Missile Defense Interceptor Hits Target, But Not All Perfect in Test

Wade Boese

More than a year after the last test of its proposed strategic missile defense system failed, the Pentagon succeeded July 14 in destroying a target warhead in space, though a key radar suffered a software glitch.

Marking the second hit in four attempts, the July 14 test involved launching a modified Minuteman II missile, carrying a mock warhead, from Vandenberg Air Force Base in California toward Hawaii.

Approximately 20 minutes after the Minuteman was launched, the Pentagon fired a ground-based interceptor carrying an exoatmospheric kill vehicle (EKV) from the Kwajalein Atoll in the Marshall Islands, more than 7,700 kilometers away. Roughly eight minutes later, the EKV, which is designed to seek out and collide with a target in space, hit the mock warhead some 220 kilometers above Earth with a closing speed of more than 26,000 kilometers per hour, destroying the target.

As in previous intercept tests, the Pentagon knew the target’s launch time and trajectory, which was plotted to avoid the more than 8,000 objects in orbit around Earth. The target was also outfitted with a C-band transponder, which sends out a signal precisely identifying the target’s location. Data from the transponder was used to formulate the initial intercept plan for launching the booster and EKV because there is no radar available in the test range to track the target early in its flight. However, after it separated from its booster at a distance of about 800 kilometers from the target, the EKV received no data from the transponder.

This latest test essentially repeated the same mission as last year’s July intercept attempt, except the Pentagon replaced the single, large balloon decoy that accompanies the mock warhead with a new one, which was more similar to the target than last year’s decoy but still markedly different. In last year’s test, the EKV did not separate from the booster, preventing an intercept from being attempted. (See ACT, July/August 2000.)

Because that test failed in its early stages, the Pentagon had no opportunity to determine whether the EKV could receive target updates after separating from its booster using data gathered by the prototype X-band radar located at the Kwajalein Atoll. This radar is tasked with tracking and helping to discriminate the target from any decoys. During this last successful intercept attempt, the EKV, which initially orients itself in space by checking its location against various stars, received two in-flight updates after separating from the booster that helped guide it to the target.

After arriving in the approximate area where the intercept was to take place, the EKV used its onboard infrared and visual sensors to seek out the target and discriminate between the target and decoy. The EKV was preprogrammed with information on both objects, including data that the target would be less bright than the decoy. A spokesperson for the Ballistic Missile Defense Organization (BMDO), which oversees U.S. missile defense programs, said that the Pentagon would “hopefully” have similar basic information available through U.S. intelligence in a real-world situation.

The scripting of the tests has raised concerns about their lack of realism. A Defense Department report from last August recommended that, in future operational testing, “rehearsed engagements with a priori knowledge of target complex, target trajectory, and time of launch need to be discontinued.” (See ACT, July/August 2001.) However, the Pentagon has stressed the need to increase the difficulty of the tests one step at a time.

BMDO initially reported that all system elements seemed to have worked as expected but later acknowledged that the prototype X-band radar had not immediately verified whether a hit had actually taken place. In a real attack, the Pentagon would need such information to know whether it should fire additional interceptors.

Noting that this test marked the first time the Pentagon had tried to use the radar to perform a kill assessment, the BMDO spokesperson described the problem as a “minor anomaly.” According to a spokesperson from Raytheon, the company heading the X-band radar program, the prototype radar continued to collect data that showed an intercept had occurred, but a software code problem prevented that information from being properly routed and reported at the time.

Reports originally suggested the radar had been overwhelmed by data after the intercept and could not process it, but the software problem actually occurred 64 seconds before the intercept took place. Major General Willie Nance, who heads the testing of the ground-based missile defense system, said August 9 that BMDO has already made the software fix.

The next intercept attempt using the ground-based interceptor system, which the Clinton administration named the national missile defense program and which the Bush administration now calls the ground-based midcourse element, will be in October, and another will be in February. The October test will be a repeat of this last test because BMDO wants to have more confidence that the system can perform its basic mission before making the tests more complicated.

A total of 20 additional intercept tests, four per year, using this system are currently planned through 2006, and the Pentagon aims to deploy in Alaska an initial, rudimentary system using about five missiles as early as 2004.

Each intercept test costs about $83 million, but BMDO Director Lieutenant General Ronald Kadish said the day before the test that he expects that figure to decrease over time. “The overall cost of the testing per unit is going to come down when we actually do more of them,” Kadish stated.