t 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 can stop running and work until it spins into
the sunshine again."

"Got it," Kemp agreed.

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
counter-blast 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.

As Kemp neared the bottom of the first hole, Rip reviewed his plan and
realized he had overlooked something. These weren't nuclear bombs; they
were simple tubes of chemical fuel. The tubes wouldn't destroy the hole
Kemp was cutting.

He reached a quick decision and called Koa to join them. Koa appeared as
Kemp pulled his torch from the hole and started running again to avoid the
sun. Rip and Koa ran right along with him, crossing the dark zone to meet
the crystal as it came around again.

"There's no reason to drill three holes," Rip explained as they ran.
"We'll use one hole for all three charges. They don't have to be fired all
at once."

"How do we fire them?" Koa asked.

"Electrically. Who has the exp