Since 2016, the European Data Relay System (EDRS) – also known as SpaceDataHighway – is serving as a geostationary (GEO) relay system offering unique laser communication services for satellites of the low earth orbit (LEO). As the satellite market evolves, today´s LEO satellites produce more accurate, more precise, and more detailed data, and thus struggle with the task of bringing huge amounts of data to ground. EDRS offers a convenient solution to that challenge by its data transfer service via its GEO nodes to ground. In addition to this basic concept, the EDRS mission also involves the technology of optical communication: the space-to-space link is performed in optical frequencies by the means of so-called Laser Communication Terminals (LCTs), offering a secure and high-speed data transfer.
Currently, EDRS consists of two nodes: EDRS-A is a hosted payload on the Eutelsat-9B satellite which was launched in January 2016. It was complemented by the satellite EDRS-C, launched in August 2019, dedicated for the EDRS mission. Both payloads, as well as the EDRS-C satellite platform, are operated by the German Space Operations Center (GSOC), which is part of the German Aerospace Center (DLR). The EDRS program itself is a public-private partnership between ESA and Airbus Defence and Space as the industrial prime contractor. The LCTs are manufactured by TESAT Spacecom, while the 3-ton-class SmallGEO platform built by OHB is the satellite bus for EDRS-C. In addition to the LCTs, which are the prime payloads on both nodes, GSOC also operates a Ka-Band relay antenna as supplementing part of the EDRS mission, a Ka-Band transponder for AVANTI Communications, as well as a radiation monitor of ESA as secondary payloads.
The EDRS system is capable of performing up to 200 communication links with LEO satellites per node and per day. Until mid of 2023, though, the EDRS mission will consist of seven LEO customer satellites, as well as one Ka-band customer antenna (ColKa) on the Columbus module of the International Space Station ISS. All of them are using the EDRS service either via laser communication or the secondary Ka-band antenna. The high numbers of possible links as well as customer satellites pose a challenging task to the control centers at GSOC. For this reason, both LCTs are controlled using an automated operations engine, which is designed to supervise the complete cycle of telecommand uplink and execution as well as reaction monitoring of telemetry, giving GSOC permanent control and awareness. The system has proven to be very robust, is routinely used and led to over 60.000 successful optical links until mid of 2022.
This paper gives an overview over the EDRS mission and shows how GSOC organises and performs EDRS-A and EDRS-C operations. It also describes how both operations evolved during the course of the project, which harmonisations were performed, and gives an outlook on how the future of the program might look from a GSOC perspective
