A review of cooperative and uncooperative spacecraft pose determination techniques for close-proximity operations

The capability of an active spacecraft to accurately estimate its pose with respect to a target orbiting in close-proximity is required by activities like formation flying, on-orbit servicing, active debris removal, and space exploration. According to the specific mission scenario, pose determination involves theoretical and technological challenges related to the search for the most suitable algorithmic solution and sensor architecture. Electro-optical sensors represent the best technological option being compatible with mass and power limitations of micro and small satellites, and their measurements can be processed to estimate all the pose parameters. The degree of complexity of pose determination largely varies depending on the nature of the targets, which may be cooperative or uncooperative (known or unknown) space objects. In this respect, while cooperative pose determination has been successfully demonstrated in orbit, the uncooperative case is still under study. Since the demand for applications for which pose determination capabilities are mandatory is significantly increasing, a literature review of techniques and algorithms developed for cooperative and uncooperative pose determination by processing data from electro-optical sensors is herein presented. Specifically, their main advantages and drawbacks in terms of accuracy, computational complexity, and sensitivity to variability of pose and target geometry are highlighted.