calculated trajectory to determine if the missile was on a ‘threat fan’: meaning if the flight-path could conceivably end in the United States or any allied nation. The initial data showed that the North Korean missile was heading east-south-east, which meant it couldn’t hit mainland America – but the Hawaiian Islands or even Mexico remained possible, though unlikely, targets.
Simultaneously, Buckley’s data links flashed details of the launch to NORAD. Moments later, a klaxon sounded, a light flashed, and a computerized voice announced ‘Missile alert! Missile alert!’ One of the huge vision screens displayed the warning ‘MISSILE EVENT’ in red in the top left-hand corner. In the top centre was the word ‘SECRET’ and below that, occupying most of the screen, was an outline map of the Pacific Rim, with the Korean Peninsula on the left-hand side.
Dominating this display was a large red dot positioned over Ok’pyong, indicating the launch point, and a line pointing east-south-east, showing the missile’s initial trajectory. At the end of the line was a quadrilateral shape, narrow where it joined the line but widening out from that point. This showed the threat fan: the computer system’s assessment of the area within which the missile could land, which was updated every second or two as additional data was processed.
Automated instructions were sent to the Pave Paws phased-array radar control room at Beale Air Force Base in California, and the new X-band radar base on Kwajalein Atoll in the western Pacific, listing the launch and trajectory coordinates and instructing the radars to begin tracking the missile.
The moment the launch data had been confirmed by an automated back-check to Buckley, officers began broadcasting verbal confirmation to supplement the automatic threat warning systems.
‘All stations, this is Brass Hat. Ballistic missile launch detected from Ok’pyong in North Korea. Initial trajectory one two seven degrees true, flight-time is – on my mark – two minutes and fifty-five seconds. Stand by for calculated impact point. This is
One hundred and eighteen seconds after lift-off, and well out over the Pacific Ocean, the first stage of the Taep’o-dong dropped away, its fuel expended, and the second stage immediately ignited. That was scheduled to burn for a further one hundred and five seconds before the third, solid-fuel, stage would fire.
Two hundred and twenty-three seconds after launch, the second stage of the Taep’o-dong disengaged from the missile and began a long uncontrolled tumble to the sea below, and the third-stage motor flared into life. The programmed burn time was one hundred and two seconds, but the fuel was actually expended in ninety-eight seconds. Not that it made any difference.
Three seconds after the sensors had confirmed the engine was dead, six explosive bolts fired on the third- stage/payload junction, and the now-empty tube fell away, taking with it the telemetry transmitter. Now that the third-stage burn was complete, there wasn’t anything the scientists and technicians at Ok’pyong could do to direct the weapon, because the nose-cone hadn’t been designed to be steerable. All they wanted was extreme range, and they’d know the result of the test-flight soon enough.
The warhead on this missile wasn’t a nuclear device or a chemical weapon or anything of that sort. In fact, about all the aerodynamic tip of the Taep’o-dong contained was a dozen hollow metal objects designed as radar reflectors, and a small explosive charge to rupture the nose-cone before re-entry. The cone itself was made from fibreglass with a heat-resistant ceramic coating to be as light as possible, and the weight and shape of the ‘warhead’ had been carefully calculated to ensure reasonable directional stability whilst still achieving maximum range.
The final component was a small transmitter inside a protective heat-resistant canister, locked onto a single frequency, and a radio altimeter that would send it an electronic signal when the canister reached a predetermined height above the ocean. The transmitter would then begin sending out a repeated signal and that, the missile designers had calculated, would be sufficient to achieve the desired result.
One after the other, the telemetry screens ranged in front of the North Korean technicians went blank. Though they all knew in advance that was exactly what was supposed to happen, some of them still looked slightly nervous, as if they might somehow be blamed for the ensuing loss of data from the Taep’o-dong.
Only the commanding officer looked pleased as he picked up the secure telephone to tell Pyongyang that the missile had functioned precisely as they’d planned.
‘Say again,’ General Wayne Harmon demanded.
‘We’ve lost contact with the missile, sir, just after third-stage burnout at around three hundred twenty seconds, and the DSP birds are no longer holding it. I’ve run diagnostics and everything’s in the green. The Pacific Ocean satellite is still tracking residual heat from the burnt-out second and third stages. When we lost it, the missile had reached just over two hundred miles altitude, seven hundred miles down-range and a speed of thirteen thousand miles an hour.’
‘OK,’ Harmon said, ‘so that’s the end of the boost phase and it’s up in the thermosphere. The Pave Paws at Beale should still be tracking it, and we’ll get their feed momentarily. And if Beale can’t locate it, Kwajalein Atoll will pick it up. Project the trajectory, see where the DSP birds think it’s heading.’
On the display screen, a green line appeared, running straight through the quadrilateral and finishing in the North Pacific Ocean about midway between Hawaii and the west coast of Mexico.
‘This reminds me of the Taep’o-dong type 1 they fired back in ninety-eight,’ Harmon observed, ‘except that the trajectory is different and this one looks like it’s going a hell of a lot further. Unless they’ve incorporated some kind of mid-course guidance, it’s no threat to us. This looks in fact like a pretty standard missile test. Keep checking the track and let me know when the DSP birds detect re-entry.’
A few seconds later the first data from the Pave Paws radar was overlaid on the screen, supplemented moments afterwards by the feed from Kwajalein Atoll. The two radars were displaying good solid contacts, and the predict vectors fairly closely matched the track suggested by the DSP satellites.
‘All stations, Brass Hat. DSP missile tracking confirmed by radar. Predicted impact point is between Hawaii and the west coast of Mexico. Trajectory calculations suggest no threat to the US or any allied territory. Initial analysis supports routine test of a three-stage missile, probably a Taep’o-dong type 2.’
The predicted impact point was necessarily vague, depending on a number of different factors, including the missile’s speed, the maximum altitude it would reach before gravity started pulling it back to Earth, and its aerodynamics and ability to withstand the heat generated by atmospheric friction during re-entry. The longer the radars tracked the missile, the more accurate the prediction would become.
‘All stations, Brass Hat. Radar data indicates the missile has just passed the apogee. Refined calculations suggest the impact point will be approximately one four zero degrees west, thirty-five degrees north.’
And then something unexpected happened.
‘Sir, the Kwajalein Atoll radar shows the warhead breaking up.’
‘What altitude?’
‘Around three hundred and twenty miles.’
‘It’s not atmospheric friction, then. Maybe they’ve developed a system of decoys that they’re trying out. Or even an MIRV.’
A Multiple Independently-targeted Re-entry Vehicle is a way of combining several weapons inside a single missile. Typically, the nose-cone is ejected simultaneously with first-stage burnout, to reveal the MIRV ‘bus’ – the device that carries the individual warheads. After passing the apogee, the ‘bus’ manoeuvres using small rockets controlled by an inertial guidance and GPS system to alter its trajectory to match that of the first weapon. Once established, it releases the free-falling nuclear device, manoeuvres again to the trajectory of the second weapon, and repeats the process. Defending against this type of attack is extremely difficult, and such missiles frequently include decoys, with a radar signature similar to the warheads, and chaff – the last being thin strips of aluminium designed to swamp radars. If the MIRV warheads are released soon after apogee, meaning the top of the missile’s trajectory, the spread can be very large.
Ever since the alert began, General Harmon had been in direct communication with both the Pentagon and
