Exploring the High-Tech Frontier

• Share

(5 of 9)

The ideal weapon? Not quite. In theory, X-ray lasers could be based in space, but that might mean keeping something like 1,400 atomic bombs in low orbits constantly crisscrossing the Soviet Union. Says Coll, rather delicately: "I don't think it's going to be politically acceptable to put bombs in orbit." In practice, the X-ray lasers would have to be launched from earth at the first warning of attack in a "pop-up" defense (they are in fact the only laser devices compact enough for such a defense). To get high enough fast enough, they would probably have to be shot from submarines stationed just off Soviet coastlines.

Now the real problems. Flashing instructions from Washington to submarines in the first moments of nuclear war would be difficult, even assuming the submarines, held in fixed locations, had not been found and sunk by the Soviets in advance of a nuclear assault. If the subs survived and launched their laser-generating bombs, a greater difficulty would arise. All laser beams have trouble cutting through the atmosphere to destroy missiles at the start of their flight, but X-ray lasers are among the least penetrating. They could hit missiles only at the top of the boost phase, and probably would be best used for post-boost or mid-course interception. But that is when the warheads (no longer missiles) are hardest to find because they are hidden amid swarms of decoys.

PARTICLE BEAMS. They are streams of atoms or subatomic particles. In laboratories they can be accelerated to more than 99% of the speed of light by massive devices that can be two miles in length or four miles in circumference. A device that could accelerate the particles to perhaps half the speed of light, which would be poky by laser standards, but adequate for missile defense, might still weigh 500 tons, and hundreds if not thousands of the contraptions would have to be lifted into orbit. Particle beams have even more trouble penetrating the atmosphere than X rays, so they would be more useful for post-boost and mid-course interception than for boost-phase kills.

Even in space, particle beams that carried an electrical charge would be bent off course by the earth's magnetic field. To be effective as missile or warhead zappers, the beams would have to be made neutral, which involves a process of accelerating, aiming and focusing charged particles by electromagnets, then stripping off the charge just before the beams are shot out the end of an orbiting device. Why bother with them then? Primarily because the beams, which work by frying the innards of a missile or warhead with radiation, in principle are more lethal and yield a surer kill than lasers.

One type of charged-particle beam, the electron beam, can operate in the atmosphere, though currently only over very short ranges. Livermore Laboratory has been working on and off since 1958 to develop an electron beam for terminal-phase interception. The current idea is to station a sort of gun on the ground near a group of missile silos or a city and fire electron beams at incoming "physics packages" (a remarkably polite euphemism for atomic warheads) as they re-enter the atmosphere. The beams, however, are hard to aim and control. Not to mention the price tag: Researcher Bill Barletta figures this one small part of a defensive system might cost $20 billion. Says he: "If we can't do it for that price, we shouldn't bother proposing it."