The European Union Agency for the Space Programme (EUSPA) and Naviair — a company that specializes in air navigation and related infrastructure services and is owned by the Danish state and represented by the Ministry of Transport — have partnered to strengthen the monitoring capabilities of the Galileo search and rescue (SAR) service by adding a new site in Greenland.
The partnership between EUSPA and Naviair will expand the ground segment and current SAR capabilities. As part of the agreement, Naviair will contribute to the Galileo Programme objectives by procuring, deploying, hosting, and operating a reference beacon (REFBE) near the Kangerlussuaq Airport in Greenland.
The new SAR/Galileo site and REFBE will be located around the margins of the declared service coverage area and will be fully integrated into the SAR ground segment, bringing the number of REFBEs to eight. The REFBEs provide data for service performance monitoring.
There are currently five REFBEs in the European coverage area and two in the Indian Ocean coverage area.
The REFBEs are fitted with vertical linear polarized antennas that transmit timely, synchronized signals equivalent to a standard 406 MHz Cospas-Sarsat beacon. This, combined with their well-known position, enables specific SAR/Galileo Service performance indicators to be derived.
The new site will be ready by the fourth quarter of 2023.
The SAR/Galileo component of the EU Space Programme plays a crucial role in the detection of emergency signals transmitted by distress beacons in support of the internationally recognized SAR Cospas-Sarsat program. As part of this program, the Galileo SAR Service utilizes SAR instruments onboard Galileo satellites, medium-Earth orbit local user terminals, and a network of SAR REFBEs located across Europe.
As well as providing global navigation services, Europe’s Galileo satellite constellation is contributing to saving more than 2,000 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.
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.
Cospas-Sarsat rescue beacon activated. Its signals are picked up by satellites in orbit, including Galileo. (Photo: GSA)
“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 percent of onboard power, with their receive-transmit repeater housed next to the main navigation antenna.
Image: ESA
Founded by Canada, France, Russia and the US in 1979, Cospas-Sarsat began with payloads on low-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.
Geostationary 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.
Medium-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 localise SOS signals. This improves the maximum signal detection time from four hours to less than five minutes, down to one or two kilometres (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 Global Navigation Satellite System Agency, GSA, 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 centre 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.
A public demonstration of Galileo’s return link service was performed at the Cospas-Sarsat Joint Committee Meeting in Doha in Qatar in summer 2019. ()Photo: ESA)
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.”
By Javier Benedicto
Head, Galileo Programme department,
European Space Agency
Javier Benedicto, left, accept the 2018 GPS World Satellites Leadership Award on behalf of Giuliano Gatti of the European Space Agency, from Phil Froom of Rockwell Collins. (Photo: Melanie Beus)
Since the Galileo initial services declaration in December 2016, the Galileo Program has been providing global PNT and search-and-rescue services for users worldwide. The European GNSS Agency (GSA) just issued its GNSS 2019 Market Report in October, providing a complete overview of the current status and trends of the GNSS worldwide market with focus on European GNSS (Galileo and EGNOS) applications and services.
In parallel with service provision, the Galileo Program is undertaking extensive infrastructure development and deployment activities to reach Full Operational Capability (FOC), incorporating new service capabilities, but above all aiming at increasing the robustness and resilience of the system infrastructure, operations and service provision.
Galileo’s signal-in-space quality has steadily improved over the past few years, reaching in 2019 a best signal-in-space error (SISE) of about 0.25 meters (95%, global average; Figure 1). This has been achieved through a combination of several factors, including the increased number of operational satellites, enhanced versions of the Ground Mission Segment, and higher uplink rate of the navigation message (lower age of data). This performance is well within Galileo’s initial service accuracy commitments, as defined in the public Open Service – Service Definition Document (OS SDD).
Figure 1. Long-term historical SISE plot over a 30-day sliding window, constellation averaged. (Image: ESA)
Figures 2 and 3 (see page 40) show Galileo’s timing performance as broadcast UTC offset and GGTO accuracy. The evaluation was performed with calibrated GPS/Galileo timing receivers operated in UTC(k) laboratory (PTB, INRIM). Again, the initial timing service commitments have been fully met.
Probably the most significant discriminator of Galileo compared to other GNSS is its capability to broadcast multi-frequency (E1, E6, E5) signal components on all operational satellites. The position performance of a dual-frequency user receiver on-ground is shown in Figure 4. This measurement from June 2019 demonstrates a Galileo position accuracy well below 2 m (95%).
Figure 4. Galileo position accuracy performance, dual-frequency, June 2019. (Image: ESA)
With the aim of further improving the Open Service (OS) performance, three newly introduced I/NAV message improvements on Galileo E1-B are under implementation, namely FEC2 Reed-Solomon Clock and Ephemeris (CED), Reduced CED, and Secondary Synchronization Pattern (SSP). Galileo Open Service (OS) users will benefit from improved robustness in terms of navigation data retrieval in challenging environments, in addition to facilitating a reduced time to first fix. Those I/NAV improvements on Galileo E1-B are backwards compatible with previously released OS SIS ICDs.
In addition, Galileo infrastructure is currently being upgraded to provide means for OS authentication. The protocol proposed uses the E1B External Data Broadcast Service (EDBS) to provide authentication data to the user. The OS Navigation Message Authentication (NMA) is based on an adaptation of the Timed Efficient Stream Loss-tolerant Authentication (TESLA) protocol.
Beyond the OS, the Galileo system has been designed to allow for the dissemination of value-added data, such as high accuracy and authentication, in the E6B signal component. The component has been designed to broadcast the Galileo High Accuracy Service based on the provision of accurate satellite data (clocks, orbits and biases) and atmospheric data (mainly ionospheric corrections) to enable multi-frequency multi-constellation PPP with correction data transmitted through an open format in the Galileo E6B signal.
The introduction in early 2020 of the automatic acknowledgment of the SAR/Galileo Return Link Message (RLM) as part of the Cospas-Sarsat system will enable space assets to be used for search and rescue — persons in distress will get swift acknowledgement that their alert has been detected and located. The Return Link is the means to interact with a SAR beacon, improving the effectiveness of SAR operations. Extensive testing has demonstrated that the median latency for the reception of a return link message on the ground is 14.2 seconds, while 99% of messages are received within 57 seconds, after the request for the RLM transmission is delivered to Galileo (from Cospas-Sarsat to the RLSP). At the same time, the measured rate of reception was 100%, considering line-of-sight availability, thanks to the very robust Galileo navigation data link. This performance has been demonstrated to be uniform across the globe, as shown in Figure 5.
Figure 5. Beacon activation map and RLM delivery latency through the Galileo system. (Image: ESA)
Following the re-profiling of the Galileo Safety-of-Life (SoL) service, Galileo is meant to be exploited through dual-frequency multi-constellation (DFMC) SBAS and will support the provision of integrity through the concept of Horizontal Advanced Receiver Autonomous Integrity Monitoring (H-ARAIM). To allow the exploitation of Galileo for these SoL applications, a thorough analysis of the actual signal-in-space (SiS) performance and of potential feared events critical for SoL users is key. In this context, the Galileo Integrity Failure Mode and Effect Analysis (IFMEA) process is implemented through measurements and review of the system design, including feared-events characterization.
Ground Segment Brings Robustness
Galileo telemetry and telecommand ground station. (Photo: ESA)
Galileo’s Ground Segment is being upgraded to fully redundant control centers. These include processing and storage, monitoring and control facilities, and security monitoring centers. A worldwide network of Galileo Sensor Stations (GSS) allows monitoring and measuring of satellite signals; uplink stations allow dissemination of the navigation message to users through Galileo satellites; and telemetry, tracking and control (TTC) stations allow monitoring and control of the satellites.
Ground segment upgrades under production by Thales Alenia Space France (in charge of the ground mission segment and security monitoring) and GMV Spain (in charge of the ground control segment) are addressing increased service robustness, through the introduction of a more flexible infrastructure with a significant technology refresh, improved security, service continuity, enhanced service performances, and enhanced operability features.
One important objective of the ongoing upgrades is to implement a modern infrastructure, based on leading virtualization technologies. This modernized infrastructure will make it possible to easily accommodate hardware and software changes without requiring significant redesign or requalification, and will minimize the impact to Galileo service operations — under responsibility of Spaceopal GmbH — during future deployment activities.
Batch 3, Ariane 6 Under Production
Ariane 6 on the launchpad. (Artist’s concept: ESA)
The production of Batch 3 of 12 additional Galileo FOC satellites is proceeding, aiming at readiness for launch by the end of 2020 onward. The satellite design includes a selected number of improvements compared to the 22 FOC satellites launched previously and built by the same satellite manufacturer OHB Systems.
The different stages of assembly, integration and initial test phase in the OHB production plant in Bremen have already started, before shipment to ESA-ESTEC in the Netherlands for the environmental test campaign consisting of thermal vacuum, mechanical tests, interface verification with the launcher and system end-to-end performance tests with the elements of the Galileo ground segment.
Following the phasing out of the Ariane 5 SE launcher, the third batch of Galileo satellites will be progressively launched with the new Ariane 62 launcher vehicle, the two solid-booster variant of Ariane 6 now in the final stages of development.
Evolution to Meet User Needs
The Galileo Second Generation roadmap has achieved maturity in 2019 and is now entering the preliminary design and implementation phase. Based on the EU’s H2020 Galileo Second Generation activities managed by ESA, and the GSA prospective market analysis, the European Commission, in close consultation with EU member states, has agreed on an ambitious set of long-term PNT goals for the future European GNSS infrastructures.
Technology pre-developments, critical engineering activities and synergic design activities between space and ground infrastructure are being conducted. This will translate into the progressive deployment of a complete set of space/ground infrastructure that is tailored to satisfy the diversified user needs in four main dimensions:
Satellite and ground segment infrastructure with capabilities that can dynamically adapt to current and future user needs. Key drivers are flexibility and robustness, ensuring fast time to market to meet user needs.
Full synergy between GNSS and SBAS systems infrastructure, to complement and enhance the service portfolio. This will allow segmentation and complementarity of safety-critical services and extension to all new PNT services available today, including high-accuracy positioning integrity.
Enhanced integration with terrestrial systems — 5G/6G, signals of opportunity (SOOP), terrestrial beacon systems (TBS). ESA and GSA have been actively leading the 5G positioning standardization worldwide in collaboration with public and private institutions inside 3GPP and will soon move toward the start of standardization of 6G terrestrial positioning and GNSS interconnection technologies.
Full complementarity with external sensors (such as INS, barometer and lidar) and application environments (low-power devices and internet of things) so that the Galileo Second Generation Infrastructure enhances and complements the capabilities provided by these external means.
A key pillar for this long-term strategy is the Galileo transition satellites. The competitive procurement procedure for the first batch of transition satellites is coming in 2020. The flexibility and robustness of these satellites will allow the European PNT infrastructure to satisfy all the different user needs in the next decade. This procurement — together with others at system, ground segment and technology level — will enable the start of the in-orbit validation of second-generation capabilities from 2025 onward.
Additional ground and test infrastructure are in early engineering analysis, design and technology development, in order to proceed with additional procurements for experimental and operational usage, starting early in the 2020s.
Operation Shark Bait showed how this vital service can quickly trigger a rescue operation and save lives at sea. Despite a grey day and choppy sea conditions, an emergency rescue was initiated in just over three and a half minutes after intrepid “volunteer victim,” Australian broadcaster and explorer Tara Foster, operated her Galileo-enabled SAR beacon from a small life raft buffeted by the waves just offshore from the port of Ostend.
Operation Shark Bait was a specially designed demonstration of the capabilities of the Galileo SAR service that took place around the new state-of-the-art Belgian Maritime Rescue and Coordination Centre (MRCC) in Ostend with an invited audience of VIPs and media. The whole operation was streamed live over YouTube and the Europe By Satellite (EBS) TV service.
The Shark Bait test took just over three and a half minutes to locate the PLB developed under a GSA Horizon 2020 project. (Photo: GSA)
The scenario was simple. Tara was left alone at sea in a small life raft, but with a 406-MHz Cospas-Sarsat personal locator beacon (PLB). On activating the beacon, the stopwatch started. The time to receive the distress signal, compute her position and alert the relevant rescue authorities was recorded. The Belgian fast rescue boat ORKA R6 then dashed out to sea to pick her up.
Subsequently, a NH90 Cayman SAR helicopter from the Belgian 40th squadron was also scrambled to help transfer “injured” Tara to hospital.
Shark Bait was a great success with just 3 minutes 32 seconds elapsing from Tara activating her Galileo-enabled personal locator beacon (PLB) to the moment commanders at MRCC could dispatch the ORKA to her location.
The location, with an initial accuracy of 100 metres, is provided by the Galileo receiver inside the PLB to the Galileo satellites in view. The Galileo satellites then forward this information to the Cospas-Sarsat infrastructure, where the position is validated.
“The PLB used was developed under one of our Horizon 2020 projects and is the first Galileo-enabled beacon on the market,” said Fiammetta Diani, head of market development at the GSA.
Time saver, life saver
The day started at the MRCC in Ostend with a visit to the operations centre, an inspection of the ORKA Fast Rescue Boat and a chance to talk to Tara Foster before she was “castaway” on the waves.
Dries Boodts, deputy nautical director at MRCC, described the role of the center, which has a single focus on safety at sea. “The globe is divided into Search and Rescue Regions (SRRs),” Boodts said. “The MRCC oversees the Belgian maritime region that extends up to 47 miles off the Belgian coast.”
The region includes major shipping lanes and two large offshore wind energy parks. The MRCC deals with around 450 incidents each year involving a range of craft and issues from collisions at sea to war munitions recovery. It can call on an assortment of assets including its own rescue craft, police and navy vessels and the Belgian air force and the MRCC collaborates extensively with authorities in neighbouring countries.
Galileo is Europe’s contribution to upgrading Cospas-Sarsat, the global satellite-based search-and-rescue system. Since its introduction in 1981, Cospas-Sarsat is estimated to have saved 45,000 lives.
The current MEOSAR (Mid-Earth Orbit Search and Rescue) upgrade is based on the EU’s Galileo satellite constellation that carries a dedicated Cospas-Sarsat payload for the 406-MHz distress beacons that give users free access to global system.
The addition of Galileo (and other GNSS satellites) to the system has already enabled a dramatic increase in performance in terms of better accuracy to locate activated distress beacons and vastly improved global coverage.
“With the Galileo system, all parts of the world will be covered at least every 10 minutes — previously this was up to four hours — and guaranteed location accuracy is reduced from 10 to 2 kilometers,” explained Jolanda van Eijndthoven from the European Commission.
As well as the 23 SAR payloads currently provided by Galileo, with more to come, the EU also provides ground infrastructure including MEO Local User Terminals (LUTs) to pick up the signals relayed from the satellites. These LUTs are not just in Europe, and a fourth facility is o be opened soon on La Reunion island to improve coverage across the Indian Ocean.
Return link reassurance
From the end of the year the Galileo system will also provide a Return Link Service (RLS) that will be able to send an acknowledgement to the victim that their distress signal has been received and help is on its way. This new ability to provide reassurance should deliver a valuable psychological lift to victims and further boost survival rates.
“The PLBs developed under our Horizon 2020 projects will be the first ones on the market to have the RLS capability,” said Fiammetta Diani.
Back on dry land, Tara confessed that the simulation had felt very real to her. “The scariest part was the transfer to the helicopter from the rescue boat,” she said. “The winch was like a lift without a floor and very fast! Stepping from the flimsy life raft to the ORKA was also not easy – those waves were high!”
“The operation went just like clockwork,” concluded Paul Flament Head of the Galileo and EGNOS unit at the European Commission’s DG GROW.
