Global positioning system is our best navigation network, but this may change in five years

Where would we be without the global positioning system? In the late 1970s and early 1980s, the US and Soviet Union started sending satellites up to built a network — the GPS and GLONASS respectively — to give their military exceptionally accurate navigation capabilities. How GPS works Around 30 satellites in the GPS constellation circle the planet 20,000km overhead, each completing two orbits of the Earth in a day Each satellite broadcasts microwave signals containing information about its position and time towards Earth GPS receivers combine signals from several satellites in a process called trilateration to calculate its position on Earth Local global navigation satellite systems use geosynchronous satellites, which are in a fixed position above a specific location These local systems can provide accurate position information, even among tall buildings The GPS was purely a US military tool until 1983, when a Korean Air Lines flight from New York City to Seoul strayed into Soviet airspace. That's because in the decades since the US first sent GPS satellites into Earth orbit, other countries have sent up their own global navigation satellite systems, such as China's military-developed BeiDou system and Europe's Galileo, which is for civilian and commercial use. Accuracy is ace, but reliability is key To augment global navigation satellite systems, countries have built satellite-based augmentation systems, or SBASs, Geoscience Australia's John Dawson said.