Longer duration firings of the high-energy laser on board the U.S. Missile Defense Agency's Boeing 747 airborne laser (ABL) are getting underway following the completion of the "first light" initial firing milestone onboard the aircraft in a ground test on Sept. 7.

The test, conducted at Edwards Air Force Base, Calif., lasted only a "fraction of a second" says a spokesman for Northrop Grumman, the makers of the Chemical Oxygen Iodine Laser (COIL). But this was long enough to prove "the laser is ready to demonstrate power output sufficient to destroy a ballistic missile in flight," he adds.

The COIL test marked "Knowledge Point 6" for the ABL program and came after a series of activation tests that began late last year. The work paves the way for "Knowledge Point 7," which will involve firing the laser through the system's Lockheed Martin-developed beam control/fire control system and out of the nose-mounted turret. This is targeted for the end of the year and is a crucial milestone towards an airborne intercept test against a ballistic missile, which ABL prime contractor Boeing says remains "on track" for around August 2009.

The COIL laser test was conducted under simulated flight conditions with fuel being supplied by onboard chemical tanks, and the laser itself subject to "atmospheric conditions consistent with those at the altitude at which the aircraft will fly," Northrop Grumman says. The "first light" test involved firing the laser into an onboard metallic calorimeter, or "beam dump," which measures the power of the beam by measuring heat rise in the metal.

Ongoing tests will see power and duration increased "over a period of weeks" while the laser is fine tuned by adjustments to the balance of the chemicals in the fuel. On completion of these ground tests the laser will be connected to the beam fire-control system for the start of flight tests.

Photo: U.S. Missile Defense Agency