By Marina Malenic

A chemical laser integrated into a Boeing [BA] 747 failed to shoot down a target missile for the second time in a row Thursday, the Missile Defense Agency said.

The agency conducted a planned exercise of the Airborne Laser Test Bed (ALTB) Thursday morning at the Point Mugu Naval Air Warfare Center-Weapons Division Sea Range off the central California coast. The objective was to destroy a solid-fuel, short-range ballistic missile in its boost phase.

“Preliminary indications are that the system acquired and tracked the plume (rocket exhaust) of the target, but never transitioned to active tracking,” said MDA spokesman Rick Lehner. “Therefore, the high energy lasing did not occur.”

Program officials plan to conduct an investigation to determine the cause of the transition failure, Lehner added. He said the intermittent performance of a valve within the laser system is being examined as one possible cause.

Boeing produces the airframe and is the project’s prime contractor, while Northrop Grumman [NOC] supplies the high-energy laser and Lockheed Martin [LMT] has been developing the beam- and fire-control systems.

The system is designed to focus a laser beam on a pressurized part of a boosting missile long enough to cause it to fail.

Defense Secretary Robert Gates scaled back the program into a research experiment last year. It had previously been called the Airborne Laser (ABL). The Pentagon requested $98.6 million for directed energy research, including ALTB, in FY ’11.

ABL successfully shot down a target missile in February in the first such test of a flying directed-energy weapon.