From space to a place on the map
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.
In an attempt to break the US dominance of global satellite navigation, other countries have developed their own. Russia operates a similar system, Glonass, which now comprises 16 functioning satellites, and is expected to cover the globe by next year.
The European Union is also building its Euro3.4 billion (HK$33.3 billion) Galileo project as a reliable alternative to American's GPS. The EU claims that unlike GPS, Galileo will be an independent system and for civilian use only. It is hoped to be fully functional by 2013.
Meanwhile, in Asia, Japan is developing a Quasi Zenith Satellite System, which provides accurate satellite positioning all over Japan. The Indian Regional Navigational Satellite System (IRNSS) was announced in 2006 and hoped to be ready in 2012.
China is also testing the waters of satellite navigation. Apart from investing Euro200 million in the EU's Galileo system, the mainland is expanding its Compass Navigation Satellite System, or Beidou Navigation Satellite, which currently covers part of China.
The US has voiced concern about the spread of navigation systems, fearing the technology could end up in the hand of terrorists. But for the hiker in Borneo, or for the sailor lost out in pacific, there is comfort in the thought that there will soon be various systems to rely on.
How might GPS be used in a wrong way?
Would GPS be safer if it were controlled by just one country?