European rival to US Global Positioning System enters key phase
PARIS, Dec 7 (AFP) - 18:19 GMT - Plans to build a European rival to the United States' Global Positioning System (GPS), which enables planes, ships, cars, hikers and cruise missiles to navigate by satellite signals, enter a key stage this week.
The European Space Agency and the European Commission, the executive of the European Union, were to sign 80 million euros' (dollars') worth of contracts to take the scheme into the so-called definition phase, ESA said in a press release Tuesday.
Industrial firms will be given a year to flesh out the main details of the 2.7 billion euro (dollar) programme, such as how many satellites will be needed, where to deploy them and how they will work with ground stations, it said.
The system, called Galileo, is scheduled to start operations in 2005 and become fully operational in 2008.
GPS, launched and maintained by the US military, has revolutionised navigation.
It comprises 24 satellites in orbit 19,500 kms (11,000 miles) above the Earth that send down radio signals at extremely precise intervals, thanks to atomic clocks on board.
By knowing the position of each satellite and by calculating the slight difference in time it takes to receive their various signals, it is possible to pinpoint to within a few metres (yards) exactly where the person, plane or missile is.
At least three satellites are need to do this triangulation, which explains why a large number is needed to provide global coverage.
GPS receivers are now installed in top-of-the-range cars to provide road maps and street layouts. Miniaturisation of the devices is such that they have also been incorporated into devices as small as laptop computers and wristwatches.
ESA said it signed Tuesday a 20-million-euro contract with a 50-company consortium led by Italy's Alenia Aerospazio to come up with the basic concept for a satellite constellation and its ground systems.
"Current projections envisage that the Galileo system will consist of at least 21 satellites in medium earth orbit at 24,000 kilometers (15,000 miles), possibly complemented by geostationary satellites at 36,000 kms (22,500 miles), and the associated ground infrastructure," ESA said.
Later this week, the European Commission will sign four contracts, with 60 companies led by France's Alcatel Space, to draw up the system's specifications, ESA spokesman Franco Bonacina told AFP.
Galileo will be compatible with the US system, ESA says.