Missile Impossible?

Ten...nine...eight...seven..."

On a heavily guarded launchpad at Vandenberg Air Force Base, 125 miles up the Pacific Coast from Los Angeles, a 63-ft.-tall gleaming white rocket sits and waits. Secreted in the nose of the 37-year-old Minuteman II is a 5-ft.-long cone--a mock warhead--and a deflated Mylar balloon. Let's say they are part of an incoming missile from North Korea or Iran. Meanwhile...

https://"Six...five...four..."

About 4,800 miles away on Kwajalein Atoll, perched atop a Pacific coral reef, another rocket sits and waits. Nestled inside its nose cone is a $20 million bullet known as the exoatmospheric kill vehicle. It looks more like a mobile moonshine still than a snub-nosed round, but in the vacuum of space, there are no points for style. Its job is to find and then destroy the incoming "warhead" from Pyongyang or Tehran.

"Three...two...one...Ignition."

This Friday, sometime between 7 and 11 p.m. Pacific time, the Pentagon plans to fire the rocket from California, then fire the interceptor from the Pacific. It hopes the resulting collision will persuade President Clinton to give the order to start building a $30 billion system to protect the U.S. from missile attack. Success could signal the most profound change in U.S. national security since Washington decided to contain Soviet expansionism in 1947. That is why so much is riding on this week's test for the military, its contractors and the space shield's many proponents in Washington.

This decisive test is the third in a planned series of 19 for the Pentagon's projected National Missile Defense system. While Pentagon officers insist there will be future chances to halt its construction, a success this week could make that politically all but impossible. Congress is chafing to fund the system (see following story) and was heartened by the first test, in which an interceptor pulverized a fake warhead last October. In a second test in January, however, the interceptor missed its target by 241 ft. when a cooling line clogged and shut down its heat-seeking sensors. As a TIME investigation shows, little is being left to chance this time. So little, in fact, that this may be a test in name only--an expensive piece of Potemkin performance art to win enormous military appropriations. Exactly what is going to be tested on Friday?

There are virtually no unknowns in the procedure. The Pentagon knows the type of rocket launching the target as well as the nature of the target; it knows how powerful the rocket's engine is, where it is coming from and when it is being launched. The crew launching the interceptor will even get to listen in on the countdown of the warhead's rocket as it takes place. All that is valuable intelligence--and much, if not all of it, would be denied to the U.S. if a rogue state decided to strike. Such advantages "place significant limitations" on the value of the test, says Philip Coyle, the Pentagon's chief weapons tester.

The test favors a positive outcome in other ways. Much of the gear now being tested won't end up in the operational system. The rocket that will ultimately be deployed to lift the interceptor into space--still in development--will shake 10 times as violently as the more gentle boosters scheduled for the first seven tests. While the Pentagon says the shield will defend against "tens" of incoming warheads, all 19 of the Pentagon's tests are against a lone incoming warhead. Jacques Gansler, the Pentagon's top weapons buyer, told Congress last week that the testing program will grow more complex as the system develops. "The system design is solid," he declared. But some skepticism remains on Capitol Hill. Thus every phase of Friday's test will be carefully scrutinized.

Here is what the missile shield's proponents hope will happen--with a lot of apparent help from Pentagon planners:

Five minutes into its launch, the California rocket will release its mock warhead. The accompanying balloon will quickly inflate to its 6-ft.-plus diameter. Traveling less than a mile away from the mock warhead, the balloon is supposed to lure the interceptor away from its intended target. The warhead and the balloon, along with the container in which they rode into space, will reach a top speed of 14,700 m.p.h. and a peak altitude nearly 1,000 miles above the earth.

Within moments of liftoff, the infrared sensors on a Pentagon satellite perched 22,000 miles above the earth should pick up the rocket's flaming plume. The satellite will alert ground-based radars in Hawaii and Kwajalein, which will begin searching the northeastern skies for the intruder. In a fully deployed system, early-warning radars in Alaska, California, Britain, Greenland and Massachusetts would get the alarm. Updates on the target's path will pour into the U.S. Space Command's outpost at Cheyenne Mountain, Colo. Computers there will assemble a "weapons task plan" based on the incoming weapon's trajectory and any decoys trying to fool the U.S. interceptor. Within minutes, the first draft of this electronic map will be zapped nearly 6,000 miles to Kwajalein and into the interceptor's electronic brain.