This thesis is the result of a collaboration between Politecnico di Torino and the Royal Melbourne Institute of Technology. This work aims to develop an automated algorithm to reorient small satellites and change their orbit to avoid debris collisions. In a context where it is essential to reduce costs this concept of a space telescope is presented. This thesis outlines an optimal strategy for trajectory and attitude reorientation for autonomous SmartSats. On-board autonomy allows to reduce the workload on ground-stations and will be mandatory in the next future where satellites will need to accomplish their mission autonomously. This satellite shall be able to optimise its attitude and its trajectory on-board and in real-time.