WHEN the US air force began work on the Airborne Laser a decade ago (快猫短视频, 18 June 1994, p 4), it was aiming to build a weapon that could stop ballistic missile launches by 鈥渞ogue states鈥�. After 10 years and more than $2 billion spent, the project is still struggling to get anywhere.
It seemed at the time a far more realistic idea than the 鈥淪tar Wars鈥� programme proposed by Ronald Reagan a decade earlier. Reagan鈥檚 plan to make nuclear weapons 鈥渋mpotent and obsolete鈥� was a response to the cold war nuclear stand-off, in which thousands of US and Soviet nuclear weapons were poised for launch. As part of the programme, Reagan proposed to build a fleet of orbiting battle stations equipped with 5-megawatt lasers that would zap nuclear missiles as they rose out of the atmosphere.
Real-world technology fell far short. Each laser would have needed tonnes of chemical fuel for hundreds or thousands of shots, to be fired with split-second timing and deadly accuracy at moving targets thousands of kilometres away. Few specialists thought the laser weapons had any chance of working. Lasers simply aren鈥檛 very good at destroying things; bullets are more deadly than beams. But whether Star Wars was a brilliant bluff or a staggering blunder, the Soviet Union collapsed long before the Pentagon had to deliver any working hardware.
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The Airborne Laser had much more modest goals. It was a response to the perceived threat of the early 1990s 鈥� rogue states such as North Korea which might launch one or two intercontinental ballistic missiles at the US. The original idea was to arm a fleet of seven jumbo jets with lasers, so that in times of high political tension they could patrol the skies around such a rogue state, ready to fire on any missile seconds after launch.
Technically, it seemed feasible. Targets would be only a few hundred kilometres away. It is far easier to fly a hefty laser and its chemical fuel in a Boeing 747 than to send them into orbit, and you can make repairs. The new programme could also take advantage of a decade of steady improvements in laser technology. Veterans of the Star Wars programme who had lost faith in that ambitious project thought that the Airborne Laser had a realistic chance of working.
The problems began when it came to actually making and testing the hardware. Making the plumbing to handle the gas flowing through the lasers proved more complex and expensive than expected, and integrating the pieces into a working laser more difficult. Now the challenge is to fit six laser modules into a 747 and combine their output into a single powerful beam 鈥� a deadline originally set for February 2003. This has still not been achieved, and no new deadline has been announced. In May, the Congressional General Accounting Office described the prototype鈥檚 military usefulness as 鈥渉ighly uncertain鈥�, as the hardware hasn鈥檛 even been tested.
Now the Missile Defense Agency is quietly scaling back its ambitious plans. In February, it officially shifted the programme down a gear, vowing to demonstrate technological capabilities before charging ahead with building costly equipment. Sensibly, the agency also put aside plans to build the other six flying lasers until they can be sure that the prototype works.
Combining the laser beams isn鈥檛 their only problem. Even with a jumbo jet to haul it, the big laser鈥檚 weight remains an issue. Such a heavy piece of equipment might upset the plane鈥檚 balance. Perhaps the biggest technical risk is controlling and stabilising the laser, so that the aircraft鈥檚 vibration doesn鈥檛 spoil the aim.
Only if all those steps succeed and the plane gets off the ground could full tests begin. Whether they will be realistic tests is another matter. Given the record of missile defence testing, it鈥檚 a good bet that the military engineers will manage to find a soft target.
Meanwhile as schedules have slipped, budgets have soared. At the end of May, the Pentagon had to allocate another half a billion dollars, putting total spending so far at $2.6 billion, way beyond the original $1 billion budget. And future costs remain uncertain. The laser equipment requires special maintenance and fuel, while many aspects of the technology are still undeveloped. And of course there would then be the fleet of planes to buy and arm. Nobody has figured out how much this would cost.
On top of all that, there are serious questions about whether a working airborne laser has any real use. Launching an intercontinental ballistic missile is hardly a clever way to hurt the US, since it reveals where the attack comes from and would presumably subject that country to all the horrors of a retaliatory strike. There are far easier ways to deliver a nuclear warhead 鈥� launching a short-range missile from a ship, for example 鈥� which the airborne laser would be helpless to prevent.
A video game version would certainly be cheaper and easier. And maybe just as effective.