The TOWS study aims at making practical the use of Optical Wireless Communications (OWC, aka Li-Fi) in telecommunication spacecrafts, analysing the potential applications, selecting the most practical ones, developing the corresponding OWC systems and including them into TRL5 demonstrators. To reach these goals, TOWS effectively combines the expertise of design and realization of Li-Fi systems, demonstrated by the Prime in several prototype realizations for terrestrial applications, with the deep knowledge of the space industry needs and best practice, which is provided the Subcontractor. The finalized Li-Fi systems will be therefore optimized with particular focus on the most recent system and components solutions for Li-Fi, as well as the today’s scenario of telecom satellites. In all realizations, the key objective will be to use COTS and realize transparent connections, which do not ask for relevant modifications of existing network and protocol features.