ts
what he needs."

Kemp was burning his way into the asteroid at a good rate. Every few
moments he pushed another circle or spindle of thorium out of the hole.
Rip directed some of the men to carry them away, to the other side of the
asteroid. He didn't want chunks of thorium flying around from the blast.

The sergeant-major had a sudden thought. He cut off his communicator,
motioned to Rip to do the same, then put his helmet against Rip's for
direct communication. He didn't want the others to hear what he had to
say. His voice came like a roar from, the bottom of a well. "Lieutenant,
do you suppose there's any chance the blast might break up the asteroid?
Maybe split it in two?"

The same thought had occurred to Rip on the _Scorpius_. His calculations
had showed that the metal would do little more than compress, except where
it melted from the terrific heat of the bomb. That would be only in and
around the shaft. He was sure the men at Terra base had figured it out
before they decided that A-bombs would be necessary to throw the asteroid
into a new orbit. He wasn't worried. Cracks in the asteroid would be
dangerous, but he hadn't seen any.

"This rock will take more nuclear blasts than we have," he assured Koa. He
turned his communicator back on and went to the edge of the hole for a
look at Kemp's progress. He was far down, now. Pederson was holding one
end of a measuring tape. The other end was fastened to Kemp's shoulder
strap.

The Swedish corporal showed Rip that he had only about eight feet of tape
left. Kemp was almost down. Rip called, "Kemp. When you reach bottom, cut
toward the center. Leave an inverted cone."

"Got it, sir. Be up in two more cuts."

Dominico had connected cable to the bomb terminals and was attaching a
timer to the other end. Without the wooden case, the bomb was like a fat,
oversized can. It had been shipped without a combat casing.

"Koa, make a final check. You can untie the landing boat, except for one
line. We'll be taking off in a few minutes."

"Right, sir." Koa glided toward the landing boat, which was out of sight
over the horizon.

It was nearly time. Rip had a moment's misgiving. Had his figures or his
sightings been off? His red hair prickled at the thought. But the ship's
computer had done the work, and it was not capable of making a mistake.

Kemp tossed up the last section of thorium and then came out of the hole
himself, carrying his torch.

Rip inspected the