The idea of a computer navigating you to your destination was once the stuff of science fiction. The Global Positioning System (GPS) has changed all that, and it is now possible for drivers to get to any destination without the help of a map.
In a car equipped with GPS, all you need to do is input the address of your destination and the computer system instructs you when to make their next turn, directing you throughout the whole journey.
Not so long ago, only the aviation industry, the navy and the military had sophisticated navigation systems. But GPS is now available to everyone. Mobile phones can be equipped with GPS, allowing you to find the nearest restaurant or allowing parents to track where their children are.
GPS is the fruit of space technology first developed by the United States government in 1970s. A group of around 30 satellites send signals to GPS receivers.
First designed exclusively for military use, it was later made available for civilian use after a Korean Air passenger jet deviated from its path. Intruding on the Soviet Union's air space, it was shot down by a Soviet Union missile, killing all 269 passengers and crew - including 14 Hong Kong citizens.
GPS has played a key role in modern warfare since the first Gulf War. It helps soldiers and pilots to operate in hostile environments like deserts. It also helps guide missile attacks. It guides the missiles directly to their targets while minimising collateral damage to civilians.
GPS is so far the only satellite navigation system in the world. However, it is solely controlled and operated by the US government, which has the right to shut down the entire system in the event of a national emergency, reserving it for military use only. In fact, during the Kosovo war in the late 1990s, the Pentagon was accused of having downgraded the quality of GPS for civilian use. Commercial pilots reported their GPS devices did not function, trucks steered far from their destinations and scuba diving outfits reported it was getting impossible to locate dive sites.
