Is there any way to defend against a ballistic missile?
来源：未知 作者：狄嚅 时间：2017-07-21 08:01:22
By Jeff Hecht IS THERE any way to stop a ballistic missile? It’s a question raised by a report criticising the US government’s missile interceptor plan for Europe. Ted Postol of the Massachusetts Institute of Technology and George Lewis of Cornell University analysed publicly released videos of tests of the Standard Missile 3 (SM-3), which the US plans to deploy on ships in the Black Sea. The SM-3 is a surface-to-air missile with extra power and sensors. Though its low weight gives it the flexibility to be launched at sea, the researchers reckon only one or two of the 10 tests destroyed a warhead. The analysis was published in the May issue of Arms Control Today. Blocking a ballistic missile is far from easy: it’s like hitting a bullet with a bullet. Such missiles coast through space before re-entering the atmosphere up to thousands of kilometres from their launch site. A missile is most vulnerable while its rocket is firing during launch, because it is easier for sensors to target. The George W. Bush administration ploughed billions into the Airborne Laser to target missiles during launch, but it fell short of the required range and was abandoned last year. President Barack Obama cancelled two other Bush-era interceptors. When the Kinetic Energy Interceptor’s mission was broadened from hitting launches to warheads in space, it became too large to use. The Multiple Kill Vehicle, to destroy both decoys and warheads, became too heavy. “Cutting those programs was to some extent a no-brainer,” says David Wright of the Union of Concerned Scientists. The only US missile defence now deployed is a network of ground-based interceptors in Alaska and California to hit a missile mid-flight. That technology was to be expanded to a system based in Poland, but Obama nixed the idea to focus on ship-based defence, which also aims to target missiles mid-flight. It cost less and fared better in early tests. The US Missile Defense Agency says Postol and Lewis’s analysis is flawed. Either way, the SM-3 may be the best of a bad lot. More on these topics: