This Horizon Europe grant is to be understood within a wider context on EUSST, where other grants are being executed simultaneously with the common objective of improving the EU autonomy on Space Surveillance and Tracking. In particular, this TOP focuses on: - Study and assess several technical solutions for the development of a future European capability of SBSS. - Explore the use of small satellite solutions to reduce CAPEX and OPEX - To develop in the mid-term the European capacity to operate independently SBSS. - To reduce the dependence on critical SBSS technologies and capabilities from outside Europe, The is the first activity related to SBSS within EUSST.