Mid-space missile test marks milestone for defence strategy

PUBLISHED : Wednesday, 13 January, 2010, 12:00am
UPDATED : Wednesday, 13 January, 2010, 12:00am

China's mid-space missile interception test may seem less fancy than when it knocked out an ageing satellite with a missile three years ago, but its practical implication and technological achievements are far greater.

The success shows China is gradually closing the military gap with the United States, thanks in part to the People's Liberation Army's ability to learn from mistakes at the Pentagon.

China is now the only nation after the US that has successfully intercepted a supersonic incoming missile outside the atmosphere - a feat that not only attests to its sophisticated missile technology but also demonstrating it has acquired complicated radar tracking systems.

In 2007, China shocked the world when it knocked out one of its ageing weather satellites with a missile, raising concerns that it may target the satellites of other countries.

But according to General Xu Guangyu , a retired officer at the PLA's General Staff Headquarters, the satellite test was low-tech compared with the experiment announced on Monday. Xu said the 2007 test was relatively straightforward, as the satellite's mass and orbit were already known, and it had no defence system. It was also unable to make any emergency manoeuvres.

Monday's test was anything but straightforward. The defence system had to identify the location and trajectory of the missile. Because of the speed of the warhead, the time for response including detection, aim and launch was a matter of minutes.

'Satellite interception is like shooting a beer bottle. Missile interception is like shooting ducks,' Xu said. 'Monday's announcement marked a milestone in China's active defence strategy. Mid-course missile interception requires superior technology and equipment. As China is becoming one of the most powerful countries in the world, the development is natural.'

There was suspicion that the test may have been a computer simulation, but the US Department of Defence confirmed detection of abnormal activities in space.

'We detected two geographically separated missile launch events with an exo-atmospheric collision also being observed by space-based sensors,' Major Maureen Schumann, a Pentagon spokeswoman, was quoted as saying by the Associated Press.

'We are requesting information from China regarding the purpose for conducting this interception as well as China's intentions and plans to pursue future types of intercepts.'

The race between China and the US to weaponise space is something akin to the tortoise and the hare. The US has a huge lead, but slowly and surely China is starting to catch up.

The cause of the Pentagon's recent slow progress is not complacency, but rather serious technical issues. More than US$100 billion has been invested in its ground-based mid-course defence (GMD) system, but last year new tests were cancelled because of delays.

According to unclassified military research papers, China has been closely monitoring and studying US technology for more than a decade, and the army, air force and navy each has a ballistic missile defence programme.

Piecing together information from intelligence networks, academic journals and even media reports, Chinese military researchers have discovered a number of flaws in the GMD system that should be avoided.

Colonel Wang Guoyu of the PLA's Luoyang -based electronic equipment testing centre wrote in a 2005 paper that the GMD system had a weakness in mid-course interception that the PLA should address.

According to the paper, the US space-based infrared satellites could not effectively tell the difference between a real missile and the decoys that it released. The decoys could be as small as a balloon coated with metallic paint or as large as a cloud of aluminium foil. The satellite's infrared sensors had technological limits and could not obtain enough information to distinguish between them.

As a result, the defence system has to rely mainly on ground-based radar stations to analyse the invading objects. This is a time-consuming process and sophisticated missiles can be hard to detect.

Xu said Monday's test did not mean that the construction of China's missile defence system was completed.

'In comparison with the US, we still have a lot of work to do,' he said. 'In particular, we need more better and more powerful early warning satellites. The missile defence system's base should not be on the ground, but in space.'

Shooting to kill

Ballistic missiles can be intercepted in three phases of their trajectory

Boost phase

Intercepting missile while rocket motors are firing, usually over launch territory

Advantages: bright, hot rocket exhaust makes detection and targeting easier; decoys cannot be used

Disadvantages: positioning interceptors difficult; short time for intercept (typically about 180 seconds)

Mid-course phase

Intercepting missile in space after rocket burns out

Advantages: extended intercept time (up to 20 minutes); large geographic defensive coverage

Disadvantages: requires large, heavy missiles, plus sophisticated radar augmented by space-based sensors

Terminal phase

Intercepting missile after re-enters atmosphere

Advantages: smaller, lighter intercepting missile and less-sophisticated radar required

Disadvantages: very short reaction time (less than 30 seconds); possible blanketing of target area with hazardous debris