Accuracy of satellite orbit prediction and optical design of optical ground station beacons for satellite-to-ground optical communication

In recent years, spatial optical communication has been attracting attention as a large-capacity communication method that connects satellites and the ground. Radiofrequency communications are used as a method for transmitting data acquired by satellites to the ground. However, the radio frequencies used make it difficult to improve the communication speed, owing to interference problems and the carrier frequency. Space optical communication is expected to be a solution to this issue. A beacon method is often used to emit light from an optical ground station toward a satellite for initial acquisition. It is desirable that the divergence angle of the irradiating beacon covers the range of satellite orbit prediction. Therefore, it is important to know the orbit prediction accuracy of a satellite. In the experiment, satellite flare was observed from a ground station and verified by comparing the telescope tracking data with the GPS data and NORAD-TLE information mounted on the satellite.