Galileo: An exciting road ahead toward new capabilities

I/NAV improvements for all Galileo Open Service users is a part of the new Galileo services portfolio. (Image: EUSPA)

In 2023, Galileo continues to provide the world’s most precise satellite navigation information, to more than four billion users worldwide. Galileo services have expanded with many new capabilities that are unique with respect to other GNSS.

EUSPA and ESA continue to enjoy an effective collaboration on the many development, deployment and evolution activities of the Galileo Program, each according to its responsibilities for service provision and system development with the European Commission acting as the program manager.

Stable service performance

The service delivery operations, and the maintenance of the operational systems, are managed by EUSPA, who supervises several contracts that carry-out the day-to-day activities from dedicated control and monitoring centers throughout Europe. The Galileo timing, navigation and SAR/Galileo services provided in 2023 have been delivered with excellent performances that continue to exceed the formal declarations for minimum performance levels (MPL), both in terms of absolute accuracy and overall service availability.

Expansion of service portfolio

Galileo FOC batch three satellites in storage at OHB Systems. (Image: ESA)

The service provision teams have been able to focus on improvements to, and expansion of, the Galileo service portfolio.

OS and I/NAV improvement

Galileo Open Service (OS) users can already benefit from an improved navigation message, being broadcast by the Galileo constellation since mid-2023, which considerably boosts their performance in terms of robustness and time to first fix.

An update of the Galileo OS service definition document (SDD) is planned for the end of this year. This fourth issue of the OS SDD will bring to the users new MPLs (e.g., ranging rate accuracy and ranging accuracy at high percentiles) and improvements of existing MPLs, such as the timeliness of certain notice advisories to Galileo users. This updated OS SDD will also introduce the OS extended operation mode, which is characterized by a gradually degrading ranging accuracy with respect to the nominal operational mode, including outages of the Galileo ground segment, thus increasing the robustness of the OS.

High Accuracy Service

As of the HAS initial service declaration on January 24, Galileo became the first GNSS constellation ever to enable a decimetre-level accuracy, free of charge on a 24/7 basis over most parts of the globe in nominal conditions. The HAS corrections are transmitted directly via the Galileo signal in space (E6-B) and through the internet with the corresponding performance levels systematically met since the declaration. All documentation available here.

OS-NMA

The OS Navigation Message Authentication (OSNMA) will be a free and open access service allowing the users to confirm that received Galileo navigation data has not been modified and originates from the Galileo system, thus increasing the likelihood of detecting spoofing attacks at the data level and significantly contributing to the security of the solution. The OSNMA public observation phase is currently ongoing (gsc-europa.eu/support-to-developers/osnma-public-observation-test-phase). As part of that, the final OSNMA signal in space (SiS) interface control document (ICD) was published in December 2022, while the broadcast of a compliant SiS together with test certificates for the public key infrastructure started in August, marking the start of the OSNMA initial operational capability. The OSNMA initial service declaration will be achieved after the completion of the service validation activities and is targeted for early 2024.

Safety of life

The Galileo contribution to safety of life services (GoSoL) will cover the provision of Galileo signals and of service guarantees to enable the implementation of horizontal ARAIM service supporting aviation users. The service roadmap is currently under definition with a stepwise approach that will include the broadcast of a test ISM before the operational service is provided.

SAR

SAR/Galileo provides accurate, timely, and reliable distress alert data to help rescue authorities assist in distress situations (forward link service). It also acknowledges the receipt of the distress forward link alert to the beacon in distress via the Galileo navigation SiS (return link service). SAR/Galileo is a geographically distributed system, which was extended with a fourth European MEOLUT installed in La Reunion, in operation since November 2022.

The combination of SAR/Galileo space and ground assets provides excellent performance levels with a mean location accuracy of less than 800 m and a return link delivery latency of less than 1 min, which assisted in the rescue of approximately 1,400 people within EU territories in 2022.

Utilizing the return link service capabilities brings new innovations that further contribute to the global emergency space operations as Galileo moves forward to the implementation phase of the emergency warning satellite service (EWSS). The EWSS will provide national civil protection authorities with a satellite broadcasting capability to broadcast on-demand authenticated alerts to a precise target area and its population directly to any device capable of processing Galileo signals.

Reference documents for each of the above services can be found at the EUSPA European GNSS Service Center website, including technical notes, interface control documents and service declaration documents.

Image: European Space Agency (ESA)

Full operational capability infrastructure development toward completion

Space segment

The production of the third batch of Galileo FOC satellites, by the satellite manufacturer OHB Systems, has been completed for an overall amount of 12 satellites. The acceptance review for the last couple of spacecraft took place in June.

This amounts to an overall production by OHB Systems of 34 Galileo FOC Satellites (14 satellites in batch one, eight satellites in batch two and 12 satellites in batch three) of which 24 are in orbit. The remaining 10 satellites are in storage waiting for the next launch opportunity in 2024.

Ground segment

G2SB1 engineering model payload testing at ESA ESTEC. (Image: ESA)

The ground segment is going through a major upgrade with the roll-out of the new System Build 2.0 infrastructure in support of public regulated service IOC and open service FOC.

The new version of the ground mission segment developed by Thales Alenia Space France will be oriented to increase service robustness and resilience, besides high performance. It will provide virtualized hardware and software infrastructure at the Galileo Control Centers, triple receiver chain redundancy in the sensor stations’ remote sites and two additional sites located in Wallis (Pacific Ocean) and Bonaire (Caribbean Sea) to increase global coverage with 15 sites overall. A new mission monitoring capability has been implemented for the operators using the SAFE/Agile methodology. Furthermore, a system extended contingency mode will be implemented to cope with outages lasting up to seven days with smooth navigation performance degradation.

A new version of the Galileo Security Facility will be deployed at the Galileo Security Monitoring Centers offering an evolution of the public regulated service (PRS) capabilities through new enhanced SiS access control. Furthermore, a new state of the art cyber security monitoring system will be implemented.

The System Build 2.0 infrastructure qualification was completed by ESA in July. Migration in operation is based on an innovative concept consisting of a replica of the operational chains to ensure seamless transition from the current system in operation to the newly deployed one. The completion of the migration into operations is planned for the beginning of 2024, with the schedule being continuously monitored at the program level.

Galileo Second Generation: a constellation of state-of-the-art procurements. (Image: ESA)

An upgrade of the ground control segment in charge of command and control of the constellation is under qualification by the industrial consortium led by GMV. It will provide additional flexibility to allow for deployment in between launches and to address resolution of hardware and software obsolescence, including cyber security, operability improvements and a security monitoring overlay. Furthermore, it will upgrade the Telemetry Tracking and Control (TTC) station in Redu, Belgium, and deploy an additional station in Fucino, Italy, co-located with the Galileo Control Center, bringing to nine the overall number of TTC stations.

Second generation fast forward

Galileo’s second generation (G2G) will introduce many innovative technologies to offer unprecedented precision, robustness, and flexibility.

For the development of G2G activities 2023 was a key year, with the development of the first batch of G2 satellites, the start of all contracts for in-orbit validation of the ground segment and system test beds and the preparation of the initial operational capability (IOC) design, through the consolidation of the mission/service roadmaps with the EC, EUSPA, and the delegates from EU member states.

This year, Europe has taken the necessary steps to unchain the development of key GNSS features, which will exponentially enhance GNSS accuracy for the worldwide communities in the future:

• New and improved services.
• Unique flexibility of ground and space systems to enable 12-18 months service time to market, without the need for constellation replenishment.
• Upgraded robustness of key infrastructure items.
• State of the art GNSS technology leading to centimeter-level precision.
• New GNSS signals, including extended data capacity for added value services.
• And of course, as a key factor, a full backward compatibility with Galileo First Generation and other GNSS systems.

G2G: Incremental steps for enhanced capabilities over the next decade

The ESA completed the G2G system preliminary design review in July, focused on three key incremental phases of the G2G:

• G2G In-Orbit Validation (G2GIOV): specification, design and validation activities for the sake of ensuring the full development of the first batch of G2G satellites and all the associated infrastructure for launch and early orbit phase, in-orbit testing, in-orbit validation, initial enhancement of Galileo services and addition of new Galileo service components.
• G2G Initial Operational Capability (G2GIOC): design and specifications required for the complementary procurements that will ensure new Galileo services, as enabled by G2G infrastructure, including both the second batch of G2G satellites and the G2G ground segment.
• G2G Full Operational Capability (G2GFOC): Identification of key technological enablers and additional capabilities required for final G2G implementation, including the bridge to future synergies with other EU and ESA programs.

G2G in-orbit validation infrastructure – satellite hardware under validation

G2SB1 acoustic testing in Rome and structural model arrival at ESA ESTEC. (Image: ESA)

The two parallel contracts with Thales Alenia Space and Airbus to develop and manufacture each of six G2G batch one satellites (G2SB1A and B) achieved key milestones this year.

On the G2SB1 satellite A side, the prime contractor tested engineering model payloads and structural models at its premises and delivered them to ESA’s Technology Center (ESTEC). The validation of the new G2G payload capabilities and the key mechanical, vibration and acoustical testing milestones have been achieved.

These satellites will provide the following key innovations: reconfigurable fully digital navigation payload; point-to-point connection between satellites by inter-satellite-link for command and control, and ranging functionalities; electric propulsion for orbit-raising capabilities; advanced jamming and spoofing protection mechanisms; on-board authentication capabilities; increased ground-to-space data rate; and improved time reference (number of clocks and advanced clock monitoring functions).

Key mechanical and launch-related tests on the structural models stacked configurations were performed in the last quarter of this year, in order to simulate the launcher environment and satellite separation dynamics.

On the G2SB1 satellite B and the PHM and RAFS clock manufacturing sides, activities are ongoing as planned, with key HW infrastructure developed and tested in the respective Industrial Primes premises.

This included as key events in 2023 the full testing of the satellite advanced engineering model antenna and the creation of a satellite atomic clock farm in industry premises to produce the more than 70 atomic clocks required for the 12 G2 batch one satellites.

The next steps for these contracts are the completion of the equipment and satellite CDRs, expected in the coming months, in order to engage (starting at the end of 2024) with the critical system compatibility test campaigns of the G2G IOV ground segment infrastructure and system engineering test beds under development.

Galileo Second Generation batch one satellites. (Image: ESA)

G2G in-orbit validation infrastructure – ground segment and test beds in full development

The key system engineering, ground segment and test beds infrastructure procurements were all awarded during the first semester of 2023, giving EC/EUSPA/ESA and the industrial teams a brief moment of respite and celebration.

Following a competition process that encompassed about 12 months of detailed technical, management and legal interactions, 11 industrial prime contractors were selected for a set of contracts engaging about $1 billion euros of public sector investment:

• Four contracts for system engineering, signal and performance, system validation and security and PRS activities.
• Four contracts for ground segment in-orbit validation infrastructure.
• Three contracts for system test bed activities plus a series of technological developments in the receivers and constellation simulation side.
• Once completed in the years to come, these infrastructure developments will ensure not only the launch and early orbit phasing and in-orbit validation of the novel G2G satellite’s capabilities, but also enable the provision to all world users of enhanced Galileo services.

G2G satellites stacked configuration for launcher simulated test at ESA ESTEC. (Image: ESA)

G2G initial and final operational capability moving ahead

In line with the outcomes of the system preliminary design review, two new lines of GNSS improvements are well underway at program level.
In the area of G2G initial operational capability (IOC), which will provide new G2G initial services, an extensive preparatory work has been performed by EUSPA in order to derive the mission needs (as defined by the EC and its Member States), into a set of service evolution roadmaps for the more than one dozen Galileo services.

This work has been supported by ESA dossiers providing incremental implementation of these services, in a continuous improvement ramp-up process, which guarantees backward compatibility and seamless enhancement.

The relevant procurements that will enable, in combination with the in-orbit validation infrastructure, the provision of these services are currently under consolidation:

• G2G IOC ground segment, with an initial version to be procured in 2024.
• G2G satellites batch two, which is expected to start its competitive procurement procedure in the second part of the EU’s 2021-2028 multi-financial framework.

In addition, work is well advanced in the definition of the key technological developments and system trade-offs that will be analyzed for inclusion in the G2G final operational capability (FOC), expected early in the 2030s.

Critical technologies being analyzed include optical inter-satellite links, advanced governmental payloads, new ground segment and signal technologies and in-space constellation monitoring, among others. ESA expects to complete the preparation of the system-critical design review by the end of 2024 or early 2025 and to submit it for in-depth review by the EC, EUSPA and European member states stakeholders.

Conclusions

Galileo keeps providing continuous and stable services to users with new enhanced capabilities offering high accuracy, authentication and faster time to first fix. The space and ground infrastructure development for the first generation is progressing toward public regulated service IOC and open service FOC.
In parallel, for G2G, hardware production of the new satellites is well under way and the ground segment development has started to maintain Galileo competitive with the other GNSS.

We continue to strive toward achieving the vision defined at the end of the previous decade: “If you can imagine a novel satellite navigation service, we will implement it in 12-18 months.”

We have an exciting road ahead.

G2G FOC perspectives. (Image: ESA)