The European Data Relay System, high speed laser based data links

The European Data Relay System (EDRS) is currently implemented as the first operational laser based data relay service, creating a virtual ground station for low earth orbit earth observation missions. It is based on the Tesat Laser Communication Terminal (LCT), which was developed under contract from DLR for continuous communication service in LEO and GEO orbits. The paper details the structure, development and verification of the LCT, and describe the developments at Tesat for single photon heterodyne detection, that can be used as receiver for deep space communication links to enable communications even under severe background noise levels like near to sun communication links.