings had told him
several days before that the sun was dragging them.

But Koa had started a train of ideas running through Rip's head. If they
could get close enough to the sun so small boats would be unable to break
free of its gravity, the Connie wouldn't dare send a landing force. The
powerful engines of a cruiser could break loose from Sol's pull, but not
the chemical jets of a cruiser's boats.

Rip got his instruments and pulled out a special slide rule designed for
use in space. He had Koa stand by with stylus and computation board and
take down figures as he called them off.

He recalculated the safety factor he had used when deciding how close to
put the asteroid to the sun, then took quick star sights to determine
their exact position. They were within a few miles of perihelion, the
point at which they would be closest to Sol.

Rip tapped gloved fingers on his helmet absently. If they could blast out
of the orbit and drive into the sun ... he estimated the result. A few
miles per second of extra speed would put them so far within the sun's
field of gravity that, within an hour or so, small boats would venture
into space only at their peril.

He reviewed the equipment. They had tubes of rocket fuel, but the tubes
wouldn't give the powerful thrust needed for this job. They had one atomic
bomb. One wasn't enough. Not only must they drive toward the sun, they
must keep reserve power to blast free again. If only they had a pair of
nuclear charges!

He called his Planeteers together and outlined the problem. Perhaps