For the first time, after a decade of development, the U.S. Air Force fired its ALT (Airborne Laser Testbed) laser while in flight and hit a rapidly (1,800 meters a second) rising ballistic missile. The laser beam took several seconds to weaken the missile structure, and cause it to come apart. This test came only eight months after the smaller Advanced Tactical Laser (ATL) was fired in flight for the first time. The target was some lumber on the ground, which was hit. The ATL weapon was carried in a C-130H four engine transport.
Five years ago, manufacturers of combat lasers believed these weapons were only a few years away from battlefield use. To that end, Northrop-Grumman set up a new division to develop and build battle lasers. This optimism was caused by two successful tests six years ago. In one, a solid state laser shot down a mortar round. In another, a much more powerful chemical laser, hit a missile type target. Neither of these tests led to any useable weapons, and the combat laser remains the "weapon of the future."
Solid state lasers have been around since the 1950s, and chemical lasers first appeared in the 1970s. The chemical laser has the advantage of using a chemical reaction to create the megawatt level of energy for a laser that can penetrate the body of a ballistic missile that is still rising in the air hundreds of kilometers away. The chemical reaction uses atomized liquid hydrogen peroxide and potassium hydroxide and chlorine gas to form an ionized form of oxygen known as singlet delta oxygen (SDO). This, in turn is rapidly mixed with molecular iodine gas to form ionized iodine gas. At that point, the ionized iodine gas rapidly returns to its resting state, and while doing so releases photons pulsing at the right frequency to create the laser light. These photons are channeled by mirrors and sent on their way to the target (which is being tracked and pinpointed by other lasers). The airborne laser weighs about six tons. It can be carried in a C-130H, producing a laser powerful enough to hit airborne or ground targets fifteen kilometers away. The laser exists via a targeting turret under the nose of the aircraft. The laser beam is invisible to the human eye. The chemicals are mixed at high speeds, and the byproducts are harmless heat, potassium salt, water, and oxygen. A similar laser, flying in a larger aircraft (B-747) is to have enough range to knock down ballistic missiles as they take off. This is what was used in the recent test.
Nearly half a century of engineering work has produced thousands of improvements, and a few breakthroughs, in making the lasers more powerful, accurate and lethal. More efficient energy storage has made it possible to use lighter, shorter range ground based lasers effective against smaller targets like mortar shells and short-range rockets. Northrops' move was an indication that the company felt confident enough to gamble its own money, instead of what they get for government research contracts, to produce useful laser weapons. A larger high energy airborne laser would not only be useful against ballistic missiles. Enemy aircraft and space satellites would also be at risk. But companies like Northrop and Boeing are still trying to produce ground and airborne lasers that can successfully operate under combat conditions. The big problem with anti-missile airborne lasers is the power supply. Lots of chemicals are needed to generate sufficient power for a laser that can reach out for hundreds of kilometers and do sufficient damage to a ballistic missile. To be effective, the airborne laser needs sufficient power to get off several shots. So far, no one has been able to produce such a weapon. That's why these lasers remain "the weapon of the future," and will probably remain so for a while.