On the determination of preliminary orbits and detection of possible conjunctions for space debris

Since the last decades, solutions devoted to space debris issues have been investigated. Indeed, several investigations came up with the same conclusion done by the 'Kessler syndrome': the increase of this population could lead to an unstoppable cascade effect of collisions of objets in the near-Earth environment. The research in this thesis focuses on the orbit determination problem and the identification of conjunctions of these objects. A new algorithm is introduced and consists in determining preliminary orbits for objects in Low Earth Orbit based on correlation of radar observations. Using the evolution of the trajectories, a procedure is developed to select the pairs that have potential close encounters.