Alternately cutting from the outside and the center of the hole, Kemp worked his way downward until his head was below ground level. Rip called a halt. Kemp gave a little jump and floated straight upward. Koa caught him and swung him to one side. Rip stepped into the hole, and Santos gave him a slight push to send him to the bottom. Rip knelt and sighted upward. Kemp had done a good job. The star Rip had chosen as a guide was straight overhead.
He bounced out of the hole, and, as Koa caught him, he told Kemp to go ahead. "Dominico, here's your chance. Get tools and wire. Find a timer and connect up the ten-kiloton bomb. Nunez, bring it here while Dominico gets 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."