Interceptor Collides With Target, Fourth Hit for Missile Defense

Wade Boese

The Pentagon scored its third straight intercept of a mock warhead moving through space March 15, raising the record of the ground-based midcourse missile defense system to four hits in six attempts.

The latest test differed little from previous tests, except that the Pentagon included three decoy balloons with the target rather than just one. Prior to the test, Pentagon officials claimed that adding two more decoys to the target cluster would make the test more challenging for the missile defense system, which had its first intercept try—a hit—in October 1999.

As in earlier intercept tests, the Pentagon launched the target over the Pacific Ocean from Vandenberg Air Force Base in California. Approximately 20 minutes later, a missile interceptor was fired from Kwajalein Atoll in the Marshall Islands to attempt an intercept.

As the interceptor drew within roughly 2,250 kilometers of the mock warhead and decoys, the exoatmospheric kill vehicle (EKV), which seeks out the target using data from a ground-based radar and its own onboard sensors, separated from the interceptor booster. After approximately five minutes, the EKV struck and destroyed the target at a combined speed of nearly 26,000 kilometers per hour more than 225 kilometers above the Earth’s surface.

Because the Pentagon does not have a radar that can perform unassisted, early-flight tracking in the test area, the interceptor, when first launched, is shot toward a point in space determined from data gathered by a radar that is tracking a C-band transponder on the target. Once the EKV separates from the booster, it receives no information derived from the C-band transponder.

In the closing seconds before an intercept, the EKV relies on its infrared sensors, as well as preprogrammed information on the objects it is expected to see, to select the right target. Some critics object that the Pentagon is unlikely to have as much information on future enemy warheads and decoys as it does with its own test elements, but Pentagon officials defend the use of preprogrammed information, explaining that they hope to have such information in a future, real-world situation.

Trying to deflect any criticism of the Pentagon’s approach, Deputy Secretary of Defense Paul Wolfowitz told CNN a day after the test that, “before some critic discovers it, this was not a realistic test,” adding that the decoys were “not as good a decoy as we would expect to face later.” Wolfowitz stressed that the system is only a development program at this time.

The next intercept test employing the ground-based system is planned for June. The Pentagon has not determined how many decoys may be included in the next test because it is still in the process of completing the post-test analysis of the March 15 intercept.