There was no time for reflection. Kelly hurried ahead, and Holle followed, clutching her bag.
They got to the foot of the boarding ramp, where ground crew and military, all in NBC suits, checked their boarding tokens and rushed them through retinal checks. One last security check, the last of all. Kelly and Holle got through and joined the line leading up the sloping ramp into the maw of the ship.
And then it struck Holle. “Hey,” she said, panting. “I just took my foot off the Earth for the last time.”
Kelly was striding hard, working the big, deep stairs like an athlete in training. “You need to focus, Groundwater.”
Holle hurried after her. “These moments are unique. I don’t believe this is happening this way.”
“You’ve got years to believe it. Come on. ”
The line slowed as they neared the hatch, some twenty meters above ground level. People jostled as they tried to board. From this vantage Holle could see further out, across the Zone with its frantic activity to the rising curtain of ugly oil smoke, and the terrain beyond. The lights of Gunnison were bright in the dark of a December evening, and plumes of smoke and dust rose up across the wider Hinterland. Over the hiss of the Ark’s giant valves she heard the popping of small-arms fire, the crump of heavier munitions, and, she thought, distant screams. The Ark was the center of a war zone. It was impossible to believe that everything she saw from up here was going to be destroyed as soon as the Ark’s extraordinary engine fired up. But beyond the human sprawl the Rockies rose up, huge and impassive, dark against the sky. They would withstand even the launch of an Orion. She wondered if Earth II would have mountains.
She was approaching the hatch. She took one last deep breath of the air of Earth, but it tasted of gasoline, and the ammonium of the piston coolant, and the harsh metal tang of the Ark’s multiple hulls.
And now she heard shouting from down below. She glanced back. The security barrier at the base of the ramp was failing. Some of the military seemed to have mutinied, and were fighting with cops and ground crew, trying to get on board the ship themselves. Everything was dissolving, she thought.
More planes roared over, impossibly low. She ducked, and hurried inside the ship.
41
“The leak is here.” Liu Zheng unfolded a big paper schematic, and with a pointing finger showed Matt a feed leading from a secondary coolant reservoir. His hand was gloved; they both wore lightweight NBC suits. He had to shout to make himself heard over the hiss of vapor, the roar of engines as buses and trucks raced around the base of the Ark, the urgent yelling of voices, and an ominous clatter of gunfire. “See? Just above this O-ring.”
“Why can’t the automated systems handle it?”
“They froze,” Liu said. “A multiple failure. Shit happens. Well, that’s why we’re here. The leak has to be fixed; without coolant, if one of those suspension pistons overheats and seizes in flight, the Ark will fall out of the sky. You have your tools?”
Matt hitched a pack on his back.
“OK. Take elevator three.” Liu grinned. “This is your moment, Mr. Weiss.” He stuffed the schematics into Matt’s pack. “Go, go!”
Matt ran to the elevator cage, one of a dozen that allowed access to the Ark for maintenance. He slammed shut the gate and grabbed the dead man’s handle that sent the cage rising up into the shadowed innards of the ship. He rose past the curving flank of one of the crew hulls. A wall of white insulation blanket rushed past his face, pocked with maintenance hatches, safety warnings, valve sockets-and handhelds, labeled with upside-down stencils, for use by spacewalking astronauts in the extraordinary future when this ship would be taken apart at the orbit of Jupiter, and reassembled for interstellar flight. He felt light-headed, unreal. He hadn’t slept much in the last week. Since his liberation from jail a week ago he had dedicated all his time to memorizing every aspect of the systems to which he was going to be assigned. He figured he could catch up on his sleep when he was dead. And with the Ark launch being brought back, he had, of course, suddenly lost twelve hours of his life. Quite a big percentage when you only had a day left anyhow.
He looked up, trying to spot the problematic feed. The Ark’s interior was as brightly lit as the exterior, a mass of gleaming metal, pipes, vast tanks connected by ducts and cabling, all contained within the mighty struts of the frame. He saw cameras swiveling, and, clambering over the wall of one of the big crew hulls, a maintenance robot, a thing like a spider armed with a camera for a head, sucker feet so it could climb vertical walls, and a waldo arm with a Swiss Army knife selection of tools.
Still rising, he looked down the flank of the crew hull, and saw, down below, through gaps in the cluster of tanks and pipes, the impassive bulk of the pusher plate itself. An inverted dish of hardened steel, it was itself a beautiful piece of engineering, forty meters across and just ten centimeters thick. The bombs would be detonated below the plate, a weapon five times the strength of the Hiroshima bomb detonating one every one and one tenth of a second. The bombs would be fired into place by the simplest method imaginable, by shooting them down out of a cannon set square in the middle of the pusher plate. The propellant produced by each pulse unit would bounce off the pusher plate, transferring momentum but evaporating too quickly to damage the plate, which would be further protected by a screen of anti-ablation oil, constantly renewed. The resulting thrust would be soaked up by the shock absorber system, immense pistons that rose up above his head, each with a stroke of eleven meters and with a complex dual action that protected the vulnerable parts of the ship from rebound in case a pulse unit failed.
After studying the technical issues from scratch themselves, the Ark’s designers had reverted to something close to what had become the standard design for much of the duration of the original Cold War Project Orion: a four-thousand-ton brute with that mass split evenly between the pusher plate, the ship’s structure, the bombs, and a full thousand tons of payload. By comparison the Saturn V, the booster that had launched Apollo to the moon driven by chemical energies alone, had weighed in at three thousand tons, of which only forty tonnes was payload. It was hard to grasp the reality, even now. When the ship was in flight this whole space would be the scene of huge engineering activity, with splashes of blinding atomic glare coming from all around the rim of the pusher plate, and those pistons shuddering with each mighty stroke.
Looking up now, Matt could see he was approaching the huge tanks of coolant fluid and ablation oil suspended in their frame, and the complex network of pipes that connected one to the other. That was where his leak was. In flight, an ammonia compound was used to cool the pistons after each stroke. The resulting high-temperature compressed gas was then used to power the pumps that squirted a sheet of anti-ablation oil out over the pusher plate before the next detonation, and to thrust the next pulse unit from the charge magazine. Using the products of one stroke to prepare for the next was pleasing for an engineer, a process that reeked of thermodynamic efficiency. But that complexity led to many failure modes.
The light in his elevator cage died, and the cage jolted to a halt.
“Shit.” Matt squeezed his dead man’s switch, and rattled at the cage door. All power to the cage and the pulleys that had been hauling it had been lost. Matt flicked a microphone at his throat. “Liu, it’s Matt.”
As the link came active, Matt heard Liu Zheng break off another conversation. “Go ahead.”
“I lost power, in number three elevator.”
“Wait… I can see. We lost power all down that side, a generator broke down. Damn.” Liu sounded desperately tense. What they feared above all was multiple failure, one problem compounding another. “You still on that coolant leak? You fixed it yet?”