The paper presents the development of a fully-safe, automatic rendezvous strategy between a passive vehicle and an active one orbiting around the Earth–Moon L2 Lagrangian point. This is one of the critical phases of future missions to permanently return to the Moon, which are of interest to the majority of space organizations. The first step in the study is the derivation of a suitable full 6-DOF relative motion model in the Local Vertical Local Horizontal reference frame, most suitable for the design of the guidance. The main dynamic model is approximated using both the elliptic and circular three-body motion, due to the contribution of Earth and Moon gravity. A rather detailed set of sensors and actuator dynamics was also implemented in order to ensure the reliability of the guidance algorithms. The selection of guidance and control is presented, and evaluated using a sample scenario as described by ESA’s HERACLES program. The safety, in particular the passive safety, concept is introduced and different techniques to guarantee it are discussed that exploit the ideas of stable and unstable manifolds to intrinsically guarantee some properties at each hold-point, in which the rendezvous trajectory is divided. Finally, the rendezvous dynamics are validated using available Ephemeris models in order to verify the validity of the results and their limitations for future more detailed design.
The paper presents a novel application of the State Dependent Riccati Equation (SDRE) guidance approach with state constraints for a chaser spacecraft in the close proximity of a passive target. The dynamics are described by full 6 degree of freedom rigid-body relative motion. The final trajectory is defined by a passively safe approaching cone, which acts as path constraint and follows the attitude motion of target. A Near Rectilinear Halo Orbit in the Earth-Moon system is the selected rendezvous scenario to fully validate the proposed solution, even though the parameters related to the constraints and weighting functions are kept as general as possible, thus applicable to other similar missions.
The paper describes the performance of a guidance law based on the Adjoint and SDRE methods in presence of reality representative models of sensors and actuators during the rendezvous phase of the proposed Heracles mission to the Moon. In recent years, the increased interest in returning to the Moon has motivated the necessity to develop accurate models for the analysis of missions that takes into account realistic system components. The paper reviews the mission's details, the rendezvous/berthing guidance algorithm with third body perturbation, and sensor's and actuators state of the art models. A Montecarlo analysis is used to validate the models in order to satisfy the safety of the trajectory. The results show that the proposed guidance and control are capable of maintaining safe relative motion between the vehicles.
The paper describes the preliminary design of a phasing trajectory in a cislunar environment, where the third body perturbation is considered non-negligible. The working framework is the one proposed by the ESA’s Heracles mission in which a passive target station is in a Near Rectilinear Halo Orbit and an active vehicle must reach that orbit to start a rendezvous procedure. In this scenario the authors examine three different ways to design such phasing maneuver under the circular restricted three-body problem hypotheses: Lambert/differential correction, Hohmann/differential correction and optimization. The three approaches are compared in terms of ΔV consumption, accuracy and time of flight. The selected solution is also validated under the more accurate restricted elliptic three-body problem hypothesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.