by Unknown
Melinda said, “Fissile!” Spin’s eyebrows were still raised.
“I calculate that, given appropriate processing and assembly, a device with a yield of perhaps forty kilotons may be fabricated,” Linwood continued.
Melinda said, “Three Hiroshimas.”
“Mm, well, hmm,” said Linwood. “That’s one way of putting it. A device on that order.”
“A device?” Spin asked. “An atomic bomb? Won’t that tend to bend our rear end?”
“Placement will be a challenge, but I should imagine we’ll be quite safe,” Linwood said. “Given ablation and internal collapse of the asteroid, we should be able to arrange things so that our instantaneous acceleration is less than one gee.”
“See, we don’t blow ourselves up, we blow up the rock,” Melinda reassured Spin.
Travis grinned. “You know, Doc, when I was a kid on the ranch, I used to love to tie two firecrackers together and stick ’em in the end of a lead pipe, light ’em both and shoot one out with the other—”
“Yes, Professor Hill, that is the general idea. The essential concept is to steer a portion of the asteroid. By ejecting a significant mass near the sun, the remaining mass—which includes ourselves—will be thrown into a higher orbit, allowing us to achieve rendezvous with Mercury without emerging from hiding.”
“Simple,” Robin said soberly, avoiding Spin’s eye.
“I know it’ll work, Doc, I just know it,” Travis said.
Linwood bent his weighty gaze on the enthusiastic astronaut. “Professor Hill, there is something I’ve considered saying for some months now. Please forgive me if this is an inappropriate moment.”
“Hell no, Doc. What is it?”
“I hate being called Doc.”
23
Early in the morning, Linwood and Robin went into the cargo bay and ripped open the remaining solar probe. It took them only an hour to remove the fuel assemblies from its reactor; with their moderators still in place, the steel-sheathed rods were not warm, not even dangerously radioactive. Robin and Linwood spent another hour scavenging the instrument platform for useful electronics, then carried their booty inside the ship. Linwood, commandeering the geology lab, went to work tearing the uranium fuel assemblies apart. He had four days to build an atomic bomb.
Everest had given birth to a satellite, a plug of rock and ice orbiting at a thousand meters altitude, kept in position above the hole in the asteroid’s side by the thrusters of the shackled first solar probe. Melinda and Travis were in the bottom of that hole. They had redeployed the solar panels above and rigged the laser pulse drill to sink a narrow shaft deep into the heart of Everest, wide enough to permit the passage of the bomb that Linwood was building.
For two hours they hovered nervously above a chaos of splattered lava that coagulated on the walls and floor and occasionally threw up globes of molten rock that Travis and Melinda had to dodge. In the midst of the inferno the squat and ugly drill persisted, like a plumber in a flooding basement, until finally its beam went dark.
“We make it to depth?” Melinda asked.
“That’s what the numbers say.”
“Nifty gadget,” she said. “I hope you sell lots of ’em.”
“Thanks. Let’s get some lunch; I hear it’s ground beef wi’ pickle sauce today.”
“Hey, hey.”
“When we get back to Houston it’s beef Wellington. Baby carrots, Belgian endive, whatever, all that fancy stuff. And all the champagne you can drink. I’m buyin’.”
“Cowboy, you’ve got a date.”
Over the horizon, Starfire crept from hiding in Everest’s shadow. The excavation site that they hoped would be in shadow during the crucial hours of perigee was presently sidelong to the sun. Slowly the ship wheeled, aiming itself with bursts of fire until it was pointed backwards at the gaping hole—poised between the asteroid and its satellite like a billet of shining metal between anvil and hammer.
Sunside, every surface blazed; shadowside, only a lack of stars rendered outlines visible. Everest was a day past the orbit of Mercury; the temperature at its surface had risen to 400 degrees Kelvin, not yet as hot as noon on slow-rolling Mercury, not yet hot enough to melt lead, but getting there fast.
Spin was on the flight deck, sweating. “Twenty meters, did I hear?”
Melinda’s shredded reply came over the comm: “…enty meters, rog…clos…”
“I wouldn’t mind some pad numbers,” Spin growled at Robin, beside him on the flight deck.
“Four-niner over forty. RCS downmode on the maneuver pad.”
“A braking pattern, please,” he said to Robin. Her fingers jabbed at keys while he rocked the joy stick.
Melinda was riding above the engine exhaust coils, sheltered from the sun on the shadowside of the ship. She trained her video camera on the scene that unfolded below her: the maw of the pit opening beneath an obscuring mist of water vapor. Far above her, little attitude jets constantly puffed from the side of Starfire, rocking the ship gently into the depths of the great hole.
“Okay, we’re at sea level. We’re inside the hole,” Melinda said. “Repeat, wing tips are below sea level. We are inside. Clearance nominal.”
Below the mist the vacuum was thick with floating gravel and glittering chips of ice. The debris bounced off the delicate carbon wings of the ship as they edged past the walls. Melinda switched on her helmet lamp and called numbers for many minutes until, finally—
“Ten meters and closing,” said Melinda.
“…opy ten,” said Spin’s voice in her Snoopy hat. The jets spewed vapor, and the column of steel imperceptibly slowed.
“Five meters,” said Melinda.
“Fi…” Spin never sounded tense, even when he had reason to be. Now his tension was evident. If one radiator wing scraped and sustained significant damage, if the magnetic coils of the main engine exhaust slammed into the floor—well, never mind flaming suns and A-bombs.
Melinda watched as the delicate engine coils approached the shaft’s shocked and frozen bottom.
Steering jets intermittently outgassed, playing an intricate tune on a soundless calliope. The massive ship continued to slow, but its inertia was that of an ocean liner drifting into a pier. Finally it stopped, floating mere centimeters from the bottom of the shaft.
“Jesus, Spin.”
The dogged, ugly laser pulse drill squatted below the ship, fixed in gelid slurry.
“…ay again?”
“Clearance approximately one-half meter,” she said. “One-half meter from the bottom of the shaft. Hold it there. We will proceed to secure the ship. Just don’t let ’er move, buddy.”
On the flight deck, Spin let a nostril-flaring grin stretch his face. “Ain’t I hot shit, though?”
“Yes, you is.” Robin smiled.
“Whooeee!”
Travis was descending hand over hand, headfirst down a steel cable, the spark of his helmet lamp marking his passage. A dozen similar cables, scavenged from the solar arrays, draped down Starfire’s sides, almost invisible in the dark. Toggle bolts were sunk into the sides of the shaft. Melinda and Travis laced the cables through the bolts, cradling the ship in a cat’s cradle of wire. The work went on a long time. A small bright cloud of sunlit mist hung forty-five stories over their heads.
When it was over Travis played a hand lamp over the flimsy web that suspended the ship in the shaft. He shook his head dubiously. “Like tryin’ to hog-tie a shark with tenpound test.”
Spin and Robin took the next shift. They moved out of the main air lock, drifting cautiously upward through the tangle of cables and the dense floating debris.
They swam upward toward the light. They passed through a cloud of subliming water. The burgeoning sun flooded the scene with a harsh yellow glare: all around them the surface of Everest was glowing with escaping gas. They immediately adjusted the water flow in their suits and flew on into space, until they reached the far side of the plug that hung in space above Starfire.
> From here they could have looked down upon the whole of the mighty mountain silhouetted against the sun, but they ignored it, laboring instead at the clumsy task of inverting the massive solar probe. Its Z-thrusters had been designed to work in only one direction, “upward”—now they needed the probe to push “downward.” Before they got it rerigged, the air conditioners in their suits were starting to fail. They barely finished the job before fleeing to the shadow of the pit.
From Starfire’s flight deck they reactivated the probe’s thrusters. Slowly the ragged plug nosed back into the hole. They sent a radio signal through the mass of rock to turn off the probe’s thrusters; crumbling and sliding, the plug sank thirty meters before fracturing and jamming fast. Starfire was sealed into the cold and airless pit.
Robin repressurized the ship with a mixture of nitrogen and oxygen approximating air, for what Linwood was doing could not be done in pure oxygen.
Some home-brew nukes are easy to build, some are not. Using material from Travis’s geology kit—solvents, an intense little furnace, a high-speed centrifuge, clever slicers and grinders and polishers, a store of high explosives—Linwood could have tackled any one of several designs, but the more difficult would have taken more time than he could spare. To a man of Linwood’s talents, however, “easy” did not mean unsophisticated.
He considered himself lucky to be working with highly enriched fuel from the solar probe’s small, hot, high-efficiency reactor. Inside its cladding, the fuel was cast in rods of uranium-zirconium hydride. The trick was to burn off the hydrogen, then dissolve the zirconium without dissolving the uranium; a solution of sodium hydroxide did the job, with barium nitrate added to precipitate the uranium. After the hydrogen was cooked out in the furnace, the rest of the six-hour operation was done in a centrifuge at low gees—necessary to keep the reactions going in weightlessness, in the absence of convective currents. The final separation of the heavy uranium from dissolved zirconium took another half-hour of centrifuging, at high gees.
After forty-six hours—four hours off for sleep—Linwood had the pure, enriched uranium he needed. He didn’t need anywhere near the so-called classical amount, the twenty kilos that, when found missing from the inventories of uranium fabrication plants, make their administrators nervous. There were tricks to building an efficient bomb, and Linwood knew them by heart.
His design was classical in its own right, with tropes. Start by holding two subcritical masses of fissile material separated, then drive them rapidly together at the moment of detonation. With Little Boy they did it by firing a subcritical plug from one end of the bomb into a hole in a subcritical donut at the other; the bomb casing was hardly more than a gun barrel.
So sure were the Manhattan Project scientists that the gun-barrel scheme would work that they never bothered to test it; they just shipped it off to Japan. The test they conducted in the sage flats of the Jornada del Muerto, three weeks before Hiroshima, was of a far trickier implosion design, using plutonium, not uranium. It worked too. Curiosity or possibly sheer technical exuberance, masquerading as politics, inspired them to test it again, three days after Hiroshima, on Nagasaki.
Linwood had no intention of building anything so chancy as a pure implosion bomb. It was possible to combine the best features of the gun-barrel and implosion designs, to combine ruggedness, reliability, and moderately good yield. The idea was to bring together two subcritical masses of uranium and at the same time crush efficient neutron reflectors around them. He’d done this sort of thing before, though never in quite such a free-hand fashion.
After Linwood had his shaped masses of uranium—each about half the size of an orange—he set about machining the steel reflectors. That was a bit trickier, for reasons having to do with melting points and shock waves and the shapes that shaped charges take as they are hurled into their targets. Afterward there would be the kneading of the explosives, the welding of the casing—a couple of surplus satellite fuel tanks should do for that—and detonators to be wired, and the synchronizer circuits to be etched and soldered, to ensure that everything went off at once…
His hands were quite happy with this work. He felt he understood what drove sculptors and carvers and ceramicists—the luxury of combining abstract thought with the pleasures of touch, the rush of muscular flexing as well as the tingle of fine manipulation. One might arrange the arts on a scale of sensuousness, he thought. Were dancers starved for ideas? Were photographers starved for touch? No wonder poets loved their pencils, their only point of contact with the material world. The myth of Pygmalion had originated in the seductions of the marble itself, he was sure. All those tales of artists and models…the tension of the intellect which held opposites at a distance snapping in an instant—dichotomy lost, fire in the womb, criticality.
Some children are born with fear; they will not taste, they will not touch, they will not dare. Some are born indomitable; pain for them is instructive, not a deterrent—like Jean and Marcel, his grandchildren, grubbing in the sand after strange creatures. Suggesting that marine biologists are the adult forms of fearless children who would stick their hands into any dark hole, who were cut and nipped and stung repeatedly but were not deterred. And suggesting that bomb makers are the adult forms of fearless children who played with matches and caps and firecrackers, who were blistered and burned, who lost fingers, perhaps, or eardrums, even eyes, but who were not deterred.
Such children, in the adult form, still do not understand deterrence; individually they lead us to discovery, and in groups they lead us to the brink of extinction. Jean and Marcel had inherited perhaps too many of the wrong kind of Linwood’s genes, although certainly their fearlessness had been transmitted by their mother, his daughter, without notably affecting any aspect of her life. Let sociobiology, that pseudoscience, straighten it out if it could; for his part, Linwood had come late to the realization that it was not his right to keep blowing things up and shooting things down because he would not be deterred from having fun.
Sooner or later we adult forms must learn to channel our enthusiasms, he thought. Channel, not eradicate—and only in a limited way for the sake of our progeny, since evidently the world will continue full of dangers. Still, if it came to that, Linwood would rather Jean and Marcel were eaten by sharks than vaporized in war games.
Ahead of all those considerations, Linwood wanted to see his grandchildren again, to discuss their newest discoveries with them. Ahead of that he wanted to take Jeri in his arms. And if he had to build another damn bomb to get home, well…
Besides, it was fun.
24
They had no communication with Earth, not even telemetry; no signal from Earth penetrated the increasing solar interference. Two days from the sun the cameras and antennas they had left on the surface burned out, but not before they had seen the surface of Everest seethe, not before flaming chunks of it had spun off into space and a veil of incandescent haze had been drawn across the stars. Through that haze the sun rose twice in a ship’s day, a gargantuan disk of flame, rapidly enlarging. Then the big screens went dark.
Linwood, seeking a moment’s respite from his lonely work, floated into the wardroom. Travis and Melinda were there, he curled into his corner, she into hers, both of them watching Melinda’s recording of the descent into the shaft. Travis called it her how-to video: how to put a ship in a bottle. Linwood glanced around the cluttered space. The ferns with which the place had been cheerily decorated had withered from neglect, but a tiny lithops, Linwood’s contribution, still thrived.
Melinda looked up at his haggard face. “Anything we can do?”
He shook his head. He occupied himself prying a package of orange drink out of the pantry, while on the big screen, a shining Starfire slid into the pit, a sword into a stone.
“We humorin’ ourselves, Linwood?” Travis asked. “Is this gonna work?”
“Mmm”—Linwood yawned—“’scuse me. The answer is yes. The techniques are well established.”
T
ravis chuckled. “Shoot, you’re just tryin’ to make it sound like you’re havin’ fun.”
From Linwood’s studied expression, they knew he was about to deliver himself of a statement. “It is fun, you see,” he said. “I think that no one who has not sat in on that peculiar game of dares could understand. It used to be a great deal of fun. Making them bigger. Making them smaller. Enhancing neutrons, or x rays, or…just making them do tricks. Making fools of Congress and everyone else who objected…” Linwood rubbed his reddened eyes.
Travis said quietly, “I guess I never understood what you—”
“One day I realized what they were for.” He fought off another yawn. “Then I changed specialties.”
Twelve hours later Linwood tightened the last bolt. The “device,” a steel egg the size of a big garbage can, filled most of the corridor. Both its ends bristled with protrusions resembling spark plugs—the detonators for the hand-molded explosives inside the casing. The thing had to be put together in the corridor because it was too big for the laboratory.
“Hope it can squeeze through the air lock,” Spin muttered.
“Uh-oh. Anyone measured it?” Travis asked sharply.
“Oh my goodness gracious.” Linwood looked stricken. Why hadn’t he thought of that?
If a pin could have dropped…
Linwood smiled a slow, sly smile.
They had to dismantle the laser drill to get access to the shaft. Spin and Melinda and Travis guided the bomb into the shaft. She went first, the bomb went next, and Travis followed, pulling a wire behind him that Spin payed out from the cargo bay. Spin had fixed connectors to the ends of separate spools of cable, scavenged from antenna leads, and sometimes he brought Travis up short while he snapped them together.
The shaft reached deep, to the fault plane that divided Everest—a shaft narrow and dark and exceedingly long, but perfectly straight. So they had no need of maneuvering units; a gentle shove from the edge of the shaft, and inertia carried them through a suspension of ice crystals, steadily on toward the bottom more than one kilometer away. For most of the distance the walls were the familiar frozen-gravel mixture, but they passed seams of pure recrystallized iron, layers of dense black basaltlike stone, and inclusions of compressed ice that had not seen light for a billion years, or four billion…
