Laser Will Knock Down Enemy Missiles

American troops are in battle against some evil foreign power. The enemy is losing, and in an effort to redress the balance, launches a missile packed with chemical agent.

As the missile boosts from a hidden launcher, sensors in a modified Boeing 747 pick up the telltale signature of the launch. Immediately, the crew aboard the craft springs to action. Sensors and radars locate the missile, charge up a laser and fire. The missile explodes, American service members lives are spared, and all is well with the world.

But this is not the stuff of fiction. It is becoming reality and defense officials expect to test just such a system against a live missile Sept. 5, 2003. If all goes well, the program could become fully operational around 2007.

The Airborne Laser, designed to defend against the growing threat of theater ballistic missiles, is being built by a consortium of high-technology firms including Boeing, TRW and Lockheed-Martin. The project is expected to cost $1.1 billion, which includes the cost of two specially modified 747s. The Airborne Laser is intended to kill ballistic missiles in the boost phase at ranges of up to hundreds of miles.

The aircraft will be autonomous -- meaning it will detect, acquire and destroy enemy missiles with the equipment on board. "While we can take cues from outside the aircraft, it is designed to be used alone," said Paul D. Shennum, Boeing vice president for the Airborne Laser program.

A high-energy laser being developed by TRW is at the heart of the program. It is a chemical oxygen iodine laser and has already been tested at 110 percent of the power needed to knock out a rocket. Since the laser will be aboard a plane, TRW is using composite materials, plastics and titanium to reduce the weight.

Firing a laser through the atmosphere from a moving plane to knock out a missile traveling at ballistic speeds is an incredible feat of engineering. Air turbulence distorts lasers. So when firing, computers aboard the aircraft will take into consideration the distortion and focus on the target. The aircraft will have two illumination lasers that will acquire the target and give information on where the distortion in the air is so the main laser can adjust. Lockheed-Martin is building the illumination lasers.

Lockheed Martin is also building the beam control system and nose-mounted turret. The beam control system processes information on target acquisition and tracking and also handles compensating for atmospheric distortion. Planes bounce around in flight -- even something as large as a 747. The beam control system compensates for this. In the nose-mounted turret is a 1.5 meter telescope that focuses the beam.

The Airborne Laser program is just one part of the military's total theater missile defense system. Along with the Army's Patriot 3 system, the Navy's Area-wide defense system and the Army's Theater high-altitude area defense system, the program will help protect U.S. troops from the growing threat of theater ballistic missiles.