Sentinel-1C&D System

This paper explains the design changes between the Sentinel-1A and Sentinel-1B satellites (S1 A&B) and the new, Sentinel-1C and Sentinel-1D satellites (S1 C&D). S1 C&D will replace the, currently in-orbit, and fully operational S1 A&B, when the end of life of each satellite is reached. S1 C&D will each embark a Satellite Automatic Identification System (AIS) and implement design modifications to improve system performance and robustness taking into account lessons learned from the S1 A&B programmes. In particular, the paper discusses the main characteristics of the Automatic Identification System (AIS) instrument to augment the SAR payload data for maritime ship traffic applications, the avionics system for improved attitude knowledge and SAR antenna pointing, and the propulsion system for fast orbit acquisition. Finally, the design of Sentinel-1C and Sentinel-1D incorporates novel solutions that will make both satellites fully compliant with the latest Space Debris code-of-conduct and the required casualty risks at re-entry.