Minimize Galileo navigation program FOC

Galileo navigation program: FOC (Full Operational Capability)

Spacecraft     Launch    Mission Status     Navigation Payload    SAR/Galileo Payload    Ground Segment

Galileo is a joint initiative of the European Commission (EC) and the European Space Agency (ESA). Galileo will be Europe’s own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It will be inter-operable with GPS and GLONASS, the two other GNSS (Global Navigation Satellite Systems). The complete system consists of:

• A space segment of 30 MEO satellites in 3 planes inclined at 56º

• A launch segment to place the satellites into their operational orbits

• A control ground segment for monitoring and control of the satellites

• A mission ground segment managing all mission specific data

• A user ground segment of equipment capable of receiving and using Galileo signals


Figure 1: The Galileo constellation of 30 spacecraft (image credit: ESA)

The Galileo program has been structured into two phases:

1) IOV (In-Orbit Validation) phase: IOV consists of tests and the operation of four satellites and their related ground infrastructure. The first two IOV satellites were launched on Oct. 21, 2011. The second pair of IOV satellites, IOV-3 and IOV-4, were launched on Oct. 12, 2012.

2) FOC (Full Operational Capability) phase: FOC consists of the deployment of the remaining ground and space infrastructure. It includes an initial operational capability phase of 18 operational satellites. The full system will consist of 30 satellites, control centers located in Europe and a network of sensor stations and uplink stations installed around the globe.

On July 1, 2008, the EC and ESA launched the procurement process of Galileo. Political decisions made by the European Parliament and the Council in 2007 resulted in the allocation of a budget for the European satellite navigation programs EGNOS and Galileo and provided for an agreement on the governance structure of the programs.

This framework provides for the deployment of the FOC (Full Operational Capability) of Galileo under a public procurement scheme, entirely financed out of the European Community budget. The European Commission (EC) acts as program manager and contracting authority, and ESA acts as its procurement and design agent.

The procurement initiated includes six WPs (Work Packages). In this setup, ESA functions in its role as the designated procurement agent on behalf of the European Union: 1)

• WP1 deals with system support services.
On January 7, 2010, the EC awarded a contract to TAS-I (Thales Alenia Space-Italia). 2)

• WP2 is dedicated for the ground mission.

• WP3 covers the ground control.

• WP4 covers the development of the spacecraft.
On January 7, 2010, the EC awarded a contract for a first order of 14 satellites to OHB System AG of Bremen, Germany. OHB System teamed with SSTL (Surrey Satellite Technology Ltd.), UK. - Note: In 2012, the OHB-SSTL consortium was awarded a second contract to supply a further 8 spacecraft for the program.

• WP5 deals with the launch services of the constellation.
On January 7, 2010, the EC awarded a contract to Arianespace of France.

• WP6 is dedicated to the preparation activities as well as all the operations services of the fully-deployed Galileo system.

- WP6 Work Order 1 covers all activities related to the completion of the IOV (Galileo In Orbit Validation) activities – the first four Galileo satellites are due for launch in 2011.

- WP6 Work Order 2 is dedicated to the implementation and activities of an integrated engineering team supporting ESA for system operations.

- WP6 Work Order 3 deals with the completion of deployment of operations for Galileo’s FOC, scheduled for 2014.

- WP6 Work Order 4 covers the full deployment of the two Galileo Ground Control Centers, in Germany at Oberpfaffenhofen and in Italy at Fucino.
On Oct. 25, 2010, ESA signed a contract with Spaceopal, a joint undertaking between the Italian company Telespazio and the German firm GfR (Gesellschaft für Raumfahrtanwendungen mbH). GfR has been set up by the German Aerospace Center (DLR) to provide operational services for the Galileo system. 3)

Table 1: Overview of the Galileo program Work Packages 1) 2) 3)

Contract kick-off with OHB as the prime of the FOC space segment WP1 (Work Package 1) took place in late January 2010; two years later, again after highly competitive bidding and based on the performance in WP1, OHB was also able win the space segment Work Order 2 contract, thus increasing the total number of satellites to be built to 22. The Galileo FOC project is characterized by an extremely challenging schedule, which foresees a delivery of a finalized satellite every six weeks. 4)

Development of the Galileo Satellites

For the Galileo FOC development phase, OHB System of Bremen, Germany teamed with SSTL (Surrey Satellite Technology Ltd.), UK. Within this team, OHB-System is the prime contractor and is responsible for the development of the 22 spacecraft. SSTL is fully responsible for the satellite payloads. The system level activities will be led by OHB-System, making use of the experience gained by SSTL through its GIOVE-A activities. 5)

ESA is already procuring 4 satellites from Astrium through its IOV (In-Orbit Validation) program which brings the number of operational Galileo satellites now under contract to 18.


Figure 2: Illustration of the Galileo FOC spacecraft (image credit: OHB System)

Spacecraft of the FOC series:

The production of the spacecraft series, with a delivery schedule of each pair of satellites in periods of 3 months, requires an assembly line production technique to meet the time table. This can only be achieved by implementing a modular satellite design.

The FOC satellites, 22 in total, provide the same operational services as their predecessors, but they are built by a new industrial team: OHB in Bremen, Germany build the satellites with Surrey Satellite Technology Ltd in Guildford, UK contributing the navigation payloads.


Figure 3: Galileo FOC solar wing deployment being checked at ESA/ESTEC (image credit: ESA)

Legend to Figure 3: The navigation satellite’s pair of 1 m x 5 m solar wings, carrying more than 2500 state-of-the-art gallium arsenide solar cells, will power the satellite during its 12 year working life. 6)

The design of the 22 Galileo FOC satellites is quite different with respect to that of their four Galileo IOV (In-orbit Verification) counterparts. For technical and cost reasons, only half of the units aboard were re-used from IOV. Part of the rationale are also more demanding requirements for FOC compared with IOV, e.g. an increased RF signal output power level, tougher radiation requirements, and harsher launch load requirements to name a few. Hence, qualification on subsystem and system level had to be done from scratch (Ref. 4).

Fulfilment of ESA's FOC satellite requirements was achieved through a simple and robust design, leading to a satellite of ~720 kg with a provided power production of 1.9 kW (end of life), which provides navigation signals in L1, E5, and E6 bands, as well as Search-and-Rescue services. The FOC satellite design is depicted in Figure 4.


Figure 4: Galileo FOC satellite design with “plug-in” propulsion module (image credit: OHB System)

A lot of OHB's development work went into optimizing the design for series production. It was identified that in order to meet the production cadence requirement of six weeks, parallelization of work on each satellite would have to be achieved. As this is very hard to achieve at late stages of integration and testing of a satellite, the focus was put in particular on the early stages of MAIT (Manufacturing, Assembly, Integration, and Testing).

The satellites are integrated in seven modules, depicted also in Figure 5:

• the propulsion module (integrated at the propulsion supplier, Moog Inc.)

• the solar generator module (integrated at the solar generator supplier)

• clock, antenna, and payload core module (integrated at SSTL, OHB's co-prime, responsible for the payload, located in Guildford, UK)

• the center and the platform core modules (integrated at OHB's premises in Bremen, Germany).

Work on these seven modules can be executed independently from each other and in parallel to each other. A good example for that is the propulsion module. While in most satellites, the propulsion system is distributed over the entire spacecraft, the modularity intended for Galileo FOC let OHB designers to mount all the propulsion-related systems on one panel, which can be integrated and replaced also late in the MAIT process (as depicted in Figure 4). The big access panel in the launch dispenser-facing side of the satellite increases the ease of access into the satellite, also at late stages of the assembly.

In the next step of integration after module integration, the seven modules form the platform and the payload (see Figure 2), which also can be treated independently from each other and in parallel to each other (payload at SSTL, platform at OHB). Final integration of payload and platform and system level tests are then also carried out at OHB. Subsequently, the integrated and tested satellites are shipped to ETS (European Test Services) in Noordwijk, The Netherlands, for the environmental test campaigns.

Development work was based on early availability of functional models of the board computers. These were used in subsystem breadboards to facilitate software development with hardware in the loop as early on as possible. Further development work was carried out in two thermal development models that focussed on the two thermally critical areas: firstly, the clock panel, where clock temperature stability was demonstrated, and secondly the area of the travelling wave tubes, where sufficient high dissipation on limited radiator area was validated.

On system level, a flat-sat engineering model was employed to check out inter-subsystem compatibility and interaction. A further payload-only engineering model was employed by SSTL at their premises for payload-level development work.


Figure 5: Illustration of satellite modules (image credit: OHB System)

MAIT (Manufacturing, Assembly, Integration, and Testing): The MAIT approach picks up on the design of the satellite and focuses on the series production and the production cadence as well. The production is based on an island mode, while the check-out equipment and ground support equipment stays in place, it is the satellites that move from station to station. The activities that are executed at a given station are trimmed to give all stations more or less the same stay duration. After that duration, all satellites move forward one station. Primary goal is to keep the flow of satellites going, meaning to avoid “clogging” the production pipeline, as this would have impact on all previous islands, which cannot turn to the next satellite in line, whereas all succeeding islands or stations would “run dry”. Hence margin for trouble shouting must be taken into account. For larger issues in the production pipeline, there is a so-called “recovery island” foreseen, which is equipped with all types of ground support equipment which can handle problems that take several days or even weeks to resolve while the rest of the pipeline continues normally.

Spacecraft launch mass

730 kg (including 63 kg of fuel and 30 kg margin)

Spacecraft body size, span

2.5 m x 1.2 m x 1.1 m

Spacecraft span

14.67 m

Overall size at launch

2.91 m 1.70 mx 1.40 m

Spacecraft design life

≥12 years in space, ≥ 5 years ground storage


MEO, r=29800 km, inclination = 56º, 3 orbital planes with RAAN spacing of 120º, at EOL transfer to graveyard orbit

Clock frequency stability

PHM (Passive Hydrogen Maser):<4.5 x 10-14 at 30000 s
RAFS (Rubidium Atomic Frequency Standard): <5.1 x 10-14 at 10000 s

Navigation signal
- Minimum EIRP (EOC)
- Bandwidth

3 bands (E5, E6, L1)
- E5: 32.84 dBW, E6: 33.49 dBW, L1: 35.63 dBW
- E5 : 92.07 MHz, E6: 50.00 MHz, L1: 50.00 MHz

Design approach

Satellite consists of 7 modules, resulting in simple interfaces, enabling parallelized MAIT (Manufacturing, Assembly, Integration and Testing)

Satellite reliability

0.811/12 years (w/o SAR PL)

Failure tolerance

- Full performance maintained after single failure
- Autonomous operation and failure recovery features


TEMIC TSC695 32-bit RISC processor (radiation hardened)
- Processing capability: 14 MIPS

Satellite radiation hardness

MEO compliant

Up- / Downlink

2048 MHz Rx / 2225 MHz Ty (encrypted TMTC)
406 MHz Rx (SAR)
5005 MHz Rx (MISANT)
1191.795 MHz, 1278.75 MHz, 1575.42 MHz Tx (NAV), 1544 MHz Tx (SAR)

Common Security Unit
- S-band security L1
- C-band security mission data
- S-band / C-band security L2
- S-band / C-band security L3
- L-and security

Combines functions for payload and platform
- Encryption/decryption, authentication, anti-replay
- Authentication (COMSEC)
- Encryption/decryption, authentication, anti-replay
- Decryption
- Encrypted navigation signals (NAVSEC)

- Primary voltage
- Average power consumption
- Solar generator
Total power produced
Battery type / capacity

- 50 V, regulated
- 1.75 kW (EOL)
- 2 wings, 2 panels each, triple junction GaAs
- 1.9 W (EOL)
- Li-ion, 3.8 kWh


Aluminum sandwich panel design featuring 3 tillable panels and access panels allow late and easy access


3-axis stabilized
- ≤0.3º pitch/roll, ≤1º yaw
- Fine and coarse sun sensors, gyro, Earth horizon sensors
- Reaction wheels, thrusters, magnetorquers


Slanted N2H4 monopropellant thrusters (2 x 4 nozzles with 1 N thrust each, fully redundant), blowdown pressurization

Table 2: Key parameters of the Galileo spacecraft 7)


Figure 6: The main antenna of the FM2 satellite is being inspected at ESTEC prior to mass property testing in August 2013 (image credit: ESA, Anneke Le Floc'h) 8)

Nominal orbit of the Galileo constellation: The Galileo constellation is composed of a total of 30 MEO (Medium Earth Orbit) satellites, of which 6 are spares (Figure 1). Each satellite will broadcast precise time signals, ephemeris and other data. The Galileo satellite constellation has been optimized to the following nominal constellation specifications:

- Circular orbits (satellite altitude of 23,222 km), orbital inclination of 56°, three equally spaced orbital planes.

- Eight operational satellites, equally spaced in each plane, two spare satellite (also transmitting) in each plane.

Launch: On August 22, 2014, the first two Galileo FOC satellites,FOC-1 (FM1) and FOC-2 (FM2), were launched from Kourou on the Soyuz ST-B vehicle (flight VS09), operated by Arianespace. 9)

Unfortunately, the orbit injection of the FOC spacecraft didn't occur as planned and the satellites did not reach their intended orbital position.

The liftoff and first part of the mission proceeded nominally, leading to the release of the satellites according to the planned timetable, and reception of signals from the satellites. It was only a certain time after the separation of the satellites that the ongoing analysis of the data provided by the telemetry stations, operated by ESA and the French space agency, CNES, showed that the satellites were not in the expected orbit.

The targeted orbit was circular, inclined at 56º with a semi major axis of 29,900 km. The satellites are now in an elliptical orbit, with an eccentricity of 0.23, a semi major axis of 26,200 km and inclined at 49.8º.

According to the initial analyses, an anomaly is thought to have occurred during the flight phase involving the Fregat upper stage, causing the satellites to be injected into a noncompliant orbit.


Figure 7: Photo of the Galileo FOC-3 and FOC-4 satellites fitted onto dispenser (image credit: ESA/CNES/ARIANESPACE-Service Optique CSG) 10)


Figure 8: Illustration of satellite configurations in various mission phases (image credit: OHB System)

Launch: The seventh and eighth Galileo satellites (FOC-3 and FOC-4) were successfully launched together on March 27, 2015 (21:46:18 UTC) atop a Soyuz-STB/Fregat vehicle (VS11) from Europe's Spaceport (Kourou, ELS) in French Guiana. 11) 12)

All the Soyuz stages performed as planned, with the Fregat upper stage releasing the satellites into their target orbit close to 23, 500 km altitude, around 3 hours 48 minutes after liftoff. Shortly thereafter, the two satellites sent their first signals from orbit, which were received by the CNES control center in Toulouse. 13)

Following initial checks, run jointly by ESA and France’s CNES space agency from the CNES Toulouse center, the two satellites will be handed over to the Galileo Control Center in Oberpfaffenhofen, Germany and the Galileo in-orbit testing facility in Redu, Belgium for testing before they are commissioned for operational service. This is expected in mid-year.


Figure 9: Artist's view of the protective launcher fairing which jettisoned at 3 min 29 sec after launch, revealing the two Galileo satellites attached to their dispenser atop the Fregat upper stage (image credit: Arianespace, ESA)

Launch: The Galileo-9 and -10 satellites (FOC-5 and FOC-6) were launched atop a Soyuz rocket at 02:08 GMT on September 11, 2015 from Kourou, Europe’s Spaceport in French Guiana. 14) 15) 16)

All the Soyuz stages performed as planned, with the Fregat upper stage releasing the satellites into their target orbit close to 23,500 km altitude, around 3 hours and 48 minutes after liftoff. Shortly thereafter, they sent their first “sign of life” to ESOC (European Space Operation Center) in Darmstadt, Germany. Over the next few days, the two satellites will also be undergoing preliminary function testing.

Two further Galileo satellites are still scheduled for launch by end of 2015. These satellites have completed testing at ESA/ESTEC in Noordwijk, the Netherlands, with the next two satellites also undergoing their own test campaigns.

Next year the deployment of the Galileo system will be boosted by the entry into operation of a specially customized Ariane 5 launcher that can double, from two to four, the number of satellites that can be inserted into orbit with a single launch.

Launch: The Galileo-11 and -12 satellites (FOC-7 and FOC-8) were launched atop a Soyuz STB/Fregat rocket at 11:51:56 GMT on December 17, 2015 from Kourou, Europe’s Spaceport in French Guiana. 17)

Launch: The Galileo-13 and -14 satellites (FOC-9 and FOC-10) lifted off together at 08:48 GMT on May 24, 2016 atop a Soyuz rocket from French Guiana. The twin Galileo spacecraft were deployed into orbit close to 23,522 km altitude, at 3 hours and 48 minutes after liftoff. The coming days will see a careful sequence of orbital fine-tuning to bring them to their final working orbit, followed by a testing phase so that they can join the working constellation later this year. 18)

- “Today’s launch brings Europe’s Galileo constellation halfway to completion, in terms of numbers,” remarked Paul Verhoef, ESA’s Director of the Galileo Program and Navigation-related Activities. “It is also significant as Galileo’s last flight by Soyuz this year before the first launch using a customized Ariane 5 to carry four rather than two satellites each time – which is set to occur this autumn.”

- Known by their nicknames Danielè and Alizée, another two Galileo FOC satellites developed and built by OHB System AG, have been successfully launched on board a Soyuz launcher, which lifted off from the Kourou Space Center in French Guiana. 19)

Launch: On November 17, 2016 (13:06 :48 UTC), a quartet of Galileo satellites (Galileo 15-18), each with a mass between 715 kg and 717 kg, and a combined liftoff mass of 2,865 kg, was launched and deployed by Ariane 5 into a circular orbit during a mission lasting just under four hours. The Ariane 5 launch, designated Flight VA233 in Arianespace’s numbering system, was from the Kourou Spaceport in French Guiana. 20) 21)

Flight VA233 marked Arianespace’s first use of its heavy-lift Ariane 5 to loft Galileo satellites, following seven previous missions with the company’s medium-lift Soyuz. The Soyuz vehicles carried a pair of Galileo spacecraft on each flight, delivering a total of 14 navigation satellites into orbit since 2011.

The Galileo satellites are at their target altitude, after a flawless release from the new dispenser designed to handle four satellites. Over the next few days, engineers will nudge the satellites into their final working orbits and begin tests to ensure they are ready to join the constellation. This is expected to take six months or so. This mission brings the Galileo system to 18 satellites.


Figure 10: Above Earth's atmosphere, Ariane’s aerodynamic fairing is jettisoned and the four Galileo satellites ‘see’ space for the first time (image credit: ESA, P. Caril) 22)

Launch: On December 12, 2017, a quartet of Galileo satellites (Galileo 19-22), each with a mass between 715 kg and 717 kg, were launched on Ariane-5 ES in Kourou at 18:36 GMT (flight VA240). The first pair of satellites was released almost 3 hours 36 minutes after liftoff, while the second pair separated 20 minutes later. 23) 24)

- The satellites were released into their target 22,922 km altitude orbit by the dispenser atop the Ariane-5 upper stage. In the coming days, this quartet will be steered into their final working orbits. There, they will begin around six months of tests – performed by the European Global Navigation Satellite System Agency (GSA) – to check they are ready to join the working Galileo constellation.

- This mission brings the Galileo system to 22 satellites. Initial Services of the constellation began almost a year ago, on 15 December 2016.

- “Today’s launch is another great achievement, taking us within one step of completing the constellation,” remarked Jan Wörner, ESA’s Director General. “It is a great achievement of our industrial partners OHB (DE) and SSTL (GB) for the satellites, as well as Thales Alenia Space (FR, IT) and Airbus Defense and Space (GB, FR) for the ground segment and all their subcontractors throughout Europe, that Europe now has a formidable global satellite navigation system with remarkable performance.”

- Paul Verhoef, ESA’s Director of Navigation, said: “ESA is the design agent, system engineer and procurement agent of Galileo on behalf of the European Commission. Galileo is now an operating reality, so, in July 2017, operational oversight of the system was passed to the GSA. Accordingly, GSA took control of these satellites as soon as they separated from their launcher, with ESA maintaining an advisory role. This productive partnership will continue with the next Galileo launch, by Ariane-5 in mid-2018.”

- “Meanwhile, ESA is also working with the European Commission and GSA on dedicated research and development efforts and system design to begin the procurement of the Galileo Second Generation, along with other future navigation technologies.”

- Next year’s launch of another quartet will bring the 24-satellite Galileo constellation to the point of completion, plus two orbital spares.

Launch: On 25 July 2018 (11:25:01 UTC), a quartet of Galileo satellites (23-26, Galileo FOC 19-22) was launched on an Ariane-5 ES vehicle (Flight VA244) of Arianespace from Kourou. The first pair of 715 kg satellites was released almost 3 hours 36 minutes after liftoff, while the second pair separated 20 minutes later. 25) 26)

They were released into their target 22 922 km-altitude orbit ( MEO, 56º inclination) by the dispenser atop the Ariane-5 upper stage. In the coming days, this quartet will be steered into their final working orbits by the French space agency CNES, under contract to the Galileo operator SpaceOpal for the European Global Navigation Satellite System Agency (GSA). There, they will begin around six months of tests by SpaceOpal to verify their operational readiness so they can join the working Galileo constellation.

In July 2017, ESA officially transferred the supervision of Galileo in-orbit operations to the European Global Navigation Satellite Systems Agency (GSA), on behalf of the European Union. After the VA244 launch, the GSA will be responsible for operating the satellites as soon as they are separated from the launcher. These operations of setting up and operating the system will be done in collaboration with ESA.

The constellation will count 24 operational satellites plus in-orbit spares, of which 22 already have been put into orbit by Arianespace.

Figure 11: Completing the constellation. On 25 July 4 Europe’s next four Galileo satellites will be launched into orbit by Ariane 5 from Europe’s Spaceport in French Guiana. With this launch the Galileo constellation will reach 26 satellites in space, completing the constellation in overall numbers although further launches are needed to place back-up satellites in orbit. The launch comes at a time when Galileo is into its second year of Initial Operations, with a signal that is better than expected and that is now usable in all new mobile phones. This video looks at Galileo’s story so far and the way forward, interviewing Paul Verhoef, ESA Director of Navigation, and Valter Alpe, Galileo’s Satellite Production and Launch Campaign Manager (video credit: ESA, Published on 24 July 2018)

Mission status:

• April 29, 2020: As European governments plan their phased recoveries from the lockdown states triggered by the COVID-19 pandemic, the positioning delivered through satellite navigation is becoming more important than ever before. Location is a key requirement when attempting to monitor and map the spread of a disease and satnav is one of the main tools supporting this. 27)

- Since the outbreak of the coronavirus earlier this year, many apps have been developed that use satnav-based location data to monitor the global spread of the virus and to map outbreaks of the COVID-19 disease. Satnav based apps are also proving their usefulness by helping people to implement social distancing in queues and other public spaces.

- The Romanian company RISE has developed an app called CovTrack, which monitors people in your vicinity made identifiable via Bluetooth connections to your mobile phone and stores the identification data of these devices.

- By pressing a button you can access the database in which the unique identifiers of the mobile phones are registered (without having access to any personal data of these mobile phone users), to verify whether the persons with whom you came in contact have subsequently been confirmed with COVID-19. If you have identified a potential contact, you can refer to the relevant authorities whether that contact requires your inclusion among the monitored persons, or even testing for COVID-19.

Figure 12: CovTrack Infographic - HD. CovTrack, developed on a pro-bono basis, is a spin-off from the existing AGORA project for festival management, supported through ESA’s Navigation Innovation and Support Program (NAVISP), focused on future navigation technologies (video credit: ESA)

- ESA’s partner agency the GSA, European Global Navigation Satellite System Agency, working with the assistance of the European Commission, has put together a repository of such apps, available here.

- This list, based on apps that are already working and available in app stores, includes practical apps that facilitate the daily lives of citizens, such as by helping them to manage queues in supermarkets, pharmacies and public spaces or by facilitating the logistics of goods, which has become more complicated in the current situation.

- Europe’s Galileo, currently embedded in over 1.3 billion smartphones and devices worldwide, is helping to increase satnav accuracy and availability, especially in urban areas. Is your own smartphone or device making use of Galileo, the most accurate satnav system? You can check here.

- The GSA is also developing its own Galileo-enabled application, Galileo for Green Lane, to monitor and ease the circulation of goods between EU Member States while identifying potential congestion at Green Lane border crossings, and thus ensuring that EU citizens can access the needed supplies of critical goods.

• February 14, 2020: Eutelsat Communications has informed all that the GEO-3 payload of the European Geostationary Navigation Overlay System (EGNOS), a hosted payload aboard the company's EUTELSAT 5 West B satellite, has successfully entered into service. 28)

- EUTELSAT 5 West B is hosting the Eutelsat-procured EGNOS payload under a 15-year agreement that was signed in 2017 with the European Global Navigation Satellite Systems Agency (GSA). The contract also includes technical services and a European ground infrastructure, including two gateways installed at Eutelsat’s Rambouillet and Cagliari teleports.

- Yohann Leroy, Eutelsat’s Deputy CEO and Chief Technical Officer, said that the firm is proud of the collaboration with customer GSA, its partners including the European Space Agency (ESA), and its suppliers, culminating in the entry into service of this next generation technology of EGNOS on EUTELSAT 5 West B. Eutelsat is delighted to host this payload, which will significantly enhance the performance of global navigation satellite systems across Europe, notably Galileo, in the coming years.

- Pascal Claudel, GSA Acting Executive Director and COO, added that with this new payload in service, EGNOS is moving toward the transition to its new generation. This has been done thanks to the constructive collaboration with Eutelsat. Delivery and continuity of satellite services are part of the company's mission as delegated by the European Commission. It is essential that the GSA ensures these services to support economic growth and that the European Union’s citizens and companies can benefit from the latest GNSS technology.

• January 23, 2020: As well as providing global navigation services, Europe’s Galileo satellite constellation is contributing to saving more than 2000 lives annually by relaying SOS messages to first responders. And from now on the satellites will reply to these messages, assuring people in danger that help is on the way. 29)

- This ESA-design ‘return link’ system, unique to Galileo, was declared operational this week, during the 12th European Space Conference in Belgium. The delivery time for the return link acknowledgement messages from initial emergency beacon activation is expected to be a couple of minutes in the majority of cases, up to 30 minutes maximum, depending primarily on the time it takes to detect and locate the alert.

- “Anyone in trouble will now receive solid confirmation, through an indication on their activated beacon, informing them that search and rescue services have been informed of their alert and location,” explains ESA’s Galileo principal search and rescue engineer Igor Stojkovic. “For anyone in a tough situation, such knowledge could make a big difference.”

- All but the first two out of 26 Galileo satellites carry a Cospas-Sarsat search and rescue package. At only 8 kg in mass, these life-saving payloads consume just 3% of onboard power, with their receive-transmit repeater housed next to the main navigation antenna.

- Founded by Canada, France, Russia and the US in 1979, Cospas-Sarsat began with payloads on LEO (Low Earth Orbiting) satellites, whose rapid orbital motion allows Doppler ranging of distress signals, to pinpoint their location. The drawback is these fly so close to Earth that their field of view is comparatively small.

- GEO (Geostationary Earth Orbiting) satellites went on to host Cospas-Sarsat payloads. These see much more of the planet, but because they are motionless relative to Earth’s surface, Doppler ranging is not possible.

- MEO (Medium Earth Orbiting) satellites such as Galileo – orbiting at 23,222 km altitude – offer the best of both worlds, providing a wide ground view by multiple satellites combined with time-of-arrival and Doppler ranging techniques to localize SOS signals. This improves the maximum signal detection time from four hours to less than five minutes, down to 1 or 2 km (within a formal specification of 5 km within 10 minutes).

- Galileo’s Search and Rescue service is Europe’s contribution to Cospas-Sarsat, operated by the European GSA (Global Navigation Satellite System Agency), and designed and developed at ESA. As the overall Galileo system architect and design authority, ESA has been responsible for the interface between the core Galileo infrastructure to the Return Link Service Provider facility, procured by the European Commission and operated by French space agency CNES.

- The Cospas-Sarsat satellite repeaters are supplemented by a trio of ground stations at the corners of Europe, known as Medium-Earth Orbit Local User Terminals (MEOLUTs), based in Norway’s Spitsbergen Islands, Cyprus and Spain’s Canary Islands and coordinated from a control center in Toulouse, France. This trio is soon to become a quartet, with a fourth station on France's La Reunion Island in the Indian Ocean under development.

- The satellites relay distress messages to these MEOLUTs, which then relay them to local search and rescue authorities.

- The service’s return link message capability was developed as an inherent part of the Galileo system. The messages are relayed to the individual beacons that sent the original distress call by being embedded within Galileo signals broadcast from satellites in their view.

- “The switching on of the return link service was enabled by a thorough test campaign carried out by ESA, with the support of the GSA and CNES,” adds Igor. “We needed to be sure the service remains reliable even with multiple distress calls being replied to at once.”

- A key milestone was a public demonstration of the return link service, performed at the Cospas-Sarsat Joint Committee Meeting in Doha in Qatar last summer.

- “The return link is a joint service of Cospas-Sarsat and Galileo and therefore agreement by Cospas-Sarsat was crucial,” adds Igor.

- “This acceptance was achieved through long discussions led by the European Commission at the Cospas-Sarsat Council last November, supported by plentiful documentation of simulations and test results provided by ESA and CNES.”

Figure 13: GALILEO : Reaching you faster – when every minute matters. Search and Rescue (SAR) operations involve locating and helping people in distress. They can be carried out in a variety of locations including at sea, in mountains or deserts, and in urban areas. With the launch of Initial Services, Galileo will help SAR operators respond to distress signals faster and more effectively while also lowering their own exposure to risk ... (video credit: European Commission)

Note: This 'Mission Status' entry of January 23, 2020 is repeated below at Status of Galileo's SAR (Search & Rescue) Service.

• December 20, 2019: The Galileo satellite navigation system has been providing Initial Services for three years now. Meanwhile Europe’s other satnav system has marked its tenth anniversary: EGNOS has been delivering enhanced positioning to users across our continent, including safety-critical services such as aircraft landings for a growing number of European airports. 30)

- The purpose of EGNOS (European Geostationary Navigation Overlay Service) is to monitor the real-time performance of US GPS satellites, then generate a correction message, containing information on the reliability and accuracy of their positioning data, which are then broadcast via EGNOS’s geostationary satellites to all suitably equipped satnav receivers.

Figure 14: The purpose of EGNOS is to monitor the real-time performance of US GPS satellites, then generate a correction message, containing information on the reliability and accuracy of their positioning data, which are then broadcast via EGNOS’s geostationary satellites to all suitably equipped satnav receivers. EGNOS consists of three geostationary satellites and a Europe-wide ground segment composed of two master control stations, six uplink stations and a network of 40 monitoring stations, all connected and communicating in real time (image credit: ESA)

- The end result is a several-fold increase in positioning accuracy and reliability – which is expressed for aviation users through the notion of its ‘integrity’ – how much can it relied upon at any given time. EGNOS typically allows users in Europe and beyond to determine their position to within 1.5 meters with a very high level of integrity, allowing aircraft to be safely guided down to airport runways.

- EGNOS consists of three geostationary satellites and a Europe-wide ground segment composed of two master control stations, six uplink stations and a network of 40 monitoring stations, all connected and communicating in real time.

- EGNOS was a joint project of ESA, the European Commission and Eurocontrol, the European Organisation for the Safety of Air Navigation. The system’s Open Service began on 1 October 2009, after which EGNOS positioning data became freely available in Europe through satellite signals to anyone equipped with an EGNOS-enabled GPS receiver.

- The system is employed for accuracy and integrity-hungry satnav applications such as precision farming, surveying and transport. EGNOS is, for instance, used within the new eCall system, found in all new cars sold in the EU since March 2018. Whenever a serious accident occurs, eCall automatically passes the incident location to the emergency services, with EGNOS providing added accuracy and integrity.


Figure 15: EGNOS for precision farming. EGNOS is employed for accuracy and integrity-hungry satnav applications such as precision farming, surveying and transport (image credit: GSA)

- But as the European equivalent of the US Wide Area Augmentation System WAAS, EGNOS was primarily designed to serve aviation, specifically for the safety-critical task of guiding down aircraft for landings. This became possible on 2 March 2011, when EGNOS’s ‘Safety-of-Life’ service began to operate.

- Today more than 350 airports - more than half of the total – across Europe employ EGNOS. To do so, they have been certified for what are known as ‘LPV-200 procedures’ allowing pilots to take their aircraft down to 60 m (200 ft) above the ground for a final go/no-go decision on continued landing descent. LPV stands for ‘localizer performance with vertical guidance’.

- This certification allows airports to operate without costly ground-based Instrument Landing System ‘Cat-1’ infrastructure. Major airports hubs such as Paris Charles de Gaulle, Frankfurt and Amsterdam Schiphol employ EGNOS for landing approaches. For smaller regional airports, EGNOS allows them to stay open in all weathers.


Figure 16: Aircraft pilots are making use of EGNOS for what are known as ‘approach with vertical guidance’ procedures at suitably certified European airports. They can provide vertical guidance down to within 60 m altitude of given runways in all weather and conditions, at which point the pilot does the rest (image credit: GSA)

Figure 17: As of April 2018 all new cars will be equipped with eCall technology. In the event of a serious accident, eCall automatically dials 112 - Europe's single emergency number - to provide faster assistance and save lives (video credit: GSA)

- The EGNOS Exploitation Program is managed by the European Global Navigation Satellite System Agency, GSA. ESA retains the role of developing its future System evolution, taking shape as ‘EGNOS V3’ in the coming decade, which will augment signals from both GPS and Galileo satellites for added performance, reliability and extended coverage.

Figure 18: EGNOS augmenting satellite navigation (video credit: ESA)

• July 22, 2019: The Initial Services provided by the European satellite navigation system - Galileo - have been successfully restored. Galileo was affected by a technical incident related to its ground infrastructure. This event led to a temporary interruption of the globally available Galileo navigation and timing services, with the exception of the Galileo Search and Rescue Service. 31)

- The Search and Rescue Service, which is used to locate and assist people in emergency situations, for example, at sea or in remote, mountainous areas, was not affected and remained operational.

- The navigation service impact was caused by a malfunction of some equipment in the Galileo control centers, which generate the system time and calculate orbit predictions; these data are used to produce the navigation messages. The disruption affected various elements at the control centers in Fucino (Italy) and at the DLR site in Oberpfaffenhofen.

- A team of experts from the Galileo Service Operator, led by Spaceopal GmbH, worked as quickly as possible and in close cooperation with the European GNSS Agency (GSA), as well as the industrial ground infrastructure providers together with the European Space Agency (ESA) to rectify the malfunction.

- Due to the high technical complexity of the system and the in-depth analysis of the fault dependencies, these efforts took several days before the resumption of Initial Services on 18 July 2018.

- An independent board of inquiry is now investigating the exact circumstances and root causes that led to the failure. The investigation is being conducted by the EU Commission and the GSA - the authorities that manage the program - in order to continuously improve the system during its initial service phase.

- Galileo has been offering its Initial Service since December 2016. During this initial 'pilot' phase, which precedes the 'full-operational services' phase, Galileo signals are being used also in combination with those from other satellite navigation systems, allowing testing and the detection of potential technical challenges during the commissioning of the system until full deployment and operational capability has been reached.

July 18, 2019: Galileo Initial Services have now been restored. Commercial users can already see signs of recovery of the Galileo navigation and timing services, although some fluctuations may be experienced until further notice. 32)

- The technical incident originated by an equipment malfunction in the Galileo control centers that calculate time and orbit predictions, and which are used to compute the navigation message. The malfunction affected different elements on both centers.

- A team composed of GSA (Global Navigation Satellite Systems Agency) experts, industry, ESA and Commission, worked together 24/7 to address the incident. The team is monitoring the quality of Galileo services to restore Galileo timing and navigation services at their nominal levels.

- We will set an Independent Inquiry Board to identify the root causes of the major incident. This will allow the Commission, as the program manager, together with the EU Agency GSA to draw lessons for the management of an operational system with several millions of users worldwide.

- Galileo provides ‘initial services’ since December 2016. During this initial ‘pilot’ phase preceding the ‘full operational services’ phase, Galileo signals are used in combination with other satellite navigation systems, which allows for the detection of technical issues before the system becomes fully operational. In the full operational phase, Galileo should function independently of other satellite navigation systems.

July 17, 2019: A team of experts from the European GNSS Agency, industry, the European Space Agency and the European Commission is currently implementing and monitoring recovery actions for an incident related to the Galileo ground infrastructure that resulted in a temporary interruption of the Galileo Initial Services. The key objective is to restore the Galileo navigation and timing services for users as soon as possible. 33)

- On 12 July, Galileo initial navigation and timing services were interrupted temporarily. The Galileo Search and Rescue service remains operational.

- Galileo is widely used by most of the commercially available receivers. Multi-constellation GNSS receivers will remain unaffected and compute position and timing using other constellations. Galileo-only receivers will not produce any navigation message.

- As soon as the incident was declared, an Anomaly Review Board was convened and urgent recovery procedures were activated in the affected Galileo infrastructures. Operational teams are working on recovery actions 24/7 to restore the Galileo navigation and timing services as soon as possible.

- Based on the results of the troubleshooting activities, several elements of the ground infrastructure were re-initiated. The progress is being closely monitored; it is too early to confirm an exact service recovery date.

A period for testing and perfecting

- The Galileo satellite navigation system launched its Initial Services in December 2016 and since then it has been providing high quality positioning, navigation and timing services to users worldwide. The aim of this Initial Services phase is to allow for the detection of technical issues before the system becomes fully operational.

- It was precisely to deal with issues of this nature that the EU opted for a progressive roll-out of the Galileo system. The evolution and planned upgrade of the ground infrastructure will reinforce redundancy of the system towards reaching the full operations phase.

- As soon as the outage occurred, the users were informed by the Galileo Service Center through technical notices on 11 and 13 July , as well as a news item on the GSA website on 14 July. Users will be regularly updated, including on the navigation and timing service recovery date, through notifications and information.

- The Galileo team would like to assure users that it is working hard to remedy the situation as soon as possible.

July 14, 2019: Galileo, the EU's satellite navigation system, is currently affected by a technical incident related to its ground infrastructure. The incident has led to a temporary interruption of the Galileo initial navigation and timing services, with the exception of the Galileo Search and Rescue (SAR) service. The SAR service - used for locating and helping people in distress situations for example at sea or mountains - is unaffected and remains operational. 34)

- Galileo provides ‘initial services’ since December 2016. During this initial "pilot" phase preceding the ‘full operational services’ phase, Galileo signals are used in combination with other satellite navigation systems, which allows for the detection of technical issues before the system becomes fully operational.

- Experts are working to restore the situation as soon as possible. An Anomaly Review Board has been immediately set up to analyze the exact root cause and to implement recovery actions.

- As foreseen in case of technical incidents, information Notices to Galileo Users (NAGU) were already published on the Galileo Service Center website:

a) on 11 July 2019:

b) and on 13 July 2019 :


- Users will be informed regularly, including on the service recovery date.

• June 11, 2019: Europe’s students and young researchers were challenged to design a smartphone app to take advantage of Galileo’s dual-frequency signals. Run by ESA in collaboration with the European Global Navigation Satellite Systems Agency – GSA – plus the European Commission with the support of Google, a total of five teams made it to the final of the Galileo smartphone app competition 2019 which took place at ESA’s ESTEC technical heart in the Netherlands on Thursday 18 April. This event was preceded by testing the performance of the competing apps in static, pedestrian and driving use modes. 35)

Figure 19: We are Europe's gateway to space. Our mission is to shape the development of Europe's space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world (video credit: ESA, Uploaded on 11 June 2019)

• March 4, 2019: Global leader in emergency readiness and response, Orolia, is pleased to announce that its McMurdo FastFind 220 and Kannad SafeLink Solo PLBs (Personal Location Beacons) now operate with the Galileo GNSS system. 36)

- Continuing Orolia's innovation and leadership role in Safety Electronics, the PLBs have been upgraded to include Galileo Global Navigation Satellite System (GNSS), the European Union's global satellite constellation.


Figure 20: These are the world's first PLBs utilizing the Galileo satellites' capabilities and are the first of a series of new solutions coming from the EU-funded Helios project, led by Orolia, which has been set up to leverage the power of the new satellite system (image credit: Orolia)

- The multi-constellation receivers work with a wider range of satellites, offering increased global coverage and supporting accelerated rescue missions.

- Location detection is enhanced and can be more precise due to the beacons receiving coordinates from the Galileo satellite network in addition to the tried and tested GPS network. Signals can even be detected in high sided locations, such as canyons.

- "We are thrilled to be launching our upgraded PLBs in the European and US markets," said Chris Loizou, Vice President of Maritime at Orolia.

- "The combination of both Galileo and GPS GNSS capability means that our customers will benefit from coverage that spans from the North to the South Pole. We work tirelessly to push the boundaries of product innovation and, ultimately, to give people the best chance of being rescued in an emergency situation."

- The McMurdo FastFind and Kannad SafeLink PLBs are part of Orolia's comprehensive search and rescue ecosystem and join the McMurdo SmartFind G8 and Kannad SafePro series EPIRBs (Emergency Position Indicating Radio Beacons) as the first Galileo capable rescue beacons.

- As the world's only provider of an end-to-end search and rescue ecosystem - including distress beacons, satellite ground stations, mission control and rescue coordination systems, and rescue response products - Orolia's McMurdo brand uniquely builds, integrates and tests products as part of a live search and rescue system.

- This ensures greater cohesion between distress signal transmission and reception so that beacon owners can feel confident that their signals will get to search and rescue authorities quickly.

• February 7, 2019: The latest four Galileo satellites, launched on 25 July 2018, have been given the green light to begin working alongside the rest of Europe’s satellite navigation fleet, giving a further boost to worldwide Galileo service quality. 37)

- Galileo has grown to become Europe’s single largest satellite constellation, built up over 10 launches over the course of this decade. The first of seven double-satellite Soyuz launches took place in 2011, with three sets of four-satellite Ariane-5 launches during the last three years. — The latest quartet of Galileo satellites were launched together by Ariane 5 on 25 July, bringing the number of satellites in orbit to 26.


Figure 21: Europe's Galileo navigation satellites orbit 23 222 km above Earth to provide positioning, navigation and timing information all across the globe (image credit: GSA)

• December 17, 2018: Use Europe’s satellite navigation system to seek treasure in virtual mazes or ‘see’ Galileos as they cross the sky above you: two new Android smartphone apps based on Galileo are now available for general download, the results of a competition by ESA trainees. 38)

- With newer Android smartphones you can access the raw signal measurements used to compute position, opening the door to the development of applications where the user can indeed select which satellites to use. So ESA ran an internal competition for its trainees to develop an app capable of making positioning fixes using only Galileo satellites.

- The Callisto – Galileo’s Spaceship app uses Galileo satnav signals to run a virtual maze game based on walking through a real world location.

- Looking down on Earth as if from a spaceship, players use a standard Google map display to traverse a rectangular area filled with randomly generated obstacles and collectibles. You play against the clock to grab prizes, with points deducted for running into virtual barriers.

- “It was fun for us to develop as a team, but one of the main purposes behind it was to spread the message about Galileo,” explains ESA young graduate trainee Peter Vanik, part of the five-person ‘Chocolateam’ that created the app.

- “Users can use signals from the Galileo constellation by itself, GPS by itself or GPS and Galileo in combination to get a sense of the different accuracy levels – the combination of constellations will work best, because that way the most satellites are available for use.”

- The team used online tutorials and YouTube videos to learn how to develop for Android, with their satnav backend derived from GNSSCompare – the winning app from ESA’s internal competition, offering to turn a smartphone in a ‘research lab in your pocket’.

- None of us are satnav specialists, so we played off not knowing all the nitty-gritty as an advantage rather than a weakness, in terms of targeting the general public,” adds Matej Poliaček of the Callisto team.

- “The idea of a game came up early on, with a satnav-based gameplay loop,” says the team’s Cedric Ia. “Then Lionel Garcia, our designer, had the idea of making it spaceship-based, and that was where the design for our user interface came from.”

- “Working together with GNSSCompare was a way to combine the best of both worlds,” explains team member Emilie Udnæs. “They’re stronger on the GNSS side of things while we took a user-centered approach.

- The Callisto app was designed on and for a Galaxy S8 smartphone, but the team is expanding the app to serve as many different phones as possible, to target a general public audience.

- Another app developed through the competition is also available for download from Google Play. GalileoPVT was created by ESA navigation engineer Paola Crosta and electrical engineer Tim Watterton to serve as a benchmark to judge competition entries. The duo went on to finalize and publish it.

- “GalileoPVT allows users to compare position fixes calculated from Galileo and GPS signals, and also to visualize Galileo satellites and signals live in the sky using augmented reality,” explains Tim.

- “The raw signals can be saved for post-processing by users. There’s also a fun hidden game, where the player has to maneuver their Galileo satellite to avoid increasingly bizarre items of space debris, aided by received Galileo signals that boost their satellite’s health.”

- “GalileoPVT can also be installed on devices that do not support Galileo signals. Although the user will not be able to receive the live Galileo signals or calculate a fix with Galileo, they can still see the predicted satellite positions on the augmented reality view, and play the hidden game.”

- A current list of smartphones that support Galileo can be found here.


Figure 22: The GalileoPVT app allows users to compare position fixes calculated from Galileo and GPS signals, and also to visualize Galileo satellites and signals live in the sky using augmented reality. It also features a hidden game (image credit: ESA)


Figure 23: An augmented reality view of a Galileo satellite above Cape Town, South Africa. Space engineer Frank Bagiana took a smartphone equipped with the GalileoPVT app during his holiday to Africa to take some pictures of Europe's navigation satellites. Satellites in green are contributing to the receiver's positioning solution (image credit: ESA)

• December 4, 2018: Galileo satellites measure Einsteinian Time Dilation. Europe’s Galileo satellite navigation system – already serving users globally – has now provided a historic service to the physics community worldwide, enabling the most accurate measurement ever made of how shifts in gravity alter the passing of time, a key element of Einstein’s Theory of General Relativity. 39)

Two European fundamental physics teams working in parallel have independently achieved about a fivefold improvement in measuring accuracy of the gravity-driven time dilation effect known as ‘gravitational redshift’.

The prestigious Physical Review Letters journal has just published the independent results obtained from both consortiums, gathered from more than a thousand days of data obtained from the pair of Galileo satellites in elongated orbits. 40)


Figure 24: The relativistic eccentricity of Galileo satellites 5 and 6 reaches a peak amplitude of approximately 370 nanoseconds (billionths of a second), driven by the shifting altitude, and hence changing gravity levels, of their elliptical orbits around Earth. A periodic modulation of this size is clearly discernible, given the relative frequency stability of the PHM (Passive Hydrogen Maser) atomic clocks aboard the satellites (image credit: ESA)

It is most satisfying for ESA to see that our original expectation that such results might be theoretically possible have now been borne out in practical terms, providing the first reported improvement of the gravitational redshift test for more than 40 years,” comments Javier Ventura-Traveset, Head of ESA’s Galileo Navigation Science Office.

“These extraordinary results have been made possible thanks to the unique features of the Galileo satellites, notably the very high stabilities of their onboard atomic clocks, the accuracies attainable in their orbit determination and the presence of laser-retroreflectors, which allow for the performance of independent and very precise orbit measurements from the ground, key to disentangle clock and orbit errors.”


Figure 25: Galileo satellites 5 and 6 were delivered into faulty elongated orbits by a faulty Soyuz upper stage during their launch in 2014. This left them unable to view the entire Earth disc during the low point or perigee of their orbits, rendering their navigation payloads unusable, because they use an Earth sensor to center their signal beams. Subsequent orbital maneuvers succeeded in making their orbits more circular and their navigation payloads usable because they retained views of the entire Earth disc through each orbit. However their orbits remain elliptical compared to the rest of the Galileo constellation. Bottom view from orbital plane of nominal orbit (in blue) and injected orbit (in green) for the pair (image credit: ESA)

These parallel research activities, known as GREAT (Galileo gravitational Redshift Experiment with eccentric sATellites), were led respectively, by the SYRTE Observatoire de Paris in France and Germany’s ZARM Center of Applied Space Technology and Microgravity in Bremen, coordinated by ESA’s Galileo Navigation Science Office and supported through its Basic Activities.

Welcome results from an unhappy accident

These findings are the happy outcome of an unhappy accident: back in 2014 Galileo satellites 5 and 6 were stranded in incorrect orbits by a malfunctioning Soyuz upper stage, blocking their use for navigation. ESA flight controllers moved into action, performing a daring salvage in space to raise the low points of the satellites’ orbits and make them more circular.

Once the satellites achieved views of the whole Earth disc their antennas could be locked on their homeworld and their navigation payloads could indeed be switched on. The satellites are today in use as part of Galileo search and rescue services while their integration as part of nominal Galileo operations is currently under final assessment by ESA and the European Commission.

However, their orbits remain elliptical, with each satellite climbing and falling some 8500 km twice per day. It was these regular shifts in height, and therefore gravity levels, which made the satellites so valuable to the research teams.


Figure 26: Albert Einstein lecturing in Vienna in 1921 (image credit: Public domain)

Reenacting Einstein’s prediction

Albert Einstein predicted a century ago that time would pass more slowly close to a massive object, a finding that has since been verified experimentally several times – most significantly in 1976 when a hydrogen maser atomic clock on the Gravity Probe-A suborbital rocket was launched 10,000 km into space, confirming Einstein’s prediction to within 140 parts per million.

In fact, atomic clocks aboard navigation satellites must already take into account the fact that they run faster up in orbit than down on the ground – amounting to a few tenths of a microsecond per day, which would result in navigation errors of around 10 km daily, if uncorrected.


Figure 27: The Gravity Probe A payload of 1976, flown in a highly elliptic single orbit to measure the ‘gravitational redshift’ of Einstein’s Theory of General Relativity more accurately than ever before, seen with its designers Robert Vessot and Martin Levine of the Smithsonian Astrophysical Observatory. The experiment compared a hydrogen maser clock on Earth with its replica in space as it ascended to about 10,000 km, and confirmed theoretical expectations to an accuracy of 0.02% (


Figure 28: Periodic modulation of the gravitational redshift for one day's orbit of the eccentrically-orbiting Galileo satellites (image credit: ESA)

The two teams relied upon the stable timekeeping of the PHM (Passive Hydrogen Maser) clocks aboard each Galileo – stable to one second in three million years – and kept from drifting by the worldwide Galileo ground segment.

“The fact that the Galileo satellites carry passive hydrogen maser clocks, was essential for the attainable accuracy of these tests,” noted Sven Hermann at the University of Bremen’s ZARM Center of Applied Space Technology and Microgravity. “While every Galileo satellite carries two rubidium and two hydrogen maser clocks, only one of them is the active transmission clock. During our period of observation, we focus then on the periods of time when the satellites were transmitting with PHM clocks and assess the quality of these precious data very carefully. Ongoing improvements in the processing and in particular in the modelling of the clocks, might lead to tightened results in the future.”

Refining the results

A key challenge over three years of work was to refine the gravitational redshift measurements by eliminating systematic effects such as clock error and orbital drift due to factors such as Earth’s equatorial bulge, the influence of Earth’s magnetic field, temperature variations and even the subtle but persistent push of sunlight itself, known as ‘solar radiation pressure’.

“Careful and conservative modelling and control of these systematic errors has been essential, with stabilities down to four picoseconds over the 13 hours orbital period of the satellites; this is four millionth of one millionth of a second,” Pacôme Delva of SYRTE Observatoire de Paris. “This required the support of many experts, with notably the expertise of ESA thanks to their knowledge of the Galileo system.”


Figure 29: Passive hydrogen maser atomic clock of the type flown on Galileo, accurate to one second in three million years (image credit: ESA)

Precise satellite tracking was enabled by the International Laser Ranging Service, shining lasers up to the Galileos’ retro-reflectors for centimeter-scale orbital checks.

Major support was also received from the Navigation Support Office based at ESA's ESOC operations center in Germany, whose experts generated the reference stable clock and orbit products for the two Galileo eccentric satellites and also determined the residual errors of the orbits after the laser measurements.


Figure 30: Satellite laser ranging station at Potsdam GFZ in Germany, part of a worldwide network known as the International Laser Ranging Service (image credit: DLR)

• November 9, 2018: ESA is setting up a new GSSC (GNSS Science Support Center) facility at ESA's ESAC (European Space Astronomy Center) near Madrid, Spain. Run by ESA’s Galileo Science Office, the GSSC integrates IT and satnav infrastructure to deliver advanced data processing services to the scientific community. 41)

- Precisely timed to a few billionths of a second and highly stable, satnav signals can be used as a point of reference for many scientific sectors, including Earth and atmospheric sciences, astronomy, highly precise timing ‘metrology’ as well as the study of relativity and other fundamental physics topics.


Figure 31: Photo of ESA's GSSC facility at ESAC, near Madrid (image credit: ESA)

- Current satnav infrastructure plans worldwide should see more than 120 satnav satellites in orbit in coming years. This number includes Europe’s own Galileo constellation – offering unique features such as its highly stable passive hydrogen maser atomic clocks, multiple transmission frequencies, robust modulation, wide bandwidth and onboard laser retro-reflectors, which permit exact pinpointing of the satellites’ position in space down to a few tens of centimeters.

- “The potential of satnav for science has been recognized for a long time,” explains Javier Ventura-Traveset, Head of ESA’s Galileo Science Office. “The Galileo Science Office was set up in 2016 as a joint initiative between ESA’s Science and Navigation Directorates, coordinating scientific opportunities through interaction with the scientific community and the independent GNSS Science Advisory Committee.

- “The opening of the new center is the next step. It is ESA’s concrete answer to the need expressed by the scientific community for a ‘one-stop-shop’ to offer researchers long-term GNSS data, products information, results of scientific experiments, plus services to enhance GNSS scientific research and collaboration.

- “The future evolution of the center will be driven by the interaction and feedback received from the scientific community, maximizing synergies with other GNSS data service providers from other institutions and research organization.”

- Among the activities to be supported by the new GSSC are big data processing of large amounts of satnav data, crowdsourcing as a means of weather monitoring and a scientific assessment of satnav performance in Antarctica.

- It also supports the continuing measurements of general relativity using Galileo satellites 5 and 6 and serves as a global data center for the International GNSS Service. The long-established Navipedia website, giving technical information on satnav, is also hosted by the GSCC.

- One enthusiastic early adopter is ESA’s Navigation Support Office, based at ESA’s ESOC mission control center in Darmstadt, Germany, lending support to mission teams making use of satnav to steer satellites.

- “The GSSC is a welcome addition to ESA’s activities in the science of satellite navigation,” says Werner Enderle, heading ESOC’s Navigation Support Office. “The GSSC already hosts GNSS products generated by the team at ESOC, including observations from our worldwide EGON GNSS Observation Network and precise satellite orbits generated by their state-of-the-art software. Our two teams look forward to this collaboration continuing for the benefit of ESA and the scientific community.”

- The GSSC will roll out access to data, products and services over the coming months.

• October 18, 2018: Europe’s 26 navigation satellites in orbit are providing Galileo Initial Services – available to users around the globe since 2016 – and a new ESA contract signing means these services will be delivered on a more accurate basis and more securely than ever. 42)

- ESA has awarded a new framework contract and two new work orders to Thales Alenia Space in France, to upgrade the Galileo Mission Segment – that element of the worldwide Galileo ground segment dedicated to delivering navigation services – and the Galileo Security Monitoring Center (GSMC) near Paris, as well as to implement 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 17 October 2018 at ESA/ESTEC 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,” the ESA Director commented. “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.

- “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 program.”

- 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.

- 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. Last year 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 (see Figure 66).


Figure 32: Surveyor using a GNSS device to map urban assets using Galileo and EGNOS (image credit: GSA)

• October 2018: Galileo has made significant progress in recent years: twenty-six Galileo satellites are now orbiting the Earth, a significant part of the supporting ground station infrastructure has been deployed, and the European GSA (GNSS Supervisory Agency) has assumed the role of the Galileo Service Provider. 43)

- With the Declaration of Galileo Initial Services on the 15th of December 2016, the transition of Galileo from the testing and deployment phase to a system in service has started, and Galileo is now ready to be used. During this Initial Services provision phase, deployment activities towards Full Operational Capability continues in parallel. To support this service phase, the GSA has established a new service facility called the GRC (Galileo Reference Center) in Noordwijk, the Netherlands.

• September 21, 2018: Since the launch of Initial Services in December 2016, Galileo has been providing more and more users with global positioning, navigation and timing information. Behind this increase in use is the wide array of Galileo-enabled devices and services that have entered the market – including over 60 smartphone models in the past two years. Furthermore, as of April, all new types of cars sold in the EU must be equipped with Galileo as required by the eCall regulation. Galileo is also being increasingly used in drones to ensure smooth navigation and in Search and Rescue operations to save lives. 44)

- With this increased interest in Galileo, both the general public and industry want to know what devices are Galileo-capable.

- As new devices are constantly being added to the list, the GSA launched an enhanced version of its popular website. The site allows users to easily search and keep track of Galileo-enabled devices as they become available.

- The enhanced site includes new categories covering applications in the timing, Internet of Things (IoT) and space application segments. Furthermore, other categories, such as aviation, emergency services and agriculture, now include a number of sub-categories. For example, within the aviation segment, users can narrow their search to Galileo-enabled devices and applications for avionics, airports and Unmanned Aerial Vehicles (UAVs). Flight operators can even search per their particular aircraft, whether that be a business jet, a helicopter or a commercial airliner.

- “We are proud to see how quickly Galileo is being embraced by European citizens and businesses,” says GSA Executive Director Carlo des Dorides. “The enhanced UseGalileo site and its many segment-specific search functions is another example of how we keep the user at the center of European GNSS.”

• September 18, 2018: An app that lets your smartphone work directly with Galileo and check performance from raw satellite signal measurements is now available for download from the Google Play Store. 45)

- Developed by ESA trainees in their spare time, the GNSS Compare app was the winner of an internal ESA competition this summer.

- “GNSS Compare is an open source tool making the lives of satnav developers and researchers easier,” explains ESA young graduate trainee Mateusz Kraiński from Poland, who led the four-person ‘Galfins’ development team. “We think of it as a research lab in your pocket.”

- Mateusz explains that the new app shows details of which satellites your phone is using to perform its positioning, velocity and timing (PVT) calculations, along with their relative signal strength.

- “You can also choose between Galileo-only, GPS-only or Galileo plus GPS, as well as altering processing settings, to see how the positioning performance changes as a result – or else put your own prototype processing algorithms to the test. - In the past you would have to do this with expensive receivers or software-defined radios, but GNSS Compare lets users perform checks in a very simple way, using just the hardware in their pocket. It also has an educational aspect, because users can really ‘look under the hood’ and see for themselves how the PVT process works in practice.”

- The receiver chipsets inside smartphones compute positioning using multiple satellite constellations without regard for which satellites’ signals are used, giving results but with no insight into how they are calculated, or the opportunity to choose which satellites to employ.

- The GNSS Compare app was made possible by the fact that newer Android smartphones can access the raw satellite signal measurements used to compute positioning.


Figure 33: The winning Galfins team of ESA's Galileo smartphone app flanked by members of the other two teams of ESA trainees, ‘Chocolateam’ and ‘Team 5G’, at the end of the competition's final presentation at ESA's ESTEC technical center on 31 May 2018. At the far left is Riccardo De Gaudenzi, head of ESA's Radio Frequency Systems and Payloads Office; to the far right is Javier Benedicto, ESA’s Galileo program manager (image credit: ESA–G. Porter, CC BY-SA 3.0 IGO)

- “Last year, we took advantage of this change to introduce our inaugural Galileo Smartphone App Competition,” says Nityaporn Sirikan of ESA’s Navigation Directorate. We challenged ESA trainees to develop an app to perform satnav fixes using solely Galileo satellites,” she explains. “Three teams developed apps in their spare time, each one targeting different user groups. They were judged by a jury of experts from the European Global Navigation Satellite Systems Agency – GSA – and Google as well as ESA. The response was very positive, and we are now planning a second competition.”

- As a trainee at ESA/ESTEC in the Netherlands, Mateusz’s dayjob has been focused on the European Robotic Arm, destined for the International Space Station. His fellow Galfins team trainees are Germany’s Mareike Burba working on Earth observation, Romanian Sebastian Ciuban – the team’s sole Navigation specialist – and Polish-born Dominika Perz, focused on satellite guidance, navigation and control.

- Their prize for winning was attending the ESA and European Commission-sponsored International Summer School on Global Navigation Satellite Systems in Austria.

• July 13, 2018: Europe’s next Galileo satellites have been put in place on top of the Ariane 5 launcher due to lift them from Europe’s Spaceport in Kourou, French Guiana on Wednesday 25 July (Figure 34). 46)

- “In preparation for their launch the four satellites were switched off, apart from their battery charging line and another maintenance power line to their PHM (Passive Hydrogen Maser) atomic clocks,” reports Jean Verniolle, ESA’s Galileo mission director for this launch.

- “Next Galileo satellites 23–26 were integrated one by one on four successive days onto the Galileo dispenser that will hold them securely in place for launch, and to form what we call the launch ‘stack’.”


Figure 34: Galileo quartet placed atop Ariane 5: Galileo satellites 23-26 were lifted to the top of their Ariane 5 launcher inside the BAF ‘Bâtiment d’Assemblage’ building on Wednesday 11 July, ahead of their Wednesday 25 July 2018 launch (image credit: ESA/CNES/Arianespace/Optique Video du CSG - P Baudon)

• July 11, 2018: An augmented reality view of Galileo satellites in the sky close to ESA’s technical center in the Netherlands. It comes from a Galileo-focused satnav app for Android smartphones, developed by ESA engineers. 47)

- ESA ran an internal competition for its trainees to develop an app capable of making positioning fixes using only Galileo satellites.

- “As part of our support for the competition, we developed our own app on a voluntary basis to serve as a benchmark,” explains Paolo Crosta of ESA’s Radio Navigation Systems and Technology section. “We included this augmented reality view, so users can ‘see’ the satellites their smartphone is using as they hold it up to the sky.”

- The positioning calculations and assistance data functions for the app were developed by Paolo, with telecom engineer Tim Watterton contributing the main structure of the app, together with how it looks and its user interface.

- Tim adds: “The satellites are overlaid in real time on the camera view in their predicted positions in the sky, based on ‘ephemeris’ information, assistance data that describes the current satellite orbits with high precision.

- “When a signal is being received, the satellite is shown in green, overlaying the predicted position. The satellite shown in red is one of the two placed in elongated orbits, but these satellites are expected to be used soon in the operational constellation. Satellites colored orange are transmitting, but the signal is not detected, which may be due to obstruction by terrain or buildings.”

- Panning the phone around to position the crosshair over a green colored satellite adds additional information about it, such as its signal status, ‘pseudo-range’ (the uncorrected distance the signal has travelled to reach the receiver) plus the satellite’s manufacturer, launch date among other items. The reference app is now being tested with the hope of making it publicly available on the Android Play Store. The trainees are also testing their own apps following the competition with the goal of releasing them.

- There are 22 Galileo satellites in orbit, with four more satellites set for launch on 25 July.


Figure 35: Galileo satellites viewed in smartphone app (image credit: ESA)

• July 2, 2018: Europe’s satellite navigation system Galileo is already in use worldwide, usable by itself or in combination with the US Global Positioning System (GPS). Now a combined Galileo–GPS positioning fix has been achieved in space – aboard the International Space Station – through an ESA–NASA collaboration. 48)

- Low-Earth orbiting satellites routinely make use of satellite navigation signals to pinpoint their position in space and allow their paths through space to be fixed with extremely high accuracy, known as ‘precise orbit determination’.

- So far, such positioning has mainly been performed using GPS, but this new test proves it can also be achieved on a dual-constellation basis with both GPS and Galileo – as well as through the sole use of Galileo.

- The experiment is based on the use of a re-configurable NASA receiver called the Space Communications and Navigation Testbed, SCaN, attached to the exterior of the ISS.

- ESA’s Navigation Support Office, based at its ESOC control center in Darmstadt, Germany, teamed up with its Radio Navigation Systems and Technology team, located at its ESTEC technical center in Noordwijk, the Netherlands, and Italy’s NASCOM company to develop the techniques, software and firmware required for the experiment, which was passed to NASA’s Glenn Research Center in Ohio for upload to the receiver.

- “SCaN is a versatile software-defined radio receiver in space for both telecommunications and navigation testing, delivered to the Station back in 2012,” explains ESA radio-navigation engineer Pietro Giordano. “It made it possible, with suitable modifications, to demonstrate combined GPS-Galileo positioning determination of the ISS.”

- The algorithm developed for the SCaN Testbed had to take account of the high dynamics involved, and resulting Doppler shifting of signals: not only are the Galileo and GPS satellites moving at orbital velocity, so is the ISS itself. Orbital information of all the satellites in both constellations was included in the algorithm, allowing SCaN to make a ‘warm start’ – to search out signals in the correct segments of the sky.


Figure 36: SCaN Testbed on ISS: A re-configurable NASA receiver SCaN (Space Communications and Navigation Testbed) is attached to the exterior of the ISS. In April 2018 the chest-sized SCaN, seen left of center with an antenna on top, was used to make the first combined Galileo-GPS positioning fix in orbit (image credit: NASA)

- “Dual constellation fixes offer many advantages for space, providing extremely robust and high-precision positioning,” adds Pietro. “More signals become available overall, and the quality of the Galileo Open service and modernized GPS signals are extremely good.”

- Werner Enderle, overseeing the project at the Navigation Support Office notes: “These excellent first results, coming out of great teamwork within ESA, collaboration with industry and with our NASA partners, mark just the beginning of our project data analysis. Many other exciting results are expected related to signal aspects, precise orbit determination and positioning based on optimized algorithms.”

- James J. Miller, GPS Sr. Technologist within the SCaN program office at NASA Headquarters, comments: “We’ve been promoting interoperability of GPS and Galileo through a number of activities within the United Nation’s International Committee on Global Navigation Satellite Systems (GNSS). In particular, NASA, with ESA and other national space agencies, has been identifying benefits to be gained for high altitude users in the multi-GNSS Space Service Volume under development. By further demonstrating multi-GNSS capabilities in low Earth orbit, the drive for additional utility at geostationary orbit and beyond is only strengthened”.

- Europe’s Galileo system began Initial Services for users in December 2016, and there are 22 Galileo satellites in orbit. The launch of four more Galileo satellites by Ariane 5 is scheduled for 25 July, bringing the constellation to 24 satellites plus two orbital spares.

- ESA is developing dual Galileo-GPS receivers for the next generation of Earth-observing Sentinel satellites. The more precise the orbit determination, the more accurate the environmental data that can be returned to Earth.

- Combined use of Galileo and GPS signals on an interoperable basis for positioning and precise orbit determination should bring significant advantages for space users in particular, set to provide a seamless navigation capability from low to high Earth orbits – and potentially beyond.

- Paul Verhoef, ESA’s Director of Navigation, states: “This shows the versatility of the Galileo system and the use of the system for scientific and other purposes, way beyond traditional navigation services. We have also started work to determine whether we can use Galileo, in combination with GPS and other systems, for navigation to the Moon.”

• June 7, 2018: ESA microwave engineers took apart an entire Galileo satellite to reassemble its navigation payload on a laboratory test bench to run it as though it were in orbit – available to investigate the lifetime performance of its component parts, recreate satellite anomalies, and test candidate technologies for Galileo’s future evolution. 49)

- Located in the cleanroom environment of the Galileo Payload Laboratory – part of ESA’s Microwave Lab based at its ESTEC technical center in the Netherlands – the new Galileo IOV Testbed Facility was inaugurated this week with a ceremony attended by Paul Verhoef, ESA Director of Navigation and Franco Ongaro, ESA Director of Technology, Engineering and Quality.

- Paul Verhoef congratulated the team and underlined the importance of ESA having these capabilities: ”Such a navigation payload laboratory does not exist in industry. We foresee the testing and validation a number of very innovative ideas for the next series of Galileo satellites, before entering into discussions with industry in the context of the procurement of the Galileo Transition Satellites that has recently begun. This shows the added value of ESA as the design agent and system engineer of the Galileo system.”

- “Our Lab has always been very responsive to the testing needs of the Navigation Directorate,’ comments microwave engineer César Miquel España. Now this unique facility allows performance of end-to-end testing of a Galileo payload as representatively as possible, using actual Galileo hardware. We can also support investigations of any problems in orbit or plug in future payload hardware as needed. And because each item of equipment is separately temperature controlled we can see how environmental changes affect their performance.”

- The Testbed began as an ‘engineering model’ of a first-generation Galileo In-Orbit Validation (IOV) satellite, built by Thales Alenia Space in Italy for ground-based testing. It was delivered to ESTEC in August 2015, along with four truckloads of ground support equipment and other hardware.

- That began a long three-year odyssey to first take the satellite apart, then put it back together – akin at times to space archeology, since the satellite had been designed more than 15 years ago.


Figure 37: Photo of ESA/ESTEC's new Galileo payload test facility showing the elements of a Galileo satellite (image credit: ESA, Cesar Miquel Espana)

- “We found lots of documentation on how to integrate the satellite, but nothing on how to take it apart,” adds technician Gearóid Loughnane. “We had to dismantle it very carefully over several weeks to remove the smaller items safely and take out the electrical harness, which ended up as a big spaghetti pile on the floor.”

- The next step was to extricate the navigation payload from the satellite platform, and then begin to lay it out to connect it up again. A parallel effort tracked down supporting software from the companies involved, to be able to operate the payload once it was complete, as if it is orbiting in space.

- Valuable help came from Surrey Satellite Technology Limited in the UK, Dutch aerospace company Terma that developed Galileo software, and Rovsing in Denmark, supplying ground support equipment.

- “A big challenge was tailoring the spacecraft control and monitoring system to work only with the payload units while having to emulate the platform equipment” comments technician Andrew Allstaff.

- Comprising equipment produced by companies in seven separate European companies, the Testbed generates navigation signals using actually atomic clocks co-located in the lab, which are then upconverted, amplified and filtered as if for transmission down to Earth.

- The idea came from a GIOVE Payload Testbed already in the Lab, which simulates the performance of a test satellite that prepared the way for Galileo. As a next step the team hopes they can one day produce a Galileo ‘Full Operational Capability’ Payload Testbed – the current follow-on to the first-generation IOV satellites.

• June 5, 2018: Galileo satellites 25 and 26 have landed at Europe’s Spaceport in Kourou, French Guiana, joining their two predecessors ahead of their 25 July launch by Ariane 5. 50)

- The quartet of Galileo satellites, numbers 23, 24, 25 and 26 will be launched together on a customized Ariane 5 on 25 July – designated Flight VA244 by Arianespace. The vehicle will deploy its satellite passengers at a targeted orbital altitude of 23,222 km.

• May 9, 2018: The next two satellites in Europe’s Galileo satellite navigation system have arrived at Europe’s Spaceport in Kourou, French Guiana, ahead of their planned launch from the jungle space base in July. Galileo satellites 23 and 24 left Luxembourg Airport on a Boeing 747 cargo jet on the morning of 4 May, arriving at Cayenne – Félix Eboué Airport in French Guiana that evening. 51)

- They were then unloaded, still in their protective air-conditioned containers, and transported by truck to the cleanroom environment of the preparation building within Europe’s Spaceport.

- This pair will be launched along with another two Galileo satellites, which are due to be transported to French Guiana later this month.

• March 15, 2018: Indra Sistemas of Madrid, Spain, has been awarded a contract for implementing four new ULS (Uplink Stations), thus expanding the ground segment of the European global positioning system, Galileo. Awarded by the company Thales Alenia Space (France), this contract also includes maintenance and upgrades for all Uplink stations. 52) 53)

- The Uplink Stations provide satellites with messages containing navigation data generated after verifying their onboard clocks and orbital positioning, which could be affected by solar winds or the gravitational fields of the Earth or Moon.

- Satellites can use these messages to send precise data to the growing number of mobile devices and positioning systems used by companies and individuals. A deviation in the data sent by merely one billionth of a second would amount to a positioning error of 30 cm on Earth. The data messages that these stations send therefore have a vital role in achieving the precision of the entire system.

- In addition to deploying the entire ULS network, Indra has also implemented all the Telemetry, Tracking and Control (TT&C) stations managing Galileo satellites. These stations are distributed at different points around the globe to ensure that satellites remain in permanent contact with at least one at all times for monitoring their positions and sending control orders.

- Indra engineers have implemented them in places such as Kourou (French Guiana), Kiruna (Sweden), Noumea (New Caledonia), Reunion Island (overseas department of France), Svalbard (Norway) and Papeete (French Polynesia).

- Galileo provides critical services that depend on the perfect operation of this system, including search and rescue operations at sea, which was one of the first services activated when the system was commissioned back in December 2016. Additional capabilities have gradually been included to address situations related to emergency and crisis response and management, shipping, navigation, construction, etc.

- Together with the control centers in Germany and Italy, the ULS and TT&C stations deployed by Indra are the key components in Galileo's ground segment.

- One of the planet's most precise systems: In addition to deploying these stations, Indra has also worked on the supply and deployment of Time and Geodetic Validation Facilities (TGVF) within the framework of the Galileo project. This component independently runs performance assessments on the Galileo system to ensure that it supplies correct information. The company handles this element of the Mission Center in Fucino (Italy). Indra also developed the mainframe computer's processing systems for the sensor station network (GSS) supporting the center.

- Indra is also co-leading the development of the EU's GNSS Service Center, which will be Galileo's point of contact with the end users of the system's open and commercial services, providing them with expertise, knowledge, and support. The center is set to be based at the National Institute of Aerospace Technologies (INTA) facilities at Torrejón de Ardoz (Madrid).

- To date, Galileo is the most ambitious space initiative promoted by the European Commission and the European Space Agency. Indra has participated in developing the entire ground infrastructure since the project's early phases.

• February 1, 2018: The Galileo satellite navigation system, Europe's rival to the United States' GPS, has nearly 100 million users after its first year of operation, the French space agency CNES said on 1 Feb. 2018. 54)

- The system, seen as strategically important to Europe, went live in December 2016, having taken 17 years at more than triple the original budget to get there.

- Initial services offered only a weak signal, and some of the atomic timekeepers on the satellites failed while two satellites were placed in the wrong orbit.

- But additional satellites have been added since, and by 2020 Galileo is supposed to offer much greater accuracy than GPS, pinpointing a location to within a meter, instead of several meters.

- Apple's latest iPhones as well as Samsung devices are Galileo-compatible, as are cars and other connected objects.

- CNES said airlines including Air France and Easyjet also plan to adopt the system.

- The Galileo program is funded and owned by the European Union, which no longer wants to rely on the military-owned competitors—GPS and Russia's GLONASS.

- Starting this year all new cars sold in Europe will be fitted with Galileo for navigation and emergency calls.

- Clients of a paying service will be able to receive even more accurate readings of down to just centimeters, aiding search-and-rescue operations and improving the safety of driverless cars.

• January 29, 2018: With Europe’s Galileo satellite navigation system only one launch away from full global coverage, representatives of European industry gathered at ESA/ESTEC in the Netherlands to discuss the transition towards the future Galileo Second Generation. 55)

- Galileo Initial Services began on 15 December 2016, while the constellation in orbit has grown to 22 satellites. An Ariane 5 launch later this year of another quartet will bring the constellation to the point of completion with 24 satellites, plus two orbital spares.

- A steady stream of orbital spares, ready to replace satellites reaching the end of their operational lives, is necessary to ensure Galileo continues operating seamlessly. A further 12 satellites were therefore ordered from industry in June 2017.

- Looking further ahead, with the aim of keeping Galileo services as a permanent part of the European and global landscape, a replacement set of Galileo satellites will be required post-2020, serving as transition to a future generation.

- The Galileo Second Generation is foreseen to offer improved performance and added features. This is why the EC (European Commission) has decided on a Transition Program, with ESA in charge of its technical definition and implementation.

- Together with the EC and the European Global Navigation Satellite System Agency, ESA invited leading European space companies to its technical center in Noordwijk to discuss Galileo’s future and present short-term plans in relation to this transition program.

- Having started with the ESA European Global Navigation Satellite System Evolutions Program (EGEP), the system and technology development of the Galileo Second Generation is being supported through the EU’s GNSS and Horizon 2020 HSNAV Programs, with ESA being delegated its technical definition and management of its related implementation.

- Eleven Phase-B contracts were signed at the meeting for the Design Phase for both the Galileo Second Generation and the Transition Program, complementing the more than 50 technology contracts signed in 2017 to prepare for Galileo’s future.

- In recent years, innovations have been analyzed and predevelopments performed in various technology fields (system, ground, space, receiver technologies) in order to assess their suitability for future Galileo activities, while ensuring backward compatibility and continuity of Galileo Services.

- In the next eight months, all major public and private stakeholders will be involved in the detailed assessment of the different evolution scenarios and associated technologies, in order to come to decisions on the Transition Program baseline for the evolution towards Galileo Second Generation.


Figure 38: Photo of the Navigation Days audience at ESA/ESTEC (image credit: ESA)

• July 4, 2017: Investigators have uncovered the problems behind the failure of atomic clocks onboard satellites belonging to the beleaguered Galileo satnav system, the European Commission said on July 2. 56)

- For months, the European Space Agency — which runs the program — has been investigating the reasons behind failing clocks onboard some of the 18 navigation satellites it has launched for Galileo, Europe's alternative to America's GPS system.

- Each Galileo satellite has four ultra-accurate atomic timekeepers, two that use rubidium and two hydrogen maser. But a satellite needs just one working clock for the satnav to work — the rest are spares.

- Three rubidium and six hydrogen maser clocks were not working, with one satellite sporting two failed timekeepers.

- "The main causes of the malfunctions have been identified and measures have been put in place to reduce the possibility of further malfunctions of the satellites already in space," commission spokeswoman Lucia Caudet said.

- ESA found after an investigation that its rubidium clocks had a faulty component that could cause a short circuit, according to European sources. The investigation also found that operations involving hydrogen maser clocks need to be controlled and closely monitored, the same sources said.

- The agency has taken measures to correct both sets of problems, the sources added, with the agency set to replace the faulty component in rubidium clocks on satellites not yet in orbit and improve hydrogen maser clocks as well.

- "The supply of the first Galileo services has not and will not be affected by the malfunctioning of the atomic clocks or by other corrective measures," Caudet said, and that the malfunctions have not affected service performance.

• June 22, 2017: Europe’s Galileo navigation constellation will gain an additional eight satellites, bringing it to completion, thanks to a contract signed today at the Paris Air and Space Show. - The contract to build and test another eight Galileo satellites was awarded to a consortium led by prime contractor OHB, with Surrey Satellite Technology Ltd overseeing their navigation platforms. 57)

- This is the third such satellite signing: the first four In Orbit Validation satellites were built by a consortium led by Airbus Defence and Space, while production of the next 22 FOC (Full Operational Capability) satellites was led by OHB.

- These new batch satellites are based on the already qualified design of the previous Galileo FOC satellites, except for changes on the unit level – such as improvements based on lessons learned and reacting to obsolescence of parts.

- ESA’s Director of the Galileo Program and Navigation-related Activities, Paul Verhoef, signed the contract with the CEO of OHB, Marco Fuchs and OHB Navigation Director Wolfgang Paetsch, in the presence of ESA Director General Jan Woerner and the EC’s Deputy Director-General for Internal Market, Industry, Entrepreneurship and SMEs, Pierre Delsaux.

• June 8, 2017: Two further satellites have formally become part of Europe’s Galileo satnav system, broadcasting timing and navigation signals worldwide while also picking up distress calls across the planet. These are the 15th and 16th satellites to join the network, two of the four Galileos that were launched together by Ariane 5 on 17 November, and the first additions to the working constellation since the start of Galileo Initial Services on 15 December. 58)

- The growing number of Galileo users around the world will draw immediate benefit from the enhanced service availability and accuracy brought by these extra satellites.

- The launch into space and the maneuvers to reach their final orbits still left a lot of rigorous testing before the satellites could join the operational constellation.

- Their navigation and search and rescue payloads had to be switched on, checked and the performance of the different Galileo signals assessed methodically in relation to the rest of the worldwide system.

- This lengthy testing saw the satellites being run from the second Galileo Control Center in Oberpfaffenhofen, Germany, while their signals were assessed from ESA’s Redu center in Belgium, with its specialized antennas. The tests measured the accuracy and stability of the satellites’ atomic clocks – essential for the timing precision to within a billionth of a second as the basis of satellite navigation – as well as assessing the quality of the navigation signals.

- Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time. — Making the tests even more complicated, the satellites were visible for only three to nine hours a day from each site.

- The satellites are now broadcasting working navigation signals and are ready to relay any Cospas–Sarsat distress calls to regional emergency services.

- Now that these two satellites are part of the constellation, the remaining pair from the Ariane 5 launch is similarly being checked to prepare them for service.

• June 02, 2017: Europe’s Galileo satellite navigation system has undergone its first performance report since it started work at the end of last year – passing with flying colors. The European GNSS Agency, GSA, through its GNSS Service Centre, has published the first of its regular quarterly performance reports on Galileo. This ‘European GNSS (Galileo) Initial Services Open Service’ report, now available online, covers the first three months of 2017, and documents the good performance of Galileo Initial Services to date. 59)

- The report shows the 11 satellites then operating in the Galileo constellation were able to provide healthy signals 97.33% of the time on a per satellite basis, with a ranging accuracy better than 1.07 m and disseminating global UTC time within its signal to within 30 billionths of a second on a 95 percentile monthly basis.

Satellite Code


CCSDS ID [hex]

Orbital Slot

























































Table 3: Galileo reported constellation information

- “Galileo Initial Services were declared by the European Commission on 15 December 2016,” comments Joerg Hahn of ESA’s Galileo System Office. “It was thanks to the tremendous effort of ESA’s Galileo team working closely together with colleagues from the Commission and GSA that this milestone could be achieved: the key pillars for reaching are the currently deployed Galileo satellites in combination with the global Galileo ground segment infrastructure, defined and implemented by the ESA team with their respective industry partners.”

- The Initial Service performance levels (Figure 39) achieved by the system are monitored using two complementary monitoring platforms: the Time and Geodetic Validation Facility, an independent precision time-measuring system accurate to a billionth of a second – using an ensemble of atomic clocks located at ESA/ESTEC in Noordwijk, the Netherlands – and the GALSEE (Galileo System Evaluation Equipment), based in Rome, Italy.


Figure 39: SISE constellation 95%, March 2015-April 2017 (image credit: EC, ESA)

- In the future, the independent monitoring of the services will be carried out by GSA’s Galileo Reference Centre, currently taking shape beside ESTEC in Noordwijk. The results for the first quarter of 2017 show the measured performances are generally far better than the minimum performance levels identified in the Service Definition Documents.

- “Looking back over the ranging accuracy of the Galileo constellation from the time of the very first positioning fix in 2014 to the present, the overall performance trend for the Open Service is very positive,” adds Joerg Hahn. ”It has reached values of less than 1 m in recent months, being already competitive with other satellite navigation systems. The high-quality ranging service enables user level positioning with a typical accuracy of around 3 m on the ground and 5 m in altitude during periods when four satellites are visible. With the limited infrastructure so far deployed, current horizontal position fixes can be achieved during more than 80% of the time with accuracies better than 10 m. This user level performance is expected to improve with the launch of more satellites making the provided Galileo services more accurate, more available and more robust for end users.”

• March 28, 2017: Eutelsat and GSA (GNSS Agency) Europe signed an 18-year contract covering the preparation and service provision phases for the EGNOS (European Geostationary Navigation Overlay Service) GEO-3 payload that will be hosted on the Eutelsat 5 West B satellite that is due for launch late in 2018. The new payload marks a replenishment of current EGNOS capacity and is scheduled to start service in 2019 for 15 years. 60)

- EGNOS V3, the second generation of the EGNOS System, will implement a second protected frequency (L5) to offer to the dual frequency safety of life users a more robust and accurate vertical guidance service (increased robustness with respect to the ionosphere), according to the ESA’s EGNOS V3 Phases C/D - Summary Statement of Work. Version 3 of EGNOS will add a second frequency (L5) and a second GNSS constellation (Galileo) to the GPS L1 corrections currently being provided by EGNOS.

- With the deployment of Galileo and the introduction of new capabilities in GPS, EGNOS V3 will offer improved SoL (Safety of Life) services to the civil aviation community as well as potential new applications for maritime or land users, thus showcasing the system’s increased potential to become a leading edge GNSS system in the future.

- EGNOS operational messages are currently broadcast via navigation payloads on-board two GEO satellites, including an Inmarsat-3F2 satellite that is fast approaching end-of-life. The GEO-3 services will replenish the EGNOS SBAS payloads, guaranteeing EGNOS SIS availability and supporting the transition to the dual-frequency multi-constellation-capable EGNOS V3.

• February 28, 2017: Vidal Ashkenazi, a leading authority and advocate of Europe’s Galileo satellite navigation system has been named as an Officer of the Order of the British Empire by Her Majesty Queen Elizabeth II for services to science. 61) 62)

- Vidal Ashkenazi is an expert in geodesy, the science of Earth measurement, as well as satellite navigation, with a 33 year academic career at the University of Nottingham in the UK.

- As the founding Director of the Institute of Engineering Surveying and Space Geodesy, Prof. Ashkenazi has supervised about 50 PhD students, most of whom occupy senior positions in industry and academia worldwide. In 1998 he left the University to found Nottingham Scientific Ltd, a company that specializes in Global Navigation Satellite System critical applications, involving safety, security and national policy.

- In 1976 he was invited by the US National Academy of Science to come to the US National Geodetic Survey to help develop a standardized coordinate system for mapping and satellite navigation. He contributed to the development of a standard geodetic coordinate system for satellites, known as WGS84 (World Geodetic System 1984), today in common global use.

- In the late 1990s this led to the resurveying of all the major airports around the world to the WGS84 standard. At the request of Eurocontrol, he was directly involved in carrying out this task across the UK and in continental Europe.

- Prof. Ashkenazi also played an important role as Galileo began to take shape, for example by leading the group of academic experts in the European Commission’s GNSS-2 Forum in 1998, gathering together all the major European experts in the field. His direct advocacy proved influential, when in 2003 he addressed the European Parliament’s Industry, External Trade, Research and Energy Committee on why Europe needed its own satellite navigation system.

- Drawing on his transatlantic contacts, he was invited to the US Department of Commerce to address a senior US government and industrial audience on Galileo. He did this by giving a presentation entitled “Galileo: Friend or Foe?” promoting an approach of partnership rather than competition between GPS and Galileo that has indeed come to pass.

- In 2005, the then Director of Navigation at ESA invited Prof. Ashkenazi and his company to make the first study on Galileo evolution, known today as the post-2020 Galileo Second Generation.