The communication experiment result of Small Optical Link for ISS (SOLISS) to the first commercial optical ground station in Greece

Free-space optical communication (FSOC) in low-Earth orbit (LEO) is one of the most active areas of research and development in space communication technology. Since LEO has narrower coverage than higher orbits, optical communication terminals need to support multiple optical ground stations (OGSs) for sufficient link opportunities. In addition, considering that optical lasers are more susceptible to bad weather than radio waves, supporting multiple stations is also effective in terms of site diversity. Recently, Sony Computer Science Laboratories (Sony CSL) and Kongsberg Satellite Services (KSAT) conducted a successful experiment to downlink data from an optical communication terminal attached to the International Space Station (ISS) to an OGS in Nemea, Greece. In this paper, we report the results of the demonstration. The space terminal used in the experiment is the same individual used in a previous demonstration of Sony CSL that achieved optical communication with an OGS in Japan, indicating that our space terminal is compatible with independently designed multiple OGSs. More to the point, KSAT designed their OGS for commercial use, with low complexity and cost-competitive to radio ground stations. Our terminal is compatible not only with OGSs established for specific missions but also with such small and generic commercial OGSs, which could contribute to the widespread use of our optical communication terminals in orbit. In the future, the OGS used in this study will be connected to the Optical Nucleus Network, which is a network of OGSs. Since it is significant to be able to utilize such terrestrial resources, we plan to continue our development while maintaining compatibility with various OGSs.