The United States successfully used an airborne laser to destroy a mock ballistic missile Thursday, the "first directed-energy lethal-intercept demonstration against a liquid-fuel-boosting ballistic missile target from an airborne platform," according to the U.S. Missile Defense Agency.
"The revolutionary use of directed energy is very attractive for missile defense, with the potential to attack multiple targets at the speed of light, at a range of hundreds of kilometers and at a low cost per intercept attempt compared to current technologies," Reuters quoted the agency.
But history shows that the military has for a long time offered rosy pronouncements on missile defense. A closer look at that history suggests that this week's successful test of the airborne laser (ABL) – a laser weapon mounted on a modified 747 jet – is unlikely to meaningfully shore up the country's defense any time soon.
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Throughout most of the half-century of U.S. investment in missile defense, the focus has been on deploying missiles, either from land or sea, to intercept enemy missiles. First came the Nike-Zeus program, which envisioned launching nuclear missiles that would detonate high in the atmosphere near incoming Soviet missiles. The program was never technically feasible, though, since it could easily be fooled by countermeasures and decoys, and the nuclear explosions would create electromagnetic pulses that would render the system's radars useless.
Nike-Zeus was canceled in 1961, but it inspired other programs – Nike X, Sentinel, Safeguard – under which several installations were built throughout the country to protect U.S. nuclear missile launch cites. These were all shut down because of various technical problems and the political pressures brought on by a public that was understandably wary of detonating nuclear weapons overhead.
Ultimately, the U.S. strategy shifted from using nuclear missiles defensively to using conventional missiles that would simply collide with incoming enemy targets. In the 1980s the Army launched its Homing Overlay Experiment, which deployed in space a fanlike propulsive structure that would collide with an intercontinental ballistic missile and destroy it. After three unsuccessful tests, a fourth, in 1984, succeeded in bringing down a Minuteman missile.
A year earlier, President Reagan announced his space-based Strategic Defense Initiative, which was dubbed "Star Wars" by critics. Reagan wasn't interested in stopping a few incoming missiles, but a full-scale nuclear attack. More than $100 billion was poured into the initiative, which had little to show for itself by the time the Cold War ended in 1989. Under presidents George H.W. Bush and Bill Clinton, missile defense was scaled back and refocused on ground-based interceptors.
Today, the U.S. missile defense system remains focused on ground-based interceptors, using radars and anti-ballistic missiles at various spots around the globe, including at sea. There have been a few successful tests, but with technical caveats. For instance, after a September 2006 successful test, Lt. Gen. Trey Obering, director of the Missile Defense Agency, said it was "about as close as we can come to an end-to-end test of our long-range missile defense system." But the incoming test missile didn't deploy countermeasures that a real enemy missile is likely to do.
This week's test of the Boeing YAL-1 Airborne Laser was the culmination of a program the Air Force began in 1996. The ABL works by heating a missile's skin, weakening it enough to cause failure. The ABL can fire off multiple lasers – potentially 20 to 40 shots – and has the advantage, unlike missile-to-missile defense, of not destroying itself in the process.
But there are problems.
First, ABL was designed for intercepting short-range missiles in their boost phase, tracing the heat signal that accompanies a launch. To shoot down a long-range ICBM, ABLs likely would have to fly over hostile territory and get within 300 kilometers, given rockets' short boost times. Many scientists think that such boost-phase intercepts are unfeasible.
Despite this week's success, that appears to be the belief of the Obama administration as well. In April 2009, Defense Secretary Robert Gates canceled a planned second ABL jet.
"The ABL program has significant affordability and technology problems, and the program's proposed operational role is highly questionable," Gates said. (According to another Obama appointee, the ABL program is "eight years behind schedule and $4 billion over cost.")
This week's success, then, must be put in context. One test and one plane aren't about to save the country from nuclear attack – even if that plane were piloted by Luke Skywalker.