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Sunday 20 Aug 2017 | 00:02 | SYDNEY

Bullseye on satellite

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21 February 2008 15:07

The Pentagon has confirmed that it has destroyed its malfunctioning spy satellite with an interceptor missile (one that is actually designed to shoot down other missiles). As I said in my opinion piece in The Australian on Tuesday, this result has upsides and downsides for the US and Australia. 

The Pentagon says they won't know for perhaps 24 hours whether the fuel tank, carrying toxic chemicals, was ruptured during the intercept. This raises an under-appreciated technical challenge related to missile defence. It's hard enough to 'hit a bullet with a bullet', as missile defence is often characterised. But how do you know you've scored a hit?

In the case of this satellite, the US can afford to wait 24 hours for confirmation, but in a combat situation there may be just minutes for commanders to make decisions about whether to launch more interceptor missiles in case their first salvo missed. America and its allies have relatively few missile defence interceptors in their arsenals, so  resources need to be used sparingly. And that's why China's protestations about American, Japanese and Taiwanese missile defences in the Pacific should not be taken too seriously, because China, with its 600-800 missiles, could easily overwhelm them.

Missile defence is useful against North Korea's smaller arsenal, but until it gets a lot cheaper, China has less to worry about.