Crucial test for US missile defence system

2019-03-06 06:07:01

By Jeff Hecht On Saturday, the Pentagon will repeat a test of its controversial national missile defense system that failed a year ago. The goal is the same, to hit and destroy a dummy target at an altitude of about 225 kilometres, but the stakes have changed. Last year former President Bill Clinton wanted a success to justify deploying an anti-missile system. The failure led him to postpone the decision. However, new President George W. Bush did not wait for the results; he is strongly committed to deploying more ambitious missile defenses, which critics have dubbed “Son of Star Wars.” With the decision made, his administration is downplaying the test’s importance. In the planned test, a target will launch from Vandenberg Air Force Base in California, to be hunted down by an interceptor launched from Kwajalein Atoll, on the other side of the Pacific Ocean. The target simulates a nuclear warhead launched by a “rogue state.” The final stage of the interceptor, called a “kill vehicle,” is supposed to hit the target at 6.7 kilometres a second. “The impact alone will vaporize the target,” says a Pentagon statement. But only if the kill vehicle hits the target. Shooting down a warhead with a missile is like trying to hit a bullet with a bullet. The task is not impossible, but it requires extreme precision in tracking the target and guiding the interceptor. For most of the test, a new ground-based radar on Kwajalein will track the target, providing position updates to the interceptor. Control will shift to sensors on the interceptor for the critical last few seconds of guidance. Both space- and ground-based sensors also will monitor the two vehicles to track their performance. The initial trial of the system in 1999 did succeed in destroying a target, but two subsequent tests failed. In the most recent, in July 2000, the interceptor failed to separate from its booster stage. Missile defense advocates say that failure was not important because it did not involve the final booster, which is still in development. However, that critical component has fallen 18 months behind schedule, so the Saturday trial will use the same stand-in. The Pentagon hopes to begin tests of the new launcher later in 2001, but do not plan to use it for intercept tests until October 2001 at the earliest. Defense Secretary Donald Rumsfeld downplayed expectations before the launch, warning that tests of new systems rarely produce a clear success or failure. “Most often [it is] a situation where a variety of things work properly and a variety of things may not, and more information may be needed. I suspect that will very likely be the outcome,