Analysis and design of close operations at Phobos

This Thesis presents the analysis of a descent maneuver to the Martian moon Phobos, treated mathematically as a Low-Thrust Optimal Control Problem. In order to increase the accuracy of the problem, the gravity acceleration at each of the trajectory nodes is obtained by applying the Polyhedron method, discussed in Chapter 2. The following document is structured by discussing rst the general aspects of the problem analyzed, focusing then completely on the Optimal Control Problem solved. Firstly, the scienti c aims that a mission to Phobos presents are discussed, together with the uncertainties that are still present when studying a mission to this Martian moon. Then, a theoretical approach to the Polyhedron method is discussed, as well as the reasons by which this method is chosen ahead of others. From that point on, a closer approach to the problem is made; rst, by making a general theoretical discussion about the numerical methods present in the GPOPS program that could be used to solve the problem stated, reasoning then the election made and the aspects that have prevailed for this decision to be taken. Subsequently, a detailed characterization of both the dynamical and path constraints implemented is made, as well as a brief description of the propulsive parameters chosen and the reference frame selected, in the same fashion as other articles [1] that treat a descent maneuver too. Finally, the analysis is centered exclusively on the solving process followed. The computational work carried out is explained rst, detailing the modi cations made in order to overcome the computational resources' problem that arose. The results for the optimization are then presented, making a thorough description of the physical phenomena occurring in the spacecraft dynamics. As concluding remarks, a summary of the results obtained is made, together with their limitations; a roadmap for future work is added too, setting the steps that should be taken in the future for making an even more realistic study, which could be used as a rst pragmatic approach to propose a real mission to Phobos.Ingeniería Aeroespacia