r a ladder rung and braced the other
against a lower rung, hugging the ladder with both arms. "Any time you
say, but kill it if you hear me holler!"

"Then five seconds from my mark--mark!" Mac tightened his grip, and then
sagged backward as the main motors fired. The vibrations shook him
slightly but deeply, and he fought to keep his hold. He felt his back
creak and pop with the sudden surge of weight. Then the motors shut off,
and Mac skidded several feet up the ladder. No matter how fast a man's
reactions were, they couldn't be applied quickly enough to keep him from
starting an involuntary leap after bracing against a suddenly removed
gravity load. "All over, Mac. You O.K.?"

"Guess so, but I feel like a ping-pong ball. How're we sittin'?"

"Just fine," Ruiz cut in. "Find anything?"

"Not yet." Mac started his search anew. Everything seemed in perfect
order up to the turbine pumps. Then, he feared, the trouble was near the
little motors. That was tough, really tough. With the motors retracted
it was next to impossible to get to them, past their hydraulically
operated booms and actuators. Extended, he'd have to go outside. He
cringed from the thought, although he knew that there was little to fear
if he linked himself to the ship.

He peered along the beam of light, searching for some telltale
discoloration in wiring, or a gleaming icy patch which would indicate a
fuel leak. "Might be the firing plugs," he muttered.

"Let's hope not. Where are you, Mac? Maybe you better give us a
blow-by-blow." Logan sounded worried.

"Good idea. Right now I'm at the nine o'clock actuator. Nothing so far."
He looked around himself, forgetting for the moment how he was supposed
to get past the equipment to the other auxiliary motor stations.

"Johnny," he said slowly, "I think you'd best break out the tapes.
Auxiliary motor system; you'll find them under power plant." Months
before, MacNamara had made a complete set of tape recordings of his own
voice, recorded as he made a thorough-going rundown of every system and
its components. This was a personal innovation which his fellow flight
engineers considered folly. Extra weight, they scoffed. Undue
complication. Mac nodded and went on with his impromptu speechmaking; a
professional psychiatrist might have said, correctly, that Mac felt an
unconscious need for supervision, a forgivable deficiency dating back to
his cadet days. Mac simply claimed that the best of men could forget