ESA GNC Conference Papers Repository

The European Data Relay System (EDRS) is a satellite based system placed in geostationary orbit to relay information to/from non-geostationary satellites, spacecraft, other vehicles and fixed Earth stations otherwise not able to permanently be in touch with each other. As part of EDRS, EDRS-C is the first dedicated EDRS satellite of the future constellation. EDRS-C is managed by ESA and Airbus Defense & Space, Germany and OHB System is the prime contractor. The satellite will also host two additional payloads on-board: HYLAS 3, from Avanti Communications, UK and the 'Next Generation Radiation Monitor (NGRM)' developed by RUAG The EDRS-C satellite platform is derived from OHB System's SGEO platform and is modified to meet the EDRS requirements. The operation of the on-board Laser Communication Terminal (enabling the inter-satellite link) imposes pointing and attitude knowledge stability requirements more stringent than on typical GEO satellites. As in SGEO, OHB Sweden is responsible for the AOCS for EDRS-C and as part of this, the development of the AOCS SW which is integrated into the overall EDRS-C OBSW. This paper will first discuss the commonalities and specificities of EDRS-C with respect to the original SGEO platform from an AOCS perspective, explaining how the mission needs have steered the SGEO architecture and design towards the EDRS-C final AOCS SW. In a second part, the article will show how keeping continuity between the projects has been possible thanks to Model-Based Design techniques, and Verification & Validation processes. The paper will also present how some design tools and processes have been further improved in this way.