Mark clapped his hands and turned to Madera. Madera smiled and raised his eyebrows. With an open hand, he gestured to the control panel. Mark nodded his thanks and pressed several buttons. The files changed rapidly at each new command. Then Mark made fists and clenched a few times as if massaging his fingers. Then he raised his hand and prepared to press a button off to the side of the panel.

Suddenly he leaped back a foot, his hands lifted as if he had touched a hot surface. His face was white, his eyes were wide open, and he was breathing hard. His body was trembling as if he were deadly frightened. Zip shot forward, pushing his way through the crowd to reach Mark.

“What is it, Mark? What’s wrong?” His voice was urgent.

“The power plant—it’s thousands of years old!” Mark wasn’t looking at Zip—he was still looking forward, as if his eyes were being drawn to the controls. “Pressing this button...” he stopped and swallowed hard, and blinked twice. “Pressing this button is the last step in activating the rest of the power plant. It should give us the power we need, but—but it’s clear that it hasn’t been activated for thousands of years. There’s no way to tell whether it’s safe. This is a complicated system. If something is wrong,” Mark slowly turned to face Zip, “If something is wrong, if a bolt has slipped into the wrong place, if Zimbardo bypassed a vital circuit somewhere, or if a conduit is stopped up anywhere, all the energy this plant can produce could blow back at us. The entire works could explode into a million pieces.”

Zip looked at the floor for an instant, then looked up again and stared directly into Mark’s eyes. “You’re right, Mark; but there’s no other choice. You have to do it.”

Mark’s exhaled quickly. “Oh, I know, Zip—I know. But as I reached out my hand, I had a sudden chill that our destruction was a second away. It just didn’t feel right. And if this asteroid blows into fragments, then Earth will be peppered with hundreds of devastating impacts!”

Zip slowly turned and faced the silent crowd. Every face was marked with grave intensity. Joe stood at the back, his face drawn and tense.

“You all heard,” Zip said. “But you all know that we have no choice.” No one said anything. A few men dropped their eyes and shuffled their feet. Zip turned to Mr. Madera in silent appeal. Madera nodded very slowly.

Then Mark wiped both hands on his shirt and slowly reached out and pressed the last button.

A distant grinding noise as of gears engaging sounded from far away. There was a whooshing sound as of air filling a giant bag. The grinding sound leveled off into a bare hum. The lights gradually came on.