Reaching that kind of rotation isn’t easy. An enrichment centrifuge must be carefully balanced and precisely controlled as it spins faster and faster.
Several critical speeds-speeds where the rotor will begin to vibrate dangerously-must be negotiated before it can reach its operating rpm. End dampers can help reduce these vibrations, but they become uncontrollable if the machine contains a significant amount of uranium hexafluoride gas as it cycles through any of these critical speeds.
All of Pelindaba’s spinning centrifuges were full of uranium hexafluoride gas when the plant lost power.
In fractions of a second inertia and drag were at work. Rotors spun slower and slower. And as the machines decelerated, their carbon-fiber walls began to flex, wobbling about like wet noodles-distorted by the gas trapped inside.
Most of the twenty thousand uranium-enrichment centrifuges shattered simultaneously-hurling carbon fiber fragments spinning at more than a thousand miles an hour into the protective casings surrounding each machine. Each crashing centrifuge sounded exactly like a large-bore shotgun being fired just a few feet away.
Some of the casings ruptured, and other machines were thrown off their floor mountings, tearing violently away from the piping connecting each enrichment cascade. Immediately, yellow clouds of highly corrosive uranium hexafluoride gas began spewing out into the cascade hall-spraying from the mangled centrifuges themselves or from hundreds of ruptured feed, waste, and product pipes dangling overhead.
The gas started turning into a solid as soon as it hit room temperature and pressure, but not soon enough for some of the technicians unlucky enough to be trapped inside the darkened maze of broken piping. Several scientists and engineers ran screaming for the emergency exits clutching badly burned faces. Others died moaning, crushed beneath fallen equipment.
South Africa’s uranium-enrichment plant had been wrecked beyond repair for years.
HEADQUARTERS, 2/75TH RANGERS, NEAR THE SWARTKOP MILITARY AIRFIELD
CONTROL TOWER
Scarcely a kilometer south of Pelindaba, Swartkop Military Airfield was also under attack.
Bullets had smashed every window in the Swartkop control tower, and grenades had ignited several fires that were slowly taking hold inside-filling rooms and corridors with thick, choking smoke. Bodies littered floors and stairwells. Most of the dead wore the dark blue uniform of the South African Air Force.
Lt. Col. Mike Carreffa ran out the control tower door with one hand holding his helmet on and the other clutching his M 16. His radioman and headquarters troops were right behind him.
Swartkop Airfield was a mess. Three turboprop transport planes and a fuel truck sat ablaze at the far end of the flight line. Closer in, wrecked cars and trucks dotted the base’s parking lot and access roads.
Parachutes fluttered in the breeze, abandoned wherever his men had landed. Collapsed mounds of torn, smoking sandbags showed where the
Rangers had overrun South African positions in bitter, hand-to-hand combat.
Carrerra frowned. The Citizen Force company assigned to defend Swartkop had put up one hell of a fight. Bright white flashes and the harsh rattle of machinegun fire near the airfield’s huge, aluminum-sided hangars reminded him that his assessment was somewhat premature. South Africa’s reservists were still putting up a hell of a fight.
“Colonel, Sierra One Zero’s on the horn.” His radioman ducked as a mortar round burst on the tarmac ahead of them.
He took the offered mike.
“Go ahead, Sierra One Zero.”
“Do you have that runway clear yet?” Carreffa recognized the clipped
Northeastern accents of the colonel flying the lead MC-141. The ten
American jet transports were circling in a tight pattern over Pretoria and its adjoining airfield, waiting for confirmation that it was safe to land.
“Negative, One Zero. Estimate five minutes before we can bring you in.
Will advise. Out.”
Karrumph. Another mortar round tore up dirt and gravel one hundred meters to the left. Carrerra took his thumb off the transmit button and motioned his senior sergeant over.
“Ike, get on the platoon net and tell Sammy I want those goddamned mortar pits cleared pronto. We’ve got some birds up there anxious to get down on the ground. Got it?”
Carrerra led his headquarters troops across the tarmac toward the fighting raging near Swartkop’s aircraft maintenance hangars. He’d brought five hundred men into this battle. He had a lot fewer left now, and the 2/75th needed every rifle it could bring to bear.
CACTUS SAM LAUNCHER, SWARTKOP MILITARY AIRFIELD
The last surviving SAM launcher assigned to defend Swartkop from air attack sat motionless on a low bluff overlooking the airfield. Brown, tan, and black camouflage netting softened the four-wheeled vehicle’s rectangular, boxy shape-making it look more like a boulder or a clump of dried brush than a missile carrier.
Three men crowded the launcher’s tiny red-lit control compartment.
“Well?”
The short, tight-lipped South African Air Force warrant officer manning the vehicle’s target acquisition and firing board flicked one last switch and shook his head.
“Nothing, Lieutenant. I’m not getting any data from
Cactus Four. Either they’re dead or the cable’s been cut.”
“Damn it!” His taller, younger commander pounded the darkened instrument panel in frustration. Then he took refuge in standard procedure.
“Switch to optical tracking, Doorne. “
“Yes, sir. ” Warrant Officer Doorne’s nimble fingers danced across his control console. A TV monitor slaved to a camera mounted atop the vehicle lit up, showing a wide angle view of the star-studded night sky outside.
Something moved ponderously across the sky, blotting out stars in its path. Doome tapped a key and and focused his
TV camera on the airborne intruder. A big, four-engined jet was already turning away for another orbit over the city.
“Target locked in,
Lieutenant!”
His commander stared at the image on his screen. South Africa didn’t have any planes that looked like that. The bogey must be an enemy.
“Fire!”
The vehicle shuddered and rocked back as one of its missiles roared aloft on a pillar of glowing white flame, accelerating rapidly toward its maximum speed of Mach 2.3. The missile arced toward its target, guided by Warrant Officer Doome’s joystick.
Optical tracking permitted South Africa’s Cactus SAM launchers to attack enemy aircraft even if their fire control radars were out of action or being jammed. The system worked very much like a child’s video game. An onboard digital computer translated a human controller’s joystick movements into flight commands and radioed them on to the missile. All he had to do was hold the cross hairs of his TV sight on the target and the computer would steer the SAM directly into its target. Best of all, optically guided missiles couldn’t be jammed or spoofed away by flares and showers of chaff.
The system wasn’t much use against fastmoving attack aircraft or fighters coming in head-on or crossing at a sharp angle. Human reflexes simply hadn’t evolved to cope with closing speeds measured at nearly two thousand miles an hour. But the C-141 known as Sierra One Four was a huge, lumbering target flying in a wide circle at just four hundred knots.
Two hundred meters downslope, a Ranger fire team leader saw the missile launch and dropped the data cable he and his men had been following uphill.
“Incoming!”
The American soldiers dove for the ground as the SAM flashed past not far overhead-trailing smoke and fire. Spitting out dirt, the fire team leader reared up onto his knees. Get the bastards!”