WHITE SANDS MISSILE RANGE, N.M. (AP) -- An expensive experimental antimissile missile did today what it had been unable to do on six previous attempts -- hit a flying target.

A white puff of smoke in the southern New Mexico sky marked where the Army's Theater High-Altitude Area Defense, or THAAD, missile struck a target missile, which left a squiggly white trail of vapor just to the west.

Before today, the $3.9 billion system had missed its target on six consecutive attempts.

"I think I can put it in four letters -- B-A-N-G," said Bob Hunt, spokesman for the Army's program executive office for air and missile defense in Huntsville, Ala., where the THAAD program is managed.

"I got a voice mail message from White Sands, and there was a lot of ecstatic noise in the background," he said.

The test was to have taken place Tuesday, but a power failure the previous night at the Army's restricted missile range in southern New Mexico caused a postponement until today.

Today's test was originally scheduled for May 25, but was canceled after officials discovered a problem with the flying target it was supposed to hit. The Army then rescheduled the test for Tuesday morning, but that test was postponed because of a power outage at the White Sands Missile Range.

THAAD is supposed to shield American troops in the field by intercepting and destroying enemy missiles from ranges of 800 miles away or more. Supporters say its technology is working fine and blame the problems on the weapon's prime contractor, Lockheed Martin. Critics say it's too expensive and unreliable.

Lockheed was fined $15 million after THAAD's sixth failure to hit its target on March 29. If THAAD cannot make a second successful intercept by July 16, in addition today's test, Lockheed will owe an extra $20 million in penalties. The previous deadline, the end of June, was extended because of the May 25 problem with the target missile.