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Missile Defense

Technology has always found its greatest consumer in a nation's war and defense efforts. Since the last attempts at a "Star Wars" defense system, has technology changed considerably enough to make the latest Missile Defense initiatives more successful? Can such an application of science be successful? Is a militarized space inevitable, necessary or impossible?

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lchic - 10:23am Oct 23, 2003 EST (# 15469 of 15471)
ultimately TRUTH outs : TRUTH has to be morally forcing : build on TRUTH it's a strong foundation

'' A future generation of anti-aircraft missiles could be made far harder to dodge by a guidance system inspired by the flight of dragonflies and hoverflies. The missiles will mimic a strategy called motion camouflage, which predatory insects use to trick prey into thinking they are stationary.

Insects that use this technique sneak up on their prey in a way that makes them seem stationary even though they are in fact moving closer. They do this by keeping themselves positioned between a fixed point in the landscape and their prey.

It has long been suspected that male dragonflies and other flying insects use this technique during aerial battles, and this has recently been confirmed (New Scientist print edition, 7 June).

Hitting the target

Akiko Mizutani and Mandayam Srinivasan of the Australian National University in Canberra used two video cameras to track duelling dragonflies and worked out the trajectories they used on attack runs. They found that they do indeed adjust their flight paths to appear stationary.

And now, biologists Andrew Anderson and Peter McOwan at Queen Mary College, University of London, have shown that humans can fall for the same trick (Biology Letters, DOI: 10.1098/rsbl.2003.0030).

War game

They tested this idea by programming missiles in a computer war game to follow the motion camouflage strategy. Players then had to try and shoot down missiles aimed at them before they themselves were hit.

Anderson and McOwan compared the performance of motion camouflage missiles with intercept missiles - that anticipated where a target aircraft would be and aimed for that spot - and heat-seeking missiles (see diagram). They found that the camouflaged missiles were able to get much closer to the target than the others before being shot.

The remarkable thing, says Anderson, is that these complex trajectories can be worked out by a neural network computer program based only on the movement of the target as seen from the viewpoint of the missile. There is no need for sensors to keep track of the fixed spot. "You can train a system to estimate its relative position without giving it 360-degree vision," says Anderson.

The researchers trained their neural network by feeding it data extracted from a video of hoverflies chasing their prey. In successive runs, the program was adjusted to make it better and better at following the correct path. "It's basically a tuning process," says McOwan.

One behind the other

Eventually, the network was able to guide the attacking missile based only on the relative movement of the target. "Once the network is trained it knows what it's doing," he adds.

The motion camouflage should work particularly well when used by several missiles simultaneously, according to Anderson. "If you put multiple missiles behind one another on the same motion camouflage trajectory, only the very first missile would be picked up by radar or infrared." The target would never know how many missiles were behind the first one.

The technology could also be used to outfox heat-sensors. A missile could detach and explode its rear stage a small distance from the target, creating a backdrop of infrared radiation. Then the rest of the missile would continue on a motion camouflage trajectory against this noisy backdrop, making heat sensors effectively blind to it. "It'd be like coming out of the Sun," says Anderson.

McOwan says that the British Ministry of Defence has expressed an interest in the technology. It might also be used in computer games. "Game makers might be interested in it as a strategy to allow software agents to sneak up on players," he suggests.

Duncan Graham-Rowe

http://www.newscientist.com/news/news.jsp?id=ns99993870

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