Europe is building its own satellite-navigation system called Galileo. BBC News looks at why such a network is deemed necessary when we already have the US Global Positioning System (GPS).
What is Galileo?
Galileo will be a global network of 30 satellites providing precise timing and location information to users on the ground and in the air. It is costing some 3.4bn euros (£2.3bn; $4bn) of public and private investment and represents the biggest space project yet undertaken in Europe.
Galileo's first demonstrator spacecraft is being launched on 28 December; a second platform will follow in the New Year. They will trial the in-orbit technologies needed to run the system. These include atomic clocks, the heart of any global positioning system.
If all goes according to plan, a full constellation of Galileo satellites will be in operation by the end of 2010.
Why does Europe want Galileo?
On an important level, Galileo is a political project.
Like Airbus and the Ariane rocket programme, the new sat-nav system will assert Europe's independence. It will give EU countries guaranteed access to a service that is currently provided by a foreign (US) power.
GPS is a military-run programme; its signals can be degraded or switched off. Yes, the service is free, but its continuity and quality come with no guarantees - which means it cannot be relied upon, certainly not for safety-of-life applications such as landing planes and controlling trains.
Galileo will be a civil system. It will be run by a private consortium and will offer guaranteed levels of service.
How will Galileo differ from GPS?
As brilliant as GPS is, its accuracy and availability can on occasions leave a lot to be desired, as anyone who has a receiver will know. Sometimes it can be very difficult to get a fix and the accuracy can drift out to 10m or more.
The new Galileo system will offer five service levels (see below) and bring a step-change in performance. Since the first GPS satellite was launched in the late 1970s, sat-nav technology has evolved enormously.
Galileo should offer greater accuracy - down to a metre and less; greater penetration - in urban centres, inside buildings, and under trees; and a faster fix.
The Galileo system will also come with an "integrity" component - it will be able to tell users if there are major errors that could compromise performance.
Users will also benefit enormously from the agreement between Europe and the US to make their sat-nav systems compatible and "interoperable". That is, future receivers will be able to get a fix using satellites from either constellation.
And when the US introduces the next generation of GPS, users will see a further jump in performance.
What will Galileo be used for?
The central component of sat-nav is precise timing. The atomic clocks flown on the spacecraft keep near-perfect time, equivalent to the theoretical loss of one second over several thousand years.
This precision timing already plays a fundamental but often neglected role not just in navigation, but also in electricity distribution, the functioning of email and the internet, and in the security of financial transactions.
Galileo's improved clocks - their precision is 10 times better than current space-qualified clocks - will deepen and extend this role.
The better penetration, accuracy and guarantees of service should also give many more entrepreneurs the confidence to build business plans around sat-nav.
With sat-nav capability increasingly incorporated into mobile devices, there is likely to be an explosion in new applications. Many of these will be quite novel and unexpected uses for sat-nav.
Nonetheless, the transport sector will obviously be a big beneficiary. Industry will derive major efficiency gains through better management of supply chains and haulage fleets.
Galileo will deliver the tools national governments need to introduce wide-scale road charging.
Galileo will also underpin Europe's new air-traffic control system. The single European sky initiative will overhaul current technologies used to keep planes at safe separations, and allow pilots to fly their own routes and altitudes.
Is Galileo worth the cost?
Europe's member states have had reservations about the cost from the outset - and, in particular, the uncertainties that exist about what the precise end cost will be.
This prompted one sceptic to dub Galileo the "common agricultural policy of the sky".
There is also debate about the true scale of the revenue opportunities available. Who will want to pay for Galileo-enhanced services and how much will they be prepared to pay?
GPS was built at considerable cost by the US taxpayer but the returns for the American economy mean that investment has been repaid many times over.
All of Europe's big aerospace companies have been attracted to the Galileo project because they believe similar, if not better, returns can be achieved with an improved system.
Analyst forecasts talk of more than 100,000 new jobs being created in Europe, with eventually billions of sat-nav users worldwide generating revenues that are in the order of tens of billions of euros each year.
in BBC News (o artigo é ilustrado)
What is Galileo?
Galileo will be a global network of 30 satellites providing precise timing and location information to users on the ground and in the air. It is costing some 3.4bn euros (£2.3bn; $4bn) of public and private investment and represents the biggest space project yet undertaken in Europe.
Galileo's first demonstrator spacecraft is being launched on 28 December; a second platform will follow in the New Year. They will trial the in-orbit technologies needed to run the system. These include atomic clocks, the heart of any global positioning system.
If all goes according to plan, a full constellation of Galileo satellites will be in operation by the end of 2010.
Why does Europe want Galileo?
On an important level, Galileo is a political project.
Like Airbus and the Ariane rocket programme, the new sat-nav system will assert Europe's independence. It will give EU countries guaranteed access to a service that is currently provided by a foreign (US) power.
GPS is a military-run programme; its signals can be degraded or switched off. Yes, the service is free, but its continuity and quality come with no guarantees - which means it cannot be relied upon, certainly not for safety-of-life applications such as landing planes and controlling trains.
Galileo will be a civil system. It will be run by a private consortium and will offer guaranteed levels of service.
How will Galileo differ from GPS?
As brilliant as GPS is, its accuracy and availability can on occasions leave a lot to be desired, as anyone who has a receiver will know. Sometimes it can be very difficult to get a fix and the accuracy can drift out to 10m or more.
The new Galileo system will offer five service levels (see below) and bring a step-change in performance. Since the first GPS satellite was launched in the late 1970s, sat-nav technology has evolved enormously.
Galileo should offer greater accuracy - down to a metre and less; greater penetration - in urban centres, inside buildings, and under trees; and a faster fix.
The Galileo system will also come with an "integrity" component - it will be able to tell users if there are major errors that could compromise performance.
Users will also benefit enormously from the agreement between Europe and the US to make their sat-nav systems compatible and "interoperable". That is, future receivers will be able to get a fix using satellites from either constellation.
And when the US introduces the next generation of GPS, users will see a further jump in performance.
What will Galileo be used for?
The central component of sat-nav is precise timing. The atomic clocks flown on the spacecraft keep near-perfect time, equivalent to the theoretical loss of one second over several thousand years.
This precision timing already plays a fundamental but often neglected role not just in navigation, but also in electricity distribution, the functioning of email and the internet, and in the security of financial transactions.
Galileo's improved clocks - their precision is 10 times better than current space-qualified clocks - will deepen and extend this role.
The better penetration, accuracy and guarantees of service should also give many more entrepreneurs the confidence to build business plans around sat-nav.
With sat-nav capability increasingly incorporated into mobile devices, there is likely to be an explosion in new applications. Many of these will be quite novel and unexpected uses for sat-nav.
Nonetheless, the transport sector will obviously be a big beneficiary. Industry will derive major efficiency gains through better management of supply chains and haulage fleets.
Galileo will deliver the tools national governments need to introduce wide-scale road charging.
Galileo will also underpin Europe's new air-traffic control system. The single European sky initiative will overhaul current technologies used to keep planes at safe separations, and allow pilots to fly their own routes and altitudes.
Is Galileo worth the cost?
Europe's member states have had reservations about the cost from the outset - and, in particular, the uncertainties that exist about what the precise end cost will be.
This prompted one sceptic to dub Galileo the "common agricultural policy of the sky".
There is also debate about the true scale of the revenue opportunities available. Who will want to pay for Galileo-enhanced services and how much will they be prepared to pay?
GPS was built at considerable cost by the US taxpayer but the returns for the American economy mean that investment has been repaid many times over.
All of Europe's big aerospace companies have been attracted to the Galileo project because they believe similar, if not better, returns can be achieved with an improved system.
Analyst forecasts talk of more than 100,000 new jobs being created in Europe, with eventually billions of sat-nav users worldwide generating revenues that are in the order of tens of billions of euros each year.
in BBC News (o artigo é ilustrado)
