Lunar lander trajectory control using model predictive on–off thruster control

With increasing global initiatives in space exploration, including the Artemis lunar exploration and numerous Martian missions, autonomous and accurate planetary landings have become a growing technological challenge. Although historical lunar landings have tolerated large positional errors, advancements in high-accuracy lunar orbital satellite data and the demand for the exploration of valuable sites that are often close to hazardous areas have shifted the focus toward precise landing strategies. For a high-precision landing, the terminal-descent phase is critical, and precise control is crucial for a safe landing. To address this requirement, a novel approach based on discrete model predictive control (MPC) is proposed to achieve precise spacecraft landing during the terminal-descent phase of a lunar mission. The proposed method involves optimizing the binary on–off control inputs for the main thruster and reaction control system of a spacecraft. Unlike conventional MPC approaches that approximate control inputs as continuous variables, the proposed approach handles the constraints of binary on–off actuators directly via combinatorial optimization techniques to ensure an accurate final descent. Simulation results demonstrate the effectiveness of this method, which can significantly enhance the accuracy of lunar landings in future missions.