Galileo positioning system

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The Galileo positioning system is a proposed satellite navigation system, to be built by the European Union (EU) as an alternative to the Global Positioning System (which is controlled by the military of the United States) and the Russian GLONASS. The system should be operational by 2010, two years later than originally anticipated.

It is named after the Italian astronomer Galileo Galilei. The Galileo positioning system is not abbreviated to GPS; use of the acronym GPS, here and elsewhere, refers to the existing United States system.

Galileo is intended to provide:

  • Greater precision to all users than is currently available.
  • Improved coverage of satellite signals at higher latitudes, which northern regions such as Scandinavia will benefit from.
  • A positioning system on which European nations can rely even in times of war or political disagreement.

Contents

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History

The first stage of the Galileo program was agreed upon officially on May 26, 2003 by the European Union and the European Space Agency (ESA). In 1999 the different concepts (from Germany, France, Italy and The United Kingdom) for Galileo were compared and reduced to one by a joint team of engineers from all four countries. The system is intended primarily for civilian use, unlike the U.S. system, which is run by and primarily for the U.S. military. The U.S. reserves the right to limit the signal strength or accuracy of the GPS systems, or to shut down public GPS access completely, so that non-military users cannot use it in time of conflict. The precision of the signal available to non-military users was limited before 2000 (a process known as selective availability). The European system will not be subject to shutdown for military purposes (though it may still be jammed by anyone with the right equipment), will provide a significant improvement to the signal available from GPS, and will, upon completion, be available at its full precision to all users, both civil and military.

The European Commission had some difficulty trying to secure funding for the next stage of the Galileo project. European states were wary of investing the necessary funds at a time of economic difficulty, when national budgets were being threatened across Europe. Following the September 11, 2001 attacks, the United States Government wrote to the European Union opposing the project, arguing that it would end the ability of the U.S. to shut down GPS in times of military operations. On January 17, 2002 a spokesman for the project somberly stated that, as a result of U.S. pressure and economic difficulties, "Galileo is almost dead" [1]

A few months later, however, the situation changed dramatically. Partially in reaction to the pressure exerted by the U.S. Government, European Union member states decided it was important to have their own independent satellite-based positioning and timing infrastructure. All European Union member states became strongly in favour of the Galileo system in late 2002 and, as a result, the project actually became over-funded, which posed a completely new set of problems for the ESA, as a way had to be found to convince the Member States to reduce the funding.

The European Union and European Space Agency then agreed in March 2002 to fund the project, pending a review in 2003 (which was finalised on May 26, 2003). The starting cost for the period ending in 2005 is estimated at €1.1 billion. The required satellites—the planned number is 30—will be launched throughout the period 2006–2010 and the system will be up and running and under civilian control from 2010. The final cost is estimated at €3 billion, including the infrastructure on Earth, which is to be constructed in the years 2006 and 2007. At least two thirds of the cost will be invested by private companies and investors, the remaining costs are divided between the European Space Agency and the European Union. An encrypted higher bandwidth Commercial Service with improved accuracy will be available at an extra cost, while the base Open Service will be freely available to anyone with Galileo compatible receiver.

The European Union has agreed to switch to a range of frequencies known as Binary Offset Carrier 1.1 in June 2004, which will allow both European and American forces to block each other's signals in the battlefield without disabling the entire system.

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International involvement

In September 2003, the People's Republic of China joined the Galileo project. China will invest €230 million (USD296 million, GBP160 million) in the project over the next few years (see external link, below).

In July 2004, Israel signed an agreement with the EU to become a partner in the Galileo project<ref>Press release</ref>.

On 3 June 2005 the EU and Ukraine initialled an agreement for Ukraine to join the project, as noted in a press release<ref>Press release </ref>.

On September 7 2005, India signed an agreement to take part in the project and to establish a regional augmentation system based on the European Geostationary Navigation Overlay System (EGNOS).

As of November 2005, Morocco and Saudi Arabia have also joined the program.

On January 12 2006 South Korea joined the program.

There is speculation that other countries might join the Galileo project, including Argentina, Australia, Brazil, Canada, Chile, Japan, Malaysia, Mexico, Norway, Pakistan and Russia. <ref>http://nww1.com/news/2004/0714israesigns.html http://www.siliconvalley.com</ref>.

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Political implications of Galileo project

As well as being an impressive technological achievement and a hugely practical tool, Galileo will be a political statement of European independence from the United States and its GPS system. A strong motivator for an independent system is that, though GPS is now widely used worldwide for civilian applications, it is a military system, which as recently as 2000 had selective availability that may be enabled in particular areas of coverage during times of war. Galileo's proponents argue that civil infrastructure, including aeroplane navigation and landing, should not rely solely upon GPS.

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System description

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Galileo satellites

  • 30 spacecraft
  • orbital altitude: 23222 km (MEO)
  • 3 orbital planes, 56° inclination (9 operational satellites and one active spare per orbital plane)
  • satellite lifetime: >12 years
  • satellite mass: 675 kg
  • satellite body dimensions: 2.7 m x 1.2 m x 1.1 m
  • span of solar arrays: 18.7 m
  • power of solar arrays: 1500 W (end of life)
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Services

There will be four different navigation services available:

  • The Open Service (OS) will be free for anyone to access. The OS signals will be broadcast in two bands, at 1164–1214 MHz and at 1563–1591 MHz. Receivers will achieve an accuracy of <4 m horizontally and <8 m vertically if they use both OS bands. Receivers that use only a single band will still achieve <15 m horizontally and <35 m vertically, comparable to what the civilian GPS C/A service provides today. It is expected that most future mass market receivers, such as automotive navigation systems, will process both the GPS C/A and the Galileo OS signals, for maximum coverage.
  • The encrypted Commercial Service (CS) will be available for a fee and will offer an accuracy of better than 1 m. The CS can also be complemented by ground stations to bring the accuracy down to less than 10 cm. This signal will be broadcast in three frequency bands, the two used for the OS signals, as well as at 1260–1300 MHz.
  • The encrypted Public Regulated Service (PRS) and Safety of Life Service (SoL) will both provide an accuracy comparable to the Open Service. Their main aim is robustness against jamming and the reliable detection of problems within 10 seconds. They will be targeted at security authorities (police, military, etc.) and safety-critical transport applications (air-traffic control, automated aircraft landing, etc.), respectively.

In addition, the Galileo satellites will be able to detect and report signals from COSPAS-SARSAT search-and-rescue beacons in the 406.0–406.1 MHz band, which makes them a part of the Global Maritime Distress Safety System.

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Galileo Satellite Test Beds

The European Space Agency and Galileo Joint Undertaking successfully launched the first of two Galileo In-Orbit Validation Element test satellites, GIOVE-A (GSTB/V2A), on 28 December 2005 by Soyuz launch vehicle, 05:19 UTC from Baikonur, Kazakhstan. It began transmitting as planned at 09:01 UTC while circling Earth at a height of 23 222 km. GIOVE-A, built by Surrey Satellite Technology Ltd (SSTL), carries two rubidium atomic clocks, two independently-developed Galileo signal generation chains and equipment to characterise the medium earth orbit (MEO) radiation environment. GIOVE-A is the first spacecraft to use a variant of the company's new GMP MEO and geostationary orbit (GEO) satellite bus.

The first navigational signals from GIOVE-A were received at Chilbolton Observatory in Hampshire, UK and the ESA Station at Redu, Belgium on 12 January 2006. Teams from SSTL and ESA have measured the signal generated by GIOVE-A to ensure it meets the frequency-filing requirements of the International Telecommunication Union (ITU), a process that was required to be complete by June of 2006.

GIOVE-B, built by Galileo Industries, has a slightly more advanced payload which also includes two atomic clocks and is targeted for launch in the autumn of 2006. GIOVE-B also has clock and MEO environment characterisation objectives, as well as Signal-In-Space and receiver experiments. GIOVE-B will also contain a rubidium atomic clock and additionally the first space-qualified passive hydrogen maser atomic clock.

These two Galileo testbed satellites will be followed by four in-orbit validation (IOV) Galileo satellites that will be much closer to the final satellite design.

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EGNOS

The European geostationary navigation overlay system is a system of satellites and ground stations designed to increase the accuracy of the current GPS and GLONASS in Europe.

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See also

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External links


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Press coverage

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References

<references/>

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