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Sentinel-1 C/D: modifications and enhancements

This manuscript presents the improvements implemented on the future Sentinel-1C/D spacecraft, which will eventually replace the current in-orbit Sentinel-1A/B satellites. Changes are based on the Sentinel-1A/B lessons learnt and on the addition of new functionalities to improve the system performance. More specifically, the modifications that will be covered in this paper are those that will enhance the performance of the mission. The addition of an Automatic Identification System (AIS) will provide ship position and identification while operating the SAR instrument. The Attitude and Orbit Control System (AOCS) will be upgraded to improve the pointing stability and to be compatible with the new Galileo signals. A novel mechanical bracket interfacing the SAR central panel and the platform has been designed to facilitate the disintegration during the re-entry. The propulsion system has also been modified to allow a faster orbit acquisition. The upgrades done on the SAR instrument to improve the radiometric stability will be also detailed.