In the Gulf War, Saddam Hussein's forces fired SCUD missiles at Israel and U.S. bases in the Middle East. The Patriot missile defense system was deployed to protect American interests. Patriot missiles can destroy incoming missiles on their downward path, but what if you could catch it earlier and destroy the missile during its boost phase (the upward path near its origin)? That's what the U.S. Air Force's Airborne Laser (ABL) is designed to do -- it's being developed by Boeing, Northrup Grumman and Lockheed Martin contractors.
The ABL is mounted in a modified Boeing 747 jumbo jet. It consists of four lasers, advanced adaptive optics, sensors, and computers to locate, track and destroy missiles. It works like this:
- Infrared sensors detect the heat signature of a boosting missile and report information to an Active Tracking Laser.
- The Active Tracking Laser tracks the missile and reports relevant tracking information (distance, speed, altitude).
- The Tracker Illuminator Laser scans the target and figures out where best to aim the high-energy laser.
- The Beacon Illuminator Laser shines on the target, determines the amount of atmospheric turbulence between the ABL and the target, and relays this information to the adaptive optics system in the aiming mechanism of the high-energy laser.
- The Adaptive Optics system is made of deformable mirrors that compensate for atmospheric turbulence. The turret mounted in the nose houses a 1.5-meter telescope as part of the optics system.
- The COIL laser fires a megawatt beam at the target. The beam exits the ABL through the nose-mounted turret.
- The high-energy laser beam penetrates the skin of the target missile and disables or explodes it, depending upon where the beam strikes.
All of the operations are coordinated by computer.
The Air Force is currently testing the ABL and says that its range is in the order of hundreds of kilometers. The ABL will require a crew of six when it is fully operational, and they'll wear special safety goggles to protect their eyes from possible reflections of the beams by water droplets in the air.
High-energy lasers like those developed for the ABL are being designed and developed for use on land and at sea. These lasers would be truck- or ship-mounted and capable of shooting down incoming missiles, artillery shells and possibly enemy aircraft.