The roots were the chutes, each containing the nuclear material — if the information was correct. It was time to verify one part of it. He removed a neutron analyzer from his bag. It, itself, was a short black object, with an LCD display at the bottom. The top held the actual instrument. Radioactive material, because of its constantly unstable nuclear state, was a voracious neutron emitter. That was the quality that made it so powerful. Neutrons racing away from their source struck the nuclei of other atoms and, in simple terms, sliced them open, sending even more neutrons out toward other atoms. In subcritical nuclear assemblies the reaction would never reach the stage where neutrons were continuously bombarding and attaching themselves, only because the mass of nuclear material needed was insufficient. When a precise amount or more was present, the reaction would become self-sustaining — a chain reaction — or, without proper controls, supercriticaclass="underline" the point when physical temperatures overcame subatomic bonds and the critical mass melted.
Joe switched the instrument on and placed it over the bulbous center of the object — the core, if he was correct. There was an increased amount of neutron ‘travel’ as he called it But not exceedingly abnormal. He slowly rotated the instrument on its side, and saw an instant and steady increase in activity.
The neutron analyzer used by NEST was an expensive and miniature model of larger instruments that measured activity in nuclear power plants. Its added feature was that it was directionaclass="underline" It could detect not only the amount of neutrons transiting through two-inch-square gold filaments, but also, by measuring the time between transits through the parallel sensors, it could determine the angle of penetration, and thus the direction.
He kept the analyzer’s body touching the curved top of the device and slid it up to one of the chutes. It was sure, as the readout showed. There was nuclear material in the chute, and not just a small pellet or a depleted slug from a waste site.
“The real thing,” Joe said aloud, though the others were too involved to notice. He moved the instrument to the center between two of the chutes. The readings weakened, then rose again. That meant there was an equal amount of material in each chute. “Damn it, they were right.” It was a thermal reactor, probably with three fourths of a critical mass in each of the chutes.
So if that were the case, how was the thing going to be triggered. Joe examined the reactor — it was that, now — above and below. He crawled around the base of it, and felt with his hands over every exposed portion. Nothing. Just a greasy black exterior. It had to be in the chutes. There appeared to be no obvious work on the cylindrical tubes: They were as smooth as the rest of the thing. The tops…
And there it was. There had been some work done there, and then patched with something: lead and oakum, maybe, or possibly filled with a molten lead. Joe picked at the surface of it with his nails. It was solid, with no signs that it had ever been intended to be opened once constructed.
Son of a bitch. He knew what that meant. It confirmed what everybody had told him — what everybody believed.
What would the trigger be, then? A radio signal? Maybe barometric, set to go off when there was a sudden change in pressure. Like when a bomb goes off at altitude, Joe thought. No, that had too many variables. Whoever had planned this part knew his stuff, so he had to figure for maximum effect. That would mean letting the material come to reaction in a semi steady environment. The reactors would have to be level, or — he checked the lower shape once more — possibly within five degrees of level. A radio signal seemed the most logical, but not reliable. Even a coded signal could be set off by a fluke, or the transmitter might be screwed up. And what if the chutes didn’t all go off? Of course the reactors needed only two to drop for a critical mass, but the waste didn’t make sense. They were going for effect. It had to be a reliable system to trigger it, one that was reliable and consistent.
A timer. A timer. That had to be it! Uniformity in release. Reliability. A system with little chance of interference or false triggers. And…and the time factor. That’s why the guy with the bomb was taking all these chances with the aircraft. It had to be in position on time, or there would be no point in hurrying.
Joe had to smile. Sadr, you brilliant bastard. But now your toy is on my turf. Time to think. Time to—
“Ready your weapons!” McAffee shouted. All the men pulled back the slides on their SIGs, chambering the first round, then did the same to their identical backup weapons which were then reholstered. Antonelli and Quimpo readied their special grenade launchers. They were based on the HK-69 pistol-shaped launcher, a weapon designed for firing 40mm grenades of various types. The round they inserted, though, was quite special and had never been tried in the situation they were going to use it in. But then, they had never even anticipated something like this happening.
The major did a final check of his troops, then went aft.
“You better brace, Anderson.” The civilian’s face was black from something, and so were his hands. “Mask and helmet on until we secure the aircraft.”
Joe nodded. “It’s for real, Major.”
McAffee gave the ugly thing a look, with real distaste in his eyes. “Yeah. I thought it would have to be. You can do your thing?”
“I’ll try. It’s on a timer, I figure, but there could be some backup trigger up there. A radio if there is one. So don’t give anybody with a transmitter a second look.”
“Anybody up there with a gun gets only one look.”
Again, Joe nodded, and the major went back forward. He was a civilian, and these were soldiers, Joe realized. But had they killed before? Had they? he wondered, knowing that some of them might be getting their first taste of death. He just hoped they were all on the right side of the bullet.
Hadad was nervous, but telling himself not to be. The plane was damaged; hurt like a dying whale. And it was climbing so slowly. They were already ten minutes out of the airport, with the coast fading behind them in the darkness, yet the altitude had risen only modestly. Was there something more wrong with the aircraft? Sadr had said that they would need to be at twenty thousand feet for maximum effect, but would they be able to go that high?
The worry must end, Hadad decided. Allah had seen to it that he had come this far, through the small trials of the mission so far. It would all work. He left his seat and exited the cockpit.
“Jesus. It’s almost rime.” Buzz checked over his shoulder.
Hendrickson knew that, and also that the terrorist hadn’t removed that bomb like the other times after takeoff. “Four-Two-Two to U.S. military aircraft.”
There was added silence, then a reply. “What is going on, Four-Two-Two? Why are you on the air?”
The cockpit door opened again before the captain could answer. He looked back. The hijacker was there, as he had been for most of the ordeal, and as before, he had removed the bomb. Hendrickson noticed him sucking on the end of his thumb.
“Why are you watching me, American?” Hadad plopped down into the seat.
Hendrickson turned back around, not bothering to answer.
“You are flying low. Why?”
The first act, Buzz thought.
“With no flaps we have to rely solely on the elevators, and with reduced power we can’t overdo our nose-up attitude. It’s something called a stall condition, if you care.” Take that. The captain thought it was convincing.