Laser guns have been a staple of science fiction for decades, but in reality their use is generally restricted to sighting, ranging and targeting applications. But that is all set to change. For the first time an airborne laser (ABL) weapon mounted aboard a modified Boeing 747 has shot down a ballistic missile launched from an at-sea mobile launch platform off the central California coast.

The February 11 test was the first directed energy lethal intercept demonstration against a liquid-fuel boosting ballistic missile target from an airborne platform. It serves as a proof-of-concept demonstration for directed energy technology for the Missile Defense Agency. The test comes less than a year after a similar test that located, tracked and fired on a target missile. In that test a surrogate high-energy laser was used. That surrogate has now been replaced by a megawatt-class high-energy laser.

The latest test involved launching a short-range threat-representative ballistic missile from an at-sea mobile launch platform. Within seconds, the Airborne Laser Testbed (ALTB) used onboard sensors to detect the boosting missile and used a low-energy laser to track the target. The ALTB then fired a second low-energy laser to measure and compensate for atmospheric disturbance. Finally, the ALTB fired its megawatt-class High Energy Laser, heating the boosting ballistic missile to critical structural failure. The entire engagement occurred within two minutes of the target missile launch, while its rocket motors were still thrusting.

Less than one hour later, a second solid fuel short-range missile was launched from a ground location on San Nicolas Island, Calif. and the ALTB successfully engaged the boosting target with its High Energy Laser, met all its test criteria, and terminated lasing prior to destroying the second target. The ALTB destroyed a solid fuel missile, identical to the second target, in flight on February 3, 2010.

The use of directed energy is very attractive for missile defense, with the potential to attack multiple targets at the speed of light, at a range of hundreds of kilometers, and at a low cost per intercept attempt compared to current technologies. It also means the strength of the laser can be altered to suit the circumstances.

However, even with the success of the demonstration, questions still remain as to the real-world worth of the system. The one to five minute period just after launch is the easiest time to track a missile because its exhaust is burning bright and hot. This means the intercepting laser must be in close proximity, as was the case with the successful test. Shooting down a long-range missile after that window is closed is going to be a much more difficult (and useful) feat. But we’re sure the Missile Defense Agency is working on it.

The high-energy laser was designed and built by Northrop Grumman Corp, while Lockheed Martin Corp supplied the beam- and fire-control systems and Boeing provided the aircraft, the battle management system and overall systems integration and testing.

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