Ultimate umbrella

Star Wars: missile defense
Howzit work?
A tough task
When to hit that missile?

The launch of a Minuteman missile. The top two stages of a Minuteman II missile will be used to launch tests of the national missile defense.

This image courtesy of The United States Air Force Space Command.


Harder than hitting a bullet with a bullet?
Minuteman missile
The Why Files pressed space-policy expert John Pike to compare the problem of hitting an incoming missile to something more familiar, but there aren't any good comparisons. He said steering the kill vehicle by on-board rockets toward the warhead would have to be "considerably more precise than a laser-guided bomb. There, you're only trying to hit the right building, and it's stationary. This kill vehicle is trying to hit a target the size of a TV set."

Laser-guided bombs have been extensively tested, but even they are not foolproof, Pike points out.

Rick Lehner, of the Pentagon's ballistic missile office, counters that "we obviously have the technology to locate a warhead in space and collide with it." He bases this assertion on a successful intercept test from 1991, which used technology devised for the Strategic Defense Initiative, as the original Star Wars program was officially called.

Most of the failures, Lehner says, resulted from problems with components not directly related to finding and striking the warhead. "Only two tests made it into the end game [the last few seconds before impact]. One succeeded, and one missed by a short distance," he says.

The next missile defense test is scheduled for August. A total of four tests are supposed to be performed by the summer of 2000, when a decision is supposed to be made about deployment. On June 10, a smaller missile defense system called Theater High Altitude Area Defense (THAAD) finally struck pay dirt -- destroying a test missile after a series of failures.

Hitting the target is one problem. But simply identifying it may be equally difficult. For example, Pike sees "obvious problems" in target discrimination. How would the anti-missile missile's infra-red camera distinguish warheads from spent rocket parts, or, for that matter, weather satellites and random space junk?

Actually, the problem could be more serious than that, since an enemy would likely include decoys -- perhaps as simple as reflective balloons -- that could be mistaken for warheads. Each decoy hit means one less interceptor available to whack real warheads (a problem that also arises if the system redundantly targets a warhead).

Enough caviling. Let's leave the skeptics to talk with someone who believes the time is ripe for missile defense.

One if by land
The simplest argument for building a missile defense is the enormous destructive power of a nuclear warhead or a warhead full of anthrax bacteria. "Something is better than nothing," says Baker Spring, a defense analyst with the Heritage Foundation, which advocates building a defense soon. Since "we are still dealing with the current situation of zero defense," an imperfect defense is still a useful goal.

To the naysayers who claim that any defense would miss too many warheads, Spring has a simple answer. "We don't predict that [the first system to be deployed] will be a permanent and total solution. I don't believe we have told anybody that it would be 100 percent reliable or would be able to address a large-scale attack such as Russia would still be able to mount, or that we don't need other capabilities to deter as well as defend."

Choices, choices. First among equals: when to whack that incoming?

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