With 30 satellites in orbit, Galileo provides metre-level accuracy to billions of users worldwide. The ground segment, the most complex developed in Europe, includes two Control Centres, two Security Monitoring Centres, seven service entities, and a global network of uplink and sensor stations. These components generate the Galileo navigation message, maintain satellite timing, pinpoint positions, monitor drift, process data, and ensure constellation reliability.

The upgrade to System Build 2.0 was crucial for enhancing the system, particularly for the Public Regulated Service (PRS), which offers robust encrypted signals for authorized governmental users.

"How can we migrate such an extraordinarily complex system without its billions of users noticing?" wondered the ESA Ground Segment team. They developed a strategy ensuring continuous service through redundant infrastructure and the capability to roll back the migration within the first 48 hours if necessary.

Leading up to the upgrade, teams simulated various scenarios to validate procedures and train personnel. The migration from the legacy system to a new infrastructure, the largest ever for a navigation ground segment, took less than six weeks. Authorization to migrate was granted by the EU Space Programme Security Accreditation Board on 1 March. The first Galileo Navigation Message from the new Ground Segment was disseminated on 11 March at 13:39 GMT/14:39 CET. The Control Centres upgrade was completed on 26 March, followed by the Security Monitoring Centres on 10 April. The new PRS Signal-in-Space was first broadcast on 12 April.

"We had some minutes of high pressure at the most critical moment, when switching between versions. Thanks to a smart strategy, preparation, rehearsals and the motivation and competency of everyone involved, we pushed through and succeeded," said Sonia Toribio, ESA's Galileo Ground Segment Manager.

"ESA, the EC, EUSPA and our industrial partners were pursuing a single goal: to serve European citizens with the most accurate and robust GNSS."

The migration did not impact Open Service users, and the stability of the Galileo signal broadcast during the migration was excellent. Final pieces of the puzzle, including uplink and sensor stations, are now being put in place.

"When you consider the extreme precision in time and position of Galileo and the need for this migration to occur in real-time, the project seemed like a chimera. All teams were ready for any possible contingency during the migration, with very limited windows of opportunity. The result could not be more satisfactory: the seamless transition that was not perceived by any user is a testament of the professionality and knowhow of all teams involved," stated Miguel Manteiga Bautista, ESA Galileo Programme Manager.

The System Build 2.0 migration marks a major step forward for European satellite navigation, enhancing the robustness of the Galileo Ground Mission Segment, adding security capabilities, and reinforcing cyber protection. It also prepares the system to accommodate new architectures from Galileo Second Generation.

"This system upgrade allows Europe to turn the page in the provision of secure and reliable navigation services, keeping Galileo at the forefront of global satellite navigation systems," said Ennio Guarino, Head of ESA Galileo and EGNOS Programme Department.

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Galileo at EU
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