The door SDI won't shut.

• Author: Hammer, Charles
• Position: The history of defensive weapons shows why Star Wars won't save us

THE DOOR SDI WON'T SHUT

The proposed Star Wars defense isalmost always diagrammed from a meteor's viewpoint, showing a sky full of orbiting gee-whiz weapons that neatly zap ballistic missiles as they blast off from the Soviet Union.

Yet none of this tangle of kinetic kill vehicles,hypervelocity guns, x-ray lasers, particle beam generators, surveillance satellites, and mirrors is ever shown blowing up a relatively ordinary weapon that could destroy our cities and industries almost as well as ballistic missiles could: bombers.

The Reagan administration would undoubtedlyprotest that some of the technology that comes out of SDI surely could be used some day to protect against these bombers (or their unmanned cousins, cruise missiles). But even Star Warriors admit that most of the exotic gizmos now being discussed aren't even theoretically capable of working in the atmosphere. The few that might be made to work could be rather easily countered.

Instead, we'd be defending ourselves againstbombers and cruise missiles with more conventional arms. But the record of this kind of defense is pretty poor; the best defenses have never been able to stop more than a fraction of even a weak air offensive. When you talk about conventional bombs, percentages may count for something; for nuclear warheads, they are meaningless. Until someone figures out how to stop all the planes, the problem of stopping ballistic missiles is irrelevant to the protection of the American population. never has a large-scale, determined attack by ordinary aircraft been stopped to any degree that would make difference in a nuclear war.

Real world glitches

In 1942, 163 Liberator bombers raided the Germanoil refineries at Ploesti, Rumania. Fifty-two of them were shot down in a brilliant performance by the Luftwaffe and German antiaircraft gunners. That was one of the worst losses in any air raid in any war. Yet two-thirds of the planes still dropped their bombs and returned to base. For all the technological improvements since then, defenders have seldom stopped more than 10 percent of attacking bombers.

One reason planes get through is that pilotsrelish shooting first at the people who are shooting at their planes. In 1951, the North Koreans and Chinese communists tried to repair an airfield at Pyongyang that was ringed by more than 100 antiaircraft guns. Forty-six american Shooting-Star jets swooped in one day to pound the fields with bullets, bombs, and rockets. Twenty-one four-engine B-29s bombed through the rising dust to complete the destruction. Not a single American bomber was damaged.

But we weren't the only ones getting throughthat era's defenses. Robert Jackson, in his air War Over Korea, describes how the communists regularly bombed our airfields at night with Russian Polikarpof-2 Biplane Trainers. These "bedcheck Charlies" created little radar image and flew too low and slow for our...