Earth

For longer than he could remember, Stan had heard excited predictions about how nanomachines would transform the world, create wealth out of garbage, build new cities, and save civilization from the dire prospect of ever-dwindling resources. They would also scour your arteries, restore brain tissue to youthful vigor, and mayhaps even cure bad breath. In reality, their uses were limited. The microscopic robots were energy gluttons, and they required utterly well-ordered environments to work in. Even to lay down a uniform crystalline ante

Carefully, he used Alex’s equations to adjust the design, teasing the cylinder into just the right shape to send delicate probes of radiation downward through those fiery circles of hell below, in search of an elusive monster. It was blissfully distracting work.

When the explosion struck, the initial wall of sound almost knocked Stan off his stool. Booming echoes reverberated down the rocky galleries. A scream followed, and a hissing roar.

Men and women dropped tools, rushing to a bend in the cave where they stared in apparent horror. Alex Lustig plowed past the throng toward the commotion. Stan stood up, blinking. “What… ?” But none of the ru

“Get a ladder!” someone cried. “There’s no time!” another shouted.

Negotiating a maze of pipes and wires cluttering the floor, Stan finally managed to nudge past a rank of gawkers and see what had happened. It looked at first as if a steam line had broken, jetting hot vapor across a wall festooned with gridlike latticework. But the wind that suddenly hit him wasn’t searing. It knocked him back with a blast of bitter cold.

Is it just the liquid nitrogen? Stan worried, bending into the frigid gale. Or did the helium line break as well? The first would be a setback. The latter might mean catastrophe.

He managed to join a crowd of techs sheltering behind one of the chemosynthesis vats. Clutching flapping work coats, the others stared toward the tangle of scaffolding, where a broken pipe now spewed cutting cold. Meters beyond that impassable barrier, two figures huddled on a teetering catwalk. The shivering workers were isolated, with no visible way to escape or to reach the cutoff valve atop the towering cryogenics tanks.

Someone pointed higher, near the arched ceiling, and Stan gasped. There, dangling from a cluster of stalactites, hung Alex! He had one arm draped through a gap between two of the hanging rock-forms, just above where they fused. It looked like an awfully precarious perch.

“How’d he get up there?.”

Stan had to repeat the question over the roar of frigid, pressurized gas. A woman in a brown smock pointed to where a metal ladder lay crystallized and shattered amid the jetting frost. “He was trying to get past the jet to the cutoff valve… but the ladder buckled! Now he’s trapped!”

From his perilous position, the young physicist gestured and shouted. One of the techs, a full-blooded Maori from George Hutton’s own iwi, started scrambling for pieces of hardware. Soon he was whirling a heavy object at the end of a cable, sending it flying on an upward arc. Alex missed the tool itself, but caught the cable round his left arm. Bits of crumbling limestone rained from his shaky roost as he used his teeth and one hand to reel in a drill with a rock-bolt bit already in place.

How can he find the leverage to…

Amazed, Stan watched Alex throw his legs around the half-column. Hugging the stalactite, he applied the drill to the strongest section, just above his head. The hanging rock shuddered. Cracks appeared, crisscrossing the pillar at Alex’s midriff. If he fell, he would carom off some toppled scaffolding straight into the supercold jet.

Stan withheld breathing as Alex drove the bit, tested it, and quickly passed a loop of cable through the grommet, giving it his weight just as the greater part of the stalactite gave way, falling to strike the debris below with a crashing noise. The crowd shouted. Dangling in midair, Alex struggled for a better grip while everyone below saw what the tumbling stone had done to his i

Stan breathed again when Alex slipped his shoulders through the loop and let the cable take his weight. Still gasping, the young man turned and shouted over the noise. “Slack!… Pump!”

Two of the techs holding the cable looked puzzled. Stan almost rushed over to explain, but the Maori engineer caught on. Gesturing to the others, he began letting out more cord and then pulled most of it back just before Alex’s feet neared the icy jet. The process repeated, letting out rope, pulling it back. It was a simple exercise in harmonic resonance, as with a child’s swing, only here the plumb was a man. And he wouldn’t be landing in any sandbox.

Alex’s arc grew as the tether lengthened. With each pass he came nearer the supercold shroud of liquefied air, a blizzard of sparkling snowflakes whirling in his wake. He called down to those ma

Then on the next pass — “Three!”

Then — “Two!”

Each time his voice sounded more hoarse. Stan nearly cried out as he saw the arc develop. They were going to release too soon! Before he could do anything though, the men let go with a shout. Alex sailed just over the jet, past the two stranded survivors, to collide with the tangled gridwork atop the centermost cryo tank. Immediately he scrambled for purchase on the iced surface. The woman next to Stan grabbed his arm and hissed sharply as Alex began a fatal slide…

… and stopped just in time, with one arm thrown around a groaning pipe.

A sharp crackling noise made Stan jump back as one of the nearby chem-synthesis tanks crinkled, folding inward from the cold. Fiber-thin control lines flailed like wounded snakes until they met the helium jet, at which point they instantly shattered into glassy shards.

“They’ve cut the flow topside,” someone reported.

Stan wondered, was the helium partial pressure already high enough to affect sound transmission? Or was the fellow’s voice squeaky out of fear?

“But there’s too much already in those tanks,” another said. “If he can’t stop it, we’ll lose half the hardware in the cavern. It’ll set us back weeks!”

There are three lives at stake, too, Stan thought. But then, people had their own priorities. Hands took his sleeve again… this time several senior engineers were organizing an orderly evacuation. Stan shook his head, refusing to go, and no one insisted. He kept vigil as Alex worked his way toward the cutoff valve, hauling himself hand over hand. The pipes were left discolored. Patches of frozen skin, mixed with blood, Stan realized with a queasy feeling.

Centimeter by centimeter Alex neared the collapsed catwalk. One wall staple remained in place, imbedded in limestone. Barely able to see, Alex had to hunt for it, his foot repeatedly missing the perch.

“Left, Alex!” Stan screamed. “Now up!”

His mouth open wide, exhaling a dragon’s spume of crystallized fog, Alex found the ledge and swung his weight onto it. Without pausing, he used it to hurl himself at the valve.