European Data Relay Satellite System (EDRS)

ARTES 7 EDRS is dedicated to the development and implementation of the European Data Relay System (EDRS).

Data relay satellites are placed in geostationary orbit to relay information to and from non-geostationary satellites, spacecraft, other vehicles and fixed Earth stations that otherwise are not able to permanently transmit/receive data.

EDRS is an independent European satellite system that reduces time delays in the transmission of large quantities of data. It contributes to a telecom network that is fast, reliable and seamless, thereby enhancing Europe's self-reliance. The EDRS makes on-demand data available at the right place at the right time.

WHY

Despite recent advances in telecommunication capabilities, there are still a number of limitations that delay the delivery of time-critical data to users. With the implementation of the joint ESA/European Commission Copernicus programme, it is estimated that European space telecommunication infrastructure will need to transmit 6 terabytes of data every day from space to ground.

Our present telecom infrastructure is now charged with delivering these large data quantities without significant delays, when conventional means of communication may not be sufficient to satisfy the quality of service required by users of Earth observation data. In addition, Europe currently relies on the availability of non-European ground station antennas to receive data from Earth observation satellites. This poses a potential threat to the strategic independence of Europe, as these crucial space assets may effectively not be under European control. EDRS offers a solution to these issues.

EDRS PROVIDES:

• Real time access to Earth observation data
• High data rates
• Encrypted data downlink
• Fast forward commanding capability

THERE ARE A NUMBER OF KEY SERVICES THAT BENEFIT FROM THIS SYSTEM'S INFRASTRUCTURE:

• Earth observation applications in support of a multitude of time-critical services, e.g. monitoring of land-surface motion risks, forest fires, floods and sea ice zones
• Government and security services that need images from key European space systems such as Copernicus.
• Rescue teams that need Earth observation data within disaster-struck areas
• Security forces that transmit data to Earth observation satellites, aircraft and unmanned aerial observation vehicles, to reconfigure such systems in real time
• Relief forces operating in remote areas that require telecommunication support 

EDRS Copernicus Sentinel services (click to enlarge)

WHO

In order to achieve a cost efficient EDRS programme and minimise ESA investment and operation costs, EDRS is being implemented as a Public Private Partnership (PPP) through ESA’s ARTES programme.

Airbus Defense and Space (formerly Astrium) (D)  is serving as prime contractor. It won a competitive tender issued in 2010 and will carry the overall responsibility for the implementation of the space segment (including launch) as well as the ground segment. 

Airbus has commited to operating the EDRS for 15 years and provide services to ESA, in particular for the Copernicus programme. Sentinel-1A (launched in April 2014) and Sentintel-2A will be two key Copernicus users.

WHAT

EDRS consists of two geostationary nodes and an extensive network of European ground and control centres that together ensure Europe receives uninterrupted coverage from satellites orbiting around the globe.

THE EDRS SPACE SEGMENT

The first EDRS payload, EDRS-A, comprising an optical inter-satellite link and a Ka-band inter-satellite link is hosted on satellite operated by Eutelsat (FR) known as EUTELSAT 9B EAST. Launched in 2016. Its orbital position will be 9 degrees East.

The second EDRS payload, EDRS-C, also consisting of an optical inter-satellite link, is hosted on a platform developed on the basis of the SmallGEO, which began as a public private partnership (PPP) scheme between OHB (DE) and ESA as part of the ARTES programme. EDRS-C has been successfully launched on the 6 August 2019. The EDRS-C mission also carries a commercial payload, Hylas-3, developed by UK-based Avanti Communications. Through this arrangement, the cost of satellite resources and the launch are shared. This contributes to the funding of the EDRS programme while providing access to space at a lower cost for the hosted payload.

Avanti and ESA previously worked together to launch the Hylas-1 satellite in 2010. Hylas-3 includes a steerable multibeam antenna to provide communications for institutional and commercial Avanti customers independent of EDRS.

Once fixed in geostationary orbit, the two satellites serve as a data relay backbone. The inter-satellite communication terminals (optical and Ka-band inter-satellite links) will offer speeds of up to 1.8Gbit/s (optical) and up to 300Mbits/s (Ka-band), while the Ka-band feeder link will offer speeds of up to 300Mbits/ to the ground. The data will be received either at dedicated EDRS ground stations or potentially at future user ground stations which would provide direct access to the data. The EDRS ground stations are all be based in Europe.

The most innovative part of the inter-satellite service is the laser communication terminal. It has been developed by TESAT Spacecom GmbH (D) under contract by the German Aerospace Center (D). The new terminal has been validated in orbit on-board the German Terrasar-X satellite and on-board the US NFIRE satellite.

The first optical inter-satellite link between these two satellites was tested in 2008 and resulted in a 5.6 Gbit/s data rate transmission for distances of up to 5,000km. The newer second-generation terminal can transmit distances up to 45,000 km at a data rate of 1.8 GBit/s.

Both optical and Ka-band inter-satellite services are transparent to the data routed via the system. No data will be stored on-board; however encryption services are available on request by the user.

THE EDRS GROUND SEGMENT

Offering data relay services on a commercial basis is complex and requires a substantial investment in ground services.

The EDRS Mission Operation Center is located in Ottobrunn (D) with Redu (B) serving as a backup.

The planning details may vary from user to user, but basically service requests contain information on the orbital position of the communicating satellite, the planned duration of the link, and the handling of the data on-ground.

Such information, together with the planning constraints of the EDRS system and the user satellite are defining the overall service schedule.

Based on the information described above, the mission operations centre tasks the corresponding ground segment elements – either the one related to EDRS-A or the one related to EDRS-C.

Due to the high data rate requirement for the download of 1.8 Gbit/s, the Ka-band frequency used for the feeder link and required reliability of EDRS (99.6 % uptime), the system is equipped with a data consolidation network.

In addition to the EDRS data receiving stations, users may choose to receive the data at their own ground stations in order to have direct access to it. 

WHERE

EDRS-A geostationary orbital position will be 9 degrees East.

EDRS-C geostationary orbital position is be 31 degrees East.