Fuel-Efficient Descent and Landing Guidance Logic for a Safe Lunar Touchdown

摘要: The landing of a crewed lunar lander on the surface Moon will be climax any mission. At touchdown, mechanism must absorb load imparted due to vertical component lander’s touchdown velocity. A large horizontal velocity also avoided because it could cause tip over, risking life crew. To conservative, worst-case is always assumed in designing mechanism, making very heavy. Fuel-optimal guidance algorithms for soft planetary have been studied extensively. In most these studies, constrained with zero With bounds imposed magnitude engine thrust, optimal control solutions typically “bang-bang” thrust profile: “bangs” instantaneously between its maximum and minimum magnitudes. But descent might not able throttle extremes instantaneously. There concern about acceptability our study, formulated cost function that penalizes both fuel engine. this formulation, there requirement achieve Only consistent capability gear design required. Also, since nominal level terminal sub-phase well below peak no bound used problem. Instead bang-bang type solution, generated continuous time. we can easily derive analytical expressions vector, components, other system variables. These provide insights into “physics” maneuver. help engineers better “balance” conflicting needs achieving safe velocity, low-weight low cost, goals. comparing computed results preflight trajectory Apollo-11 mission, noted interesting similarities their performance.