An interceptor missile destroyed a mock warhead in space over the Pacific Ocean on Friday in a key test of the United States' missile defense system, a Missile Defense Agency spokesman said.
The 54-foot interceptor shot out of an underground silo at Vandenberg Air Force Base on the central California coast at 10:39 a.m., 17 minutes after a target missile was launched from Kodiak Island, Alaska, said agency spokesman Rick Lehner.
A refrigerator-sized "kill vehicle" separated from the interceptor. Moving at 18,000 mph, it struck a 4-foot-long mock warhead released by the other missile. Lehner said both disintegrated more than 100 miles above the Earth and a few hundred miles west of Vandenberg. The interceptor's flight lasted 13 minutes.
It was the most realistic test of the systems that would be used against a real attack, according to Lehner.
More than $100 billion has been spent on America's missile-defense system since 1983 and it has been the subject of criticism by those who call it a costly boondoggle. There also have been allegations that very early tests were rigged or their success exaggerated. The Pentagon says the technology used in those tests is not part of the current research program.
Critics also argued early on that the demise of the Soviet Union made a full-scale missile attack on the U.S. unlikely. Supporters say the U.S. still is vulnerable to missiles from rogue states.
In July, North Korea unsuccessfully test-fired a missile that was believed capable of reaching the northwestern U.S. coast.
On Monday, Defense Secretary Donald H. Rumsfeld visited Fort Greely in Alaska, where 11 interceptors are kept.
Asked whether the missile shield was ready for use against a North Korean missile, Rumsfeld said he would not be fully persuaded without more realistic testing.
"A full end-to-end" demonstration is needed "where we actually put all the pieces" of the highly complex and far-flung system together, he said.
There have been nine intercept tests since 1999, and five were successful in hitting the target, Lehner said.
Friday's test was not intended to be an intercept maneuver. It was designed to see if the kill vehicle could get close to the warhead to test the tracking and sensor systems which would be used in an actual missile attack — the kind of systems that Rumsfeld said needed more testing.
"It gave us a good chance to measure overall system performance. It was the most operationally realistic test we've had," Lehner said.
"The intercept was definitely a bonus," Lehner said. "It (the kill vehicle) obviously maneuvered itself into the proper position. We were hoping for a close approach."
An actual intercept test was scheduled for the end of this year or in early 2007, Lehner said.
The interceptor was launched by remote control from a command center in Colorado. The test also was the first use of an early warning radar at Beale Air Force Base, California, to provide the data required to put the interceptor on a proper path toward its target.
Data from the test will take several weeks to review, Lehner said.
The $85 million launch was postponed from Thursday after fog socked in Kodiak Island. There was also fog over Vandenberg Friday morning but it burned off.