Within the scope of the FALCON project Mynaric Lasercom GmbH, in collaboration with Facebook Inc., has built two laser terminals for optical communications: One airborne terminal MLT-70-ATG and one optical ground station GS-200. Both terminals are designed to establish communications between the stratosphere and ground. The athermalized design of the MLT-70-ATG, its efficient temperature management system and an optimized dynamic behavior for high-altitude platforms qualify Mynaric’s system to be easily integrated into carriers that fly up to tens of kilometers. The GS-200 achieves and sustains fast and reliable free-space data transfer links between the airborne segment and ground. It is designed for outdoor operations and is mounted on a stationary stable platform. A flight campaign executed by both companies has demonstrated a 10 Gbps bidirectional error-free link between the airborne laser communication terminal and the optical ground station in a representative scenario. The optical link was acquired successfully in a few seconds and both terminals maintained a steady link. Limitations in the line of sight between the communication partners, due to the flight patterns followed by the aircraft, triggered reacquisitions that were handled by the terminals autonomously. Bidirectional data transmission with maximum data throughput has been achieved. Even for strong fluctuation conditions, which were experienced during ground-to-ground tests, the link was error-free thanks to the coding in the Laser Ethernet Transceiver (LET). The LET converts the user data to a proprietary format. The systems could recover successfully outages up to 10 milliseconds. The coding and synchronization schemes have been optimized for overcoming the inherent spurious effects of the free-space optical communication channel.
Robotic operations in space with telepresence systems require high data rates for sensor and video feedback in combination with very low delays for precise and transparent control. The ESA funded project HiCLASS-ROS (Highly Compact Laser Communication Systems for Robotic Operations Support) demonstrated the use of optical communication links for symmetrical and bi-directional high data rate links in combination with lowlatency channel coding for very low round trip times comparable to a LEO scenario.