Arc Light (21 page)

“
FLASH OPREP
-3
PINNACLE NUDET
,” the female officer said, calmer now, and several other officers began repeating the same words.

“Grand Forks Air Force Base. Near ground level.”

“
FLASH OPREP
-3
PINNACLE NUDET
. Multiple detonations . . . ”

“ . . . Air burst—altitude 5,000 feet—Sawyer Air Force Base.”

“
FLASH OPREP
-3
PINNACLE NUDET
. Nuclear detonations—indeterminate number—Wurtsmith Air Force Base. Altitude: 7,000 feet.”

Lambert ran to the bathroom, clamping his hand over his mouth as his stomach heaved.

The SS-18's warhead streaked downward like a meteor past 125,000 feet, its blunt rounded bottom leading the way. The needle nose was pointed away from the direction of flight, scientists having learned in the early days of space flight that ablation—the process by which the heat-resistant ceramic surface of the warhead's exterior slowly vaporized in the friction of reentry—occurred much less rapidly along a blunt surface than along a pointed one.

The arming system, which had completed prearming before the missile left its silo, was now beginning the final arming sequence. Accelerometers integrated into the Environmental Sensing Device had measured the stresses of launch, the minutes of weightlessness after the three boosters' burns were completed, and then the deceleration through the reentry phase. All matched the tiny computer's expectations. An outside pressure switch in the ESD had sensed the near vacuum of low earth orbit as and when expected, and now detected the growing weight of the atmosphere.

All appeared normal, and the final locks were released. The computer sent a brief pulse of electricity down a circuit running to the warhead's fusing system, and the warhead was armed. The fusing system now began a steady signal to the firing system to charge its battery with sufficient energy to power the detonators when the time came.

Two altimeters began estimating the warhead's altitude. The first measured air pressure through a tiny hole on the warhead's side. The other was a more sophisticated radar unit in the base. The computer checked both against the inertial guidance system's estimate. When the three altimeters simultaneously registered an altitude of 80,000 feet above mean sea level, the fusing system directed a test signal to the firing system. The firing system in turn sent a low energy signal to the dozens of firing circuits connected to detonators embedded in high explosives deep inside the warhead. The circuits
all returned a positive test signal. All was ready. The firing system waited on the fusing system, and the fusing system waited on the three altimeters. All waited for the onrushing ground.

The large hangar was alive with activity, NCOs shouting to the thousand-odd troops who remained awaiting transport. They were checking one another's chemical protective gear or just beginning to make small shelters for themselves out of packs and bags, most crammed against the walls as they curled up on the cold concrete floor.

“Keep your eyes closed!” the base commander yelled, standing there in shirtsleeves, his hands on his hips as he bellowed out his commands. “Open your mouths and jam your fingers in your ears!”

He looked at his watch.
Not long now,
he thought.
Just gotta get ‘em through these last coupla minutes.
He looked out on the mass of soldiers who were growing still in their positions. They were all huddled together, he noticed, none off by him- or herself. No loners, not at a time like this. He felt the urge to join them, to crawl into the piles of arms and legs and lie down with them. There was a strange emotion welling inside his chest, and he swallowed hard as his eyes watered. He swallowed again as he walked down the line of soldiers along one wall. “Hug your knees to your chest! Put your face in your knees!”

The SS-18's warhead had been targeted to detonate at 4,500 feet above ground level directly over the air base, but the trajectory had been misshapen by the Arctic nickel dome and it plummeted toward the ground several hundred yards off to the side of one of March Air Force Base's runways. When the warhead reached 4,500 feet above ground level at the airfield, the final electrical impulse was delivered by the warhead's fusing system to its firing system. The dozens of firing circuits were opened, and the current stored in the now charged battery flowed into the detonators, which popped with not much more energy than a powerful firecracker.

As the warhead passed 4,497 feet above ground level, the high explosives in which the detonators were embedded ignited in the heat of the small explosions and began an extremely fast burn. The rate of advance of the explosives' reaction zone was so great as to exceed the velocity of sound in the unreacted material, the rate of deflagration so great as to be known to nonscientists as an explosion.

As the warhead fell another two feet, the shell of high explosives completed its burn. If it had been possible to take a snapshot of the exterior of the warhead at that moment, nothing unusual would have been noticed, as the explosives were shaped in such a
way as to direct their energy inward. The wave of wasted backblast had not built up pressure on the outer walls sufficient to warp the warhead's shape. The pressure wave, however, inside the “pit”—the shell of explosives surrounding the warhead's core—flew toward the exact center of the sphere at supersonic speeds. The wall of pressure pushed in front of it the uranium 235 around which the explosives had been wrapped.

With every inch of the warhead's descent, the compression of the uranium 235 inward continued. As the gaps between the atoms of compressing U-235 were reduced, the 235 neutrons released from the “explosions” of the inherently unstable and “decaying” uranium atoms began to strike other atoms. More atoms began to burst, sending still more subatomic shrapnel outward to hit or miss its neighbors randomly. Fission had begun, and the laws of statistics defined the process. The more dense the compacting U-235 became, the lower the chance that the neutrons would fly through the gaps and out of the warhead without causing damage to their neighbors.

At an altitude of 4,494 feet, the core of U-235 reached critical mass. From that moment forward, no further compression of the core was needed. Each time an atom of U-235 disintegrated now, more than one of the surrounding atoms of U-235 was, on average, being broken apart.

The rate of radioactive decay began doubling, and then doubling again and again as the subatomic matter shattered atoms and sent still more matter flying outward. The growth was exponential. It was a chain reaction.

With each atom's disintegration, a tiny amount of electromagnetic energy was released. The amount of energy released is measured by temperature, and before the warhead had streaked through the air another foot, the temperature created by the fission reaction had climbed to 1 million degrees at the very core of the warhead. Now, the real explosion began.

The fission or “atomic” explosion had merely been a detonator of its own, creating the heat to ignite a “thermonuclear” reaction. Everywhere the lick of million-degree heat found two atoms of ever present hydrogen, the two atoms' nuclei fused into one atom of the heavier element helium. Since the total energy confined within two hydrogen atoms slightly exceeds the energy of one helium atom, the difference is released on fusion in the form of still more energy. These brief pulses of energy were powerful, their wavelengths the shortest measured along the electromagnetic spectrum. They were gamma rays, and the temperature of the gamma rays released in the fission reaction paled in comparison to the temperature of the thermonuclear burn.

The thermonuclear burn wave expanded outward from the warhead's core at tremendous speed, riding the crest of a 20-million-degree wave of gamma rays. The burn wave slammed into the only barrier between it and the still undisturbed shell of the black warhead: a blanket of uranium 238 called the “tamper,” which was wrapped around the warhead's “pit.” The tamper absorbed and greatly reduced the gamma rays burning outward from the pit, reducing the “prompt radiation” produced by the newer model, relatively “clean” Russian warhead. As the temperature in the tamper rose, however, the U-238, normally stable, began to decay, and a new fission reaction began.

The third and final phase of the “fission-fusion-fission” weapon began as the tamper exploded, the last stage more than doubling the explosive force of the warhead.

The world of March Air Force Base's commander alit in an intensely white flash as the heat vaporized the aluminum upper walls and roof of the hangar. He felt the sensation of heat on his exposed neck, which immediately grew to searing pain as if a hot iron had touched him there. His eyes jammed shut against the intensifying glare.

An expanding sphere of plasma, atoms of gas in the atmosphere around the artificial sun violently “ionized” as they were stripped of their electron shells, pushed the un-ionized air around it outward at a tremendous rate. The border of the shock wave was as clearly defined as the sphere of a soap bubble as the wave propagated outward in all directions, slamming first into the ground directly beneath it. The ground itself rippled under the blow like the surface of a still pond into which a stone had been thrown. Liquefaction of the soil occurred, the solid earth behaving like a liquid before settling moments later.

Outward the seismic ripple radiated, the speed of its travel through the dense earth exceeding the speed of the wave through the air. A longitudinal compression wave, the “P” or primary wave, combined with the shearing transverse and bucking surface waves in the earth to shatter the concrete blocks of an electrical substation feeding power to the runway lights.

Before the unmelted blocks on the far side of the small building could fall to the ground, however, the atmospheric blast wave, a wall of compressed air, surged across the earth and obliterated any trace of the structure above foundation level.

The fireball that formed outside of the plasma sphere began to rise into the air above ground zero at a rate of hundreds of feet per
second. Initially sharply defined by the luminous shock front, the fireball now was deteriorating into a ragged ball as it ignited and burned the air itself all along the radiation front.

On ground level, powerful winds—the “dynamic pressure” of the blast—spread outward, forming a base surge moving behind the blast wave at 290 miles per hour.

The ground bucked up under the base commander twice in rapid succession, the first breaking both ankles and leaving him unsupported in midair and the second striking upward at the soles of his feet and shattering the tibia and fibula of both shins. The first pulse was the direct shock and the second the echo off the base rock lying 160 feet beneath the earth's surface. At the same moment the blast wave swept over him, instantly shooting the pressure of the air to over twenty pounds per square inch, and his eardrums burst with a pain like ice picks jammed into his ears. He had time to scream as the howling gale erupted full blown and the pressure continued to rise. He was swept off his wobbly stance, and he clawed at the air for an anchor.

As the fireball floated upward through the air about one mile from the hangar, it peeked over the low concrete-block walls ringing the hangar and shone its radiant energy directly onto the exposed skin of the base commander, which instantly rose to several hundred degrees Centigrade. Over and over he tumbled, his hands and face flash burning and every blow of his body on the concrete floor causing damage that was quickly growing sufficiently traumatic as to be fatal, his world a spinning blur of darkness and silence. Pain erupted from every corner of his body as melting strips of aluminum and small pieces of concrete blasted off the hangar's walls tore into him like buckshot.

Most damaging of all, however, was the crushing weight of the atmosphere. As the pressure exceeded thirty pounds per square inch, his lungs were emptied of air and his organs began to burst and hemorrhage in a rapid progression toward death. He mercifully lost consciousness before the radiant heat of the fireball, now shining directly onto his body, raised the temperature of first his skin and then the bone and tissue that composed his body above their burning points, and reduced much of him to the elements. Before the blast wave had swept him across the hangar floor to the far wall, little remained of the man.

Just as quickly as the base surge had washed outward across the surface, the afterwinds reversed direction and scoured back across the earth toward ground zero. The concrete blocks forming the base
of the hangar's wall, which had stubbornly stood against the explosion, gave way to the implosion that followed seconds later as the nuclear fireball gulped oxygen to sustain its flames. The afterwinds sucked inward by the updrafts associated with the rising fireball fed a brief but fierce firestorm around ground zero. Flammable materials that were heated above the burning point had been starved for oxygen as the main burn of the explosion fed itself, but now they were flooded with oxygen and flared. Grass and wood burst into flame and were sucked up into the air as ash. They never reached the fireball of the airburst, however, and therefore fell back to earth without being irradiated.

Almost no “fallout” was released to contaminate the earth from the relatively clean airburst, but the effective yield of the SS-18's warhead was right at the 550 kilotons at which it was rated, substantially the same as the yields of the eight other warheads that burst high in the air over March Air Force Base within the next thirty-five seconds, extinguishing all life within a radius of nine miles of the base.

The eerie drone of the Emergency Broadcast System had grown familiar over the car radio. Melissa Chandler kept looking into the rearview mirror at the air base where David said his flight would depart, which was also in the general direction of downtown Los Angeles. Was he gone already? And if so, where? Was he still there, close, and she had just passed him in the night?