Operational Results of JAXA’s Optical Data Relay System LUCAS as of Oct. 2025

Japan Aerospace Exploration Agency (JAXA) has developed the Laser Utilizing Communication System (LUCAS) onboard the optical data relay satellite that was launched in November 2020. In September 2024, JAXA successfully conducted an in-orbit technology demonstration between LUCAS and the first user satellite ALOS-4, launched in July 2024. The user data rate of 1.8Gbps is the largest demonstrated for LEO-GEO link at 1.5um as of Oct. 2025. This manuscript provides the evaluation results of the acquisition and tracking sequence, directional stability, and communication quality during the demonstration, confirming the practical implementation of the LEO-GEO scenario with real-time laser communication.