The Galileo Second Generation will phase in of new services, improve existing services and increase security
The technology multinational GMV is playing a key role in the Galileo Second Generation (G2G) ground segment.
G2G’s main objectives are to phase in new services, improve existing services, and boost system robustness and security while cutting both operating and maintenance costs, to cement Galileo’s position as one the future’s top GNSS.
Three phases. G2G is divided into several phases. In the first, led by the European Space Agency (ESA), mission requirements were defined at system level. This was followed by a preparation phase, then an implementation phase.
As well as priming several mission-requirement projects, GMV, since 2018, has been heading one of the consortia working on G2G’s complete ground segment during the preparation phase.
Within the preparation phase — shortly before the start of the COVID lockdown — ESA announced the successful end of the first phase before launching a bid invitation for the second phase as the prelude to G2G implementation.
Although publication of the bid invitation for this phase was eventually pushed back until mid-June, GMV never broke off its G2G activities. In recent months GMV has brought new recruitments and partners into the project team while also working on new ideas and kicking off some project activities.
Team members have attended various skills-training courses, some of them gaining certification under SAFe 5 Agilist. During these months, GMV has also been working under new pandemic circumstances with teleworking, virtual meetings and new toolboxes.
First Generation. Galileo First Generation (G1G), running since December 2016, consists of space infrastructure (26 satellites to date) and ground infrastructure. Galileo is now providing 20-cm-precision positioning, navigation and timing services for over 400 million users around the world.
The worldwide Galileo ground segment includes two control centers (Italy and Germany) as well as various tracking, uplink and sensor stations and monitoring and test centers. (Image: ESA)
The European Space Agency has awarded a new framework contract and two new work orders to Thales Alenia Space in France to upgrade the Galileo Mission Segment, the element of the worldwide Galileo ground segment dedicated to delivering navigation services. Included are upgrades to the Galileo Security Monitoring Centre (GSMC) near Paris, and implementation of a second GSMC in Spain, near Madrid.
ESA Director of Navigation Paul Verhoef signed the contract with Thales Alenia Space Senior Vice President of Sales Martin van Schaik on Oct. 17 at ESA’s ESTEC technical centre in Noordwijk, the Netherlands.
“Galileo has already proven to be the highest performing satellite navigation system in the world, even before the constellation is complete,” Verhoef said. “This achievement is the result of the close collaboration between the public sector — the European Commission, the European GNSS Agency and ESA — and our industrial partners throughout Europe.
Contract signing: van Schaik (left) and Verhoef. (Photo: ESA)
“Today I am very happy to announce a continued relationship with Thales Alenia Space in one of the most complex parts of the system, namely the Ground Mission Segment, and thank them for their commitment to the programme.”
The constellation in orbit is only one element of the overall satellite navigation system – the tip of the Galileo iceberg. At the same time as the satellites were being built, tested and launched, a global ground segment was put in place.
Complex System
Establishing Galileo’s ground segment was among the most complex developments ever undertaken by ESA, having to fulfil strict levels of performance, security and safety.
In 2017, responsibility for operating the Galileo ground segment was passed to ESA’s partner organization, the European GNSS Agency (GSA). Nevertheless, ESA continues to be in charge of the maintenance, development and evolution of the ground segment, as well as the development of the space segment.
GSMC upgrade and construction. The first work order contracts Thales Alenia Space as prime contractor to undertake all necessary activities to upgrade the Galileo Mission Segment and the GSMC as part of Galileo’s exploitation phase.
This work includes upgrading Galileo’s system architecture to provide more accurate navigation products for broadcast by Galileo satellites, updating obsolescent elements in the current system, and improving operability linked to the provision of services and enhanced robustness.
This work order also includes the construction of additional uplink stations – tasked with uplinking the latest navigation messages to the Galileo constellation — at the existing Galileo ground station sites of Papeete in French Polynesia and Svalbard in Norway.
A new sensor station — providing a ground-based measurement of Galileo signal quality and precise satellite position — will also be installed at Wallis Island in the Pacific.
Galileo’s Nouméa ground station’s Sensor Station and Uplink Station. (Photo: ESA)
The work order will also augment the capabilities for implementation of the Public Regulated Service (PRS), the single most accurate and secure class of Galileo signals. Encrypted PRS signals will be made available only to authorised governmental users through approved national authorities.
Together, the two GSMCs will ensure the security of the overall Galileo system and manage PRS access and operations.
Security monitoring. The second work order contracts Thales Alenia Space as prime contractor to implement security monitoring functions for Galileo operational assets — including the control centres, service facilities and ground stations.
The integration, qualification, deployment and migration into operational services of the various upgraded segments will be undertaken over the next three years.
ESA has issued these work orders in its role of undertaking the design and development of future upgrades and the technical development of infrastructure as well as overseeing Galileo’s deployment, on behalf of the European Union, Galileo’s owner.
Galileo’s initial services have been running for more than 15 months now, and signals from the satellites in space are routinely serving users all across the world. The functioning of Galileo is dependent on a global network of ground stations, its current extent shown in the map here.
The constellation in orbit is only one element of the overall satellite navigation system – the tip of the Galileo iceberg. At the same time as satellites were being built, tested and launched, a global ground segment has been put in place, extending to some of the world’s loneliest places, from Svalbard in the High Arctic to storm-engulfed Jan Mayen Island, Ascension Island in the Mid Atlantic to Noumea in the South Pacific, Kerguelen in the southern Indian Ocean to Troll base in the Antarctic interior.
Galileo’s global ground segment. (Image: ESA)
Among the latest developments are updated control and mission software for the two Galileo control centres that sit at the heart of this global web: Fucino in Italy generates the accurate navigation messages that are then broadcast through the navigation payloads, and Oberpfaffenhofen in Germany controls the constellation of satellites. A new telemetry, tracking and command station last year arose in Papeete on Tahiti, in the South Pacific.
Establishing Galileo’s ground segment was among the most complex developments ever undertaken by ESA, having to fulfill strict levels of performance, security and safety. Formal responsibility for the operations of this Galileo ground segment was last year passed to ESA’s partner organization, the European Global Navigation Satellite System Agency, or GSA, but ESA continues to be in charge of its maintenance and growth.
Galileo’s Nouméa ground station’s Sensor Station and Uplink Station. (Photo: ESA)
Users don’t have to worry about this ground segment, but it is essential to keeping Galileo services running reliably. The atomic clocks aboard the satellites are accurate to a few nanoseconds, delivering metre-scale positioning precision, but they are prone to drift over time.
Similarly, the orbits of the satellites can be slightly nudged by the gravitational tug of Earth’s slight equatorial bulge and by the Moon and Sun. Even the slight but continuous push of sunlight itself can affect satellites in their orbital paths. The quality of signals received on the ground can be affected by their transit through the ever-changing ionosphere, the electrically active outer layer of Earth’s atmosphere.
Galileo sensor stations, with small omnidirectional receiving antennas around just 50 cm high, are on place around the globe to check the accuracy and signal quality of individual satellites in real time, and work together to pinpoint the current satellite orbits.
These measurements are transmitted via secure satellite communications to Fucino, where they serve as the basis of a set of corrections — accounting for timing or orbital slips — to be uplinked to the satellites via a network of 3-metre-diameter uplink stations for rebroadcast within navigation messages to users, currently updated every 50 minutes.
Considering Galileo is Europe’s largest satellite constellation, timely control of the satellites is essential, enabled by 13 m-diameter telemetry, tracking and command stations in Kiruna, Sweden and Redu, Belgium as well as the equator-hugging Kourou, French Guiana, Reunion, Noumea in New Caledonia and now Papeete sites.
Galileo Station on Gran Canaria. (Photo: ESA)
The ground segment also comprises a set of four Medium-Earth Orbit Local User Terminals serving Galileo’s search and rescue service, at the corners of Europe and facilities for testing Galileo service quality and security — the Timing and Geodetic Validation Facility and two Galileo Security Monitoring Centres.
The Launch and Early Operations Control Centres have the task of bringing new satellites to life, to be handed over to the main Satellite Control Centre in Oberpfaffenhofen within typically a week after launch. Redu in Belgium, set up as Galileo’s In-Orbit Test Centre, then puts these satellites through a complex set of testing and checkouts ahead of them joining the working constellation.
