Today, ESA awarded a contract to Surrey Satellite Technology Limited (UK) for initial activities leading to the construction of a second spacecraft for the Galileo satellite navigation system. Named GIOVE-A2, the new satellite (estimated total value 25 to 30 million Euros) will be based on the company’s proven GIOVE-A technology. From now on, there will always be a European navigation satellite in space.
ESA wishes to guarantee the continuity of the Galileo programme with the permanent presence of a spacecraft in orbit. This will maintain European rights to the frequencies and allow continuation of the experiments initiated with the successful GIOVE-A mission and planned for the upcoming GIOVE-B satellite.
GIOVE-A2 will help maintain the critical International Telecommunications Union (ITU) frequency filing secured by its predecessor for a further 27 months and facilitate further development of ground equipment.
Monitoring of the space environment will also be an important ongoing mission objective for the new satellite. GIOVE-A was the first European satellite to be launched into medium Earth orbit (MEO) and it carries two environmental monitors. These units have been operated almost continuously since launch and are gathering vital data about the Galileo orbit environment that will help in the design of the full constellation.
The new satellite will incorporate some enhancements over GIOVE-A which will allow additional signals to be generated and received on the ground. The aim will be to provide early in-orbit experimentation with the common baseline L1 open service signals recently recommended by the European Union and the United States. In the future, these open service signals will provide free of charge position and timing competitive with other GNSS systems.
GIOVE-A was designed to broadcast Galileo signals from space so that Europe could claim the frequencies filed with the ITU for Galileo. Following a rapid development programme that started in the second half of 2003, the satellite was designed, built, tested and launched before the end of 2005. At 17:25 GMT on the 12 January 2006, the first Galileo signals were transmitted from the satellite. In March, ESA was able to confirm that it had brought the Galileo-related frequency filings into use, three months ahead of the official ITU deadline.
In addition to the frequency filing activity, GIOVE-A was required to broadcast navigation signals that have allowed testing of Galileo ground equipment during its continuing 27 month mission. This is an essential activity to encourage uptake of Galileo in the user communities.
GIOVE-A has also assisted ESA’s clock characterisation experiments. A highly accurate model was built from tracking the position of GIOVE-A which enabled ESA to test the performance of the satellite’s state-of-the-art onboard rubidium atomic frequency clock. Initial results demonstrated the clocks to be highly accurate, proving technology that will be integral to all future Galileo satellites including GIOVE-A2.
In charge of the development and validation of the Galileo system, ESA has to ensure that the programme is not endangered by the loss of the frequencies allocated to Galileo by the ITU in the event of a malfunction of the currently operational GIOVE-A or its successor GIOVE-B – planned for launch at end of this year. ITU regulations stipulate that frequency rights may be retained during a service interruption of no longer than two years.
The GIOVE-A2 satellite will be ready for launch in the second half of 2008. The actual launch date of this new satellite will be decided later, taking into account the situation of GIOVE-A and GIOVE-B.
GIOVE (Galileo In-Orbit validation Element) is the first step for the Galileo system. Preparations will be continued with the In-Orbit Validation phase comprising four satellites and the associated ground infrastructure, before the deployment of the 26 remaining satellites to achieve the full operational capacity.
Galileo is a joint initiative between ESA and the European Commission. When fully deployed in 2011-2012, it will be the first completely civilian positioning system.
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