Then Rip took a container of chemical fuel from Bradshaw. Working while running, he lashed the two containers together with his safety line. Then he improvised a rope sling so they could hang on his back.
Kemp, meanwhile, assembled his torch and put the proper cutting nozzle in place. When he was ready, he moved over to Rip's side and connected the torch hoses to the tanks the lieutenant carried. Kemp had the torch mechanism strapped to his own back. It was essentially a high-pressure pump that drew oxygen and fuel from the tanks and forced them through the nozzle, under terrific pressure.
When he had finished, he pressed the trigger that started the cutting torch going. The fuel ignited about a half inch in front of the nozzle. The nozzle had two holes in it, one for oxygen and the other for fuel. The holes were placed and angled to keep the flame always a half inch away, otherwise the nozzle itself would melt.
"How do we work this?" Kemp asked.
"We'll get ahead of the others," Rip explained. "Keep up speed until we're running at the forward sun line. Then, when the crystal we want comes around into the shadow, we stop running and work until it spins back into the sunshine again."
Rip estimated the axis on which the asteroid was spinning and selected a crystal in the right position. He had to be careful, otherwise their counterblast might do nothing more than start the gray planet wobbling.
He and Kemp ran ahead of the others. The Planeteers and their prisoners were running at a speed that kept them right in the middle of the dark area.
It was like running on a treadmill. The Planeteers were making good speed, but were actually staying in the same place relative to the sun's position, keeping the turning asteroid between them and the sun.
Rip and Kemp ran forward until they were right at the sun line. Then they slowed down, holding position and waiting for the crystal they had chosen to reach them. As it came across the sun line into darkness, they stopped running and rode the crystal through the shadow until it reached the sun again. Then the two Planeteers ran back across the dark zone to meet the crystal as it came around again. There was only a few minutes' working time each revolution.
Kemp worked fast, and the first hole deepened. Rip helped as best he could by pushing away the chunks of thorium that Kemp cut free, but it was essentially a one-man job.