The controversial missile-defence shield being developed by the US will not officially go live in 2004, as originally intended by the Bush administration.
Military officials announced the delay on Friday, two days after a prototype interceptor failed to launch during a test. Critics accuse the US government of rushing the system through development without adequate validation.
The Bush administration had hoped to activate the first missile interceptors at bases in Alaska by the end of 2004. A spokesman for the US military鈥檚 Northern Command said it will now not happen until sometime in 2005, but claimed the failed test was not responsible for the delay. He said that military commanders are still evaluating many of the system鈥檚 various components.
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During Wednesday鈥檚 test, an 鈥渦nknown anomaly鈥� caused the experimental interceptor to shut down automatically before launch from the Ronald Reagan Test Site on Kwajalein Atoll in the Pacific Ocean. Its intended target, a ballistic missile launched 16 minutes earlier from the Kodiak Island in Alaska, crashed safely into the Pacific.
Each interceptor consists of a rocket with a 鈥渒ill vehicle鈥� that should detach in flight and zoom in on a target at high velocity. The failed test would have been the first to include a fully functional kill vehicle instead of a prototype.
Complex network
The missile defence system will consist of a network of interceptors linked to satellites and ground-based radars. The US military hope it will detect and destroy ballistic missiles launched against the US or Canada.
But critics have long claimed the system is far from ready, and say the latest developments show little has changed. 鈥淭he latest failure indicates that they still need to do a lot more testing,鈥� says Charles D Ferguson of the Council on Foreign Relations, a think-tank based in Washington DC, US.
Ferguson says a key challenge is integrating such a complex network. 鈥淭rying to get the radar and command and control integrated with the interceptors is very difficult,鈥� he told New Scientist. A small change in one place can lead to a large effect in another, he says, and 鈥渋t can be hard to control all those variables鈥�.
In five out of eight previous tests interceptors have successfully hit their targets. However, opponents claim these tests have been too simple to prove the interceptors will work in a real attack. The most recent test prior to Wednesday鈥檚 failure, in December 2002, also failed when the kill vehicle refused to detach from the rocket.
