Galileo workshop considers GIOVE satellite results

Monday 13 October 2008

The European Space Agency (ESA) is hosting a workshop today that will present the findings of the in orbit verification and early experimentation from the GIOVE-A and GIOVE-B satellites.

SSTL’s Galileo team, led by Elizabeth Rooney, is supporting the workshop and will be presented with an award in recognition of SSTL’s outstanding contribution to the success of the Galileo programme.

The GIOVE (Galileo In Orbit Validation Element) satellites serve several purposes - to secure and maintain the Galileo frequency filing with the ITU (International Telecommunications Union), to validate technologies to be used in the Galileo operational constellation, to monitor the environment in the Mid-Earth Orbit (MEO) and to generate Galileo signals so that user equipment can be developed. GIOVE-A was developed rapidly in a little over two years under a €28M contract placed by ESA in July 2003.

Almost 3 years after the successful launch of GIOVE-A, and 6-months after the launch of GIOVE-B, the workshop will focus on the health and recent in-orbit testing of the MBOC (multiplexed binary offset carrier), which is broadcast by the new satellite. The performance of the Passive Hydrogen Maser (PHM) clock onboard GIOVE-B, which promises increased accuracy and stability compared to the rubidium atomic clock used onboard GIOVE-A, will also be explored.

The first Galileo satellite, GIOVE-A, was launched in December 2005. Since securing the Galileo frequencies with the ITU in January 2006, GIOVE-A has consistently returned data from clock characterization experiments, radiation monitoring results as well as transmitting representative Galileo navigation signals. In addition to using the signals to confirm the improved performance of the binary offset carrier signals, ESA has used the navigation signals in their GIOVE Processing Centre (GPC) housed in ESTEC which computes precise orbits and clocks of the GIOVE satellites based on the measurements collected by a global network of Galileo Experimental Sensor Stations. The GPC generates the navigation data messages that are then uploaded to the GIOVE satellites. In the past year, SSTL has worked closely with ESA to upgrade the ground interfaces to support improved data update rates and also to introduce new fields in the navigation messages to improve interoperability with GPS.

Results from several in-orbit test campaigns performed on the GIOVE-A navigation signals have confirmed that the payload performance has remained consistent during the life of the mission. As GIOVE-A continues to provide excellence performance and availability, the satellite’s mission has been extended a further year beyond its nominal lifetime of 27 months in order to maintain continuity of Galileo’s in-orbit validation prior to the launch of GIOVE-B and beyond.

The results from the GIOVE satellites provide important information about the in-orbit performance of technologies for ESA and companies, including SSTL, that are currently bidding to build the operational Galileo satellites.

SSTL together with its German partner OHB-System ( was recently downselected by ESA and the European Commission (EC) as one of two potential suppliers of satellites to the Galileo operational system to be deployed by 2013.

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