Not bright enough? An airborne laser will be unable to deal with most ICBMs, a new report concludes.

Early Strikes Against Missiles Doomed

WASHINGTON, D.C.--A key component of the U.S. National Missile Defense plan is a pipe dream, according to a new study by the American Physical Society (APS). At a press conference today, the authors of the report shot down arguments for intercepting ballistic missiles in the early phase of their flight, calling the strategy unworkable.

APS has addressed the controversial subject before. In 1987, it trashed the Reagan Administration's "Star Wars" vision of missile defense, saying that a missile shield made of space-based high-energy lasers and particle beams was well out of technological reach. Since then, the latest incarnation of missile defense, particularly the task of shooting down a warhead falling to Earth, has come under fire as being easily defeated and beset by huge technical problems (Science, 16 April 1999, p. 416). But some prominent experts, such as IBM's Richard Garwin, thought that catching missiles on their way up might be easier. This week's report says that task would still be nigh impossible.

The key problem with any missile defense system, whether it employs land-, sea-, air-, or space-based rockets or an airborne laser, is the short time between the launch of a ballistic missile and the time its engine burns out. All told, there are about 100 seconds in which to engage and destroy a missile hurtling upward, the report says. This almost always means that the interceptor has to be positioned unrealistically close to the launch site, especially when the target is a fast, solid-fueled missile. Even airborne lasers would be all but useless, the report explains, with too short a range and too little power.

The report delves into other problems with boost-phase missile defense, including the unpredictable nature of an ICBM's path while its engine is firing and the difficulty of tracking and intercepting the target. Then there are the inevitable technological advances by the enemy. According to U.S. intelligence estimates, North Korea and Iran might develop solid-fueled rockets within a decade or two. That means any system that can't intercept them will "risk being obsolete when deployed," the report says.

"The objective [of the report] was to let you draw your own conclusions," says former APS president William Brinkman. "But the conclusions are fairly clear to anyone who wants to look."

Related sites
The full report
Information about early missile interception from the Missile Defense Agency

Posted in Physics