China has apparently built a network of ground-based lasers that are able to disable or destroy low orbit space satellites. The first of these ground laser systems was spotted (by a retired Indian army officer who specializes in finding secret facilities) in northwest China (Xinjiang Province), 236 kilometers south of the provincial capital. The Indian officer is an expert satellite imagery analyst who, like many researchers, uses commercial satellite images to scour remote areas of China for secret facilities. This has become a popular, and revealing, activity for many amateurs. This use of talented amateurs and the Internet enables groups of experts to share finds and use their talents together to deduce what it is they have found. In the case of ground-based anti-satellite lasers, a lot of work on high-powered chemical lasers was done by the Americans over half a century to develop and test such weapons for ballistic missile defense. Many details of that work are public knowledge. By scrutinizing the Chinese ground facilities, and referring back to earlier work, it became apparent that the Chinese had used more accurate satellite tracking techniques (using more powerful computers and ground multiple ground-based sensors) to construct a system employing multiple ground-based lasers. Analysis of the Chinese Xinjiang facility indicated three ground-based lasers and a tracking facility were at the site discovered. By combining tracking data from other ground-based tracking facilities the orbit of a low orbit (under 500 kilometers) satellite coming into range could be calculated precisely. Then one or more of these ground lasers could fire simultaneously and disable or destroy the passing surveillance, radar or electronic monitoring satellite with multiple beams of laser energy hitting the satellite. Building several more of these facilities would increase the anti-satellite capabilities.
Most of the work on these types of chemical lasers was done by the United States but, after more than a decade of effort and billions of dollars to build a practical application, the U.S. Department of Defense halted work in 2011 on the air force ALT (Airborne Laser Testbed). This project was put into storage until such time as more effective technology was available to revive the effort, or it was decided that the ALT was not worth the storage expense. ATL cost over $5 billion during 16 years of efforts. It never worked, at least not in a practical sense. In 2010, for the second time in a row, the ALT failed in an attempt to use its laser to destroy a ballistic missile. That time the problem was with the radar and fire control system, which failed to lock the laser on the actual missile. The radar did detect the actual missile launch. In the past, the main problem had been a lack of power to drive the laser to lethal levels. Because of that, the ALT program has been an expensive near miss for nearly two decades.
In 2009 ALT had been demoted from a system in development to a research program. The reason for this was all about energy supply. Even if ALT worked flawlessly, it did not have enough energy to hit a launching missile from a safe (from enemy fire) distance. ALT needed more than twenty times as much energy than it then had and it will be a while before that problem is solved. China got around that by basing its chemical lasers on the ground and using an additional rare material (neodymium) that China is the largest source of. Actually, neodymium is common worldwide but it is one of those “rare earths” because few countries refine it. Neodymium is used to create high powered lasers and, in conjunction with the chemical energy systems, the Americans developed for their ALT the Chinese can, using this existing technology and their known resources, create ground-based lasers that have sufficient energy to damage or destroy low flying satellites.
There have been some successes with this kind of weapon. In 2010 the U.S. Navy successfully tested their laser weapon, using it to destroy a UAV. This was the seventh time the navy laser has destroyed a UAV this way. The laser cannon was mounted on a KINETO Tracking Mount, which is similar, but larger (and more accurate than) the mount used by the Phalanx CIWS (Close In Weapons System). The navy laser weapon test used the radar and tracking system of the CIWS. In 2009 CIWS was upgraded so that its sensors could detect speedboats, small aircraft, and naval mines. The problem here is that knocking down UAVs is not something that the navy needs help with, and the current laser gun technology has to be improved quite a bit before it's worth mounting on a ship.
In 2005 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 in 2004. 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". The basic problems are reliability and ammo (power to generate the laser).
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 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 fired at the target which is being tracked and pinpointed by other lasers. The airborne laser weighed 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 exits 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 based ALT) was supposed to have enough range to knock down ballistic missiles as they took off. But the ALT never developed sufficient range in atmosphere to be an effective weapon.
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. Northrop's 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 but 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 has always been 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.
China has apparently created a practical weapon by avoiding the factors that prevented American efforts from succeeding. By using multiple, more powerful ground-based chemical lasers it was possible to generate sufficient energy to damage or disable low flying satellites and high flying aircraft as well. In its current state the Chinese systems not capable of intercepting ICBM warheads but, rather than going after a difficult goal, the Chinese figured out what was worth zapping with existing laser technology. Sometimes success is mainly a matter of correctly matching goals with capabilities.