A Third Generation of Nukes

The Hazebrook nuclear device that was detonated some 700 ft. below the Nevada desert last Feb. 3 was puny by most measures. Equal to about 40 tons of TNT, a mere .2% as strong as the Hiroshima blast, it would be feeble in a missile warhead. But in space, packed into the closed end of a stubby barrel and tamped down with hundreds of thousands of metal pellets, the low-yield weapon could wreak havoc. Unlike a standard nuclear explosion, which would vaporize the pellets and barrel, this one would spray the pellets through space at speeds up to 100 times that of a high-velocity rifle bullet. These pellets could not only burst the decoy balloons that would accompany a swarm of warheads but also destroy incoming missiles before their warheads were released.

Lieut. General James Abrahamson, director of the Strategic Defense Initiative, has confirmed that such a weapon, which he calls a "kind of nuclear shotgun with little pellets," is being developed under the code name Prometheus, despite SDI's supposedly nonnuclear status. It is only one among several new approaches to nuclear weaponry secretly under study in the nation's bomb-design shops, including the Lawrence Livermore and Los Alamos national laboratories.

The first generation of nuclear weapons were the fission bombs of the 1940s and early '50s. In their quest for more powerful blasts, scientists developed fusion bombs, which became the second generation of nuclear weapons. Now a third generation is being developed that stresses finesse and pinpoint targeting.

Among these new weapons is a bomb that would produce mostly microwaves; exploded in space, it could fry the electronic circuitry and computer chips of an enemy command center. Another bomb would concentrate the force of a nuclear blast on a small target; aimed at, say, the Kremlin, it could leave the rest of Moscow intact. The result, says Physicist Ted Taylor, "is a weapon as different from current nuclear weapons as a rifle is technologically from gunpowder." It is, he continues, "qualitatively a new phase in nuclear weapons development."

Taylor should know: a nuclear-weapons designer at Los Alamos from 1949 to 1956, he later worked for General Dynamics' atomic division and served as deputy director of what is now the Defense Nuclear Agency. In the April Scientific American, he argues that designers can enhance or suppress any of a bomb's destructive effects, including shock waves, heat and various types of electromagnetic radiation.

One advanced version is the Excalibur, already being tested, which boosts the X rays produced by a nuclear explosion. The idea is to use the X rays to power lasers, which would then be targeted at enemy missiles as they fly through space. Taylor argues that microwaves are a better bet for enhancement. Microwaves -- the same kind of electromagnetic emissions that cook TV dinners -- have a longer wavelength than X rays and can scramble electrical systems (hence the warnings to wearers of the early, unshielded heart pacemakers to stay away from some microwave ovens). Unlike X rays, microwaves can penetrate the atmosphere, reaching the earth's surface from space.