Execution of scientific objectives such as to investigate the central peaks of a big crater of the moon is thought to be the most scientifically interesting. Precise and safe autonomous landing ability is a productive issue for this investigation. Here it is proposed a scheme of trajectory generation for lunar descent. This research includes a sketch of a qualitative scheme on solutions of motion control equations for lunar descent vehicle from orbital speed condition down to the terminal descent situation. A trajectory generation algorithm is developed accumulating more than one step with variable thrust to mass ratio. Mathematical modeling, algorithm design, simulations and results are presented in this paper. In fact, the proposed trajectory generation scheme can readily be used to develop real-time guidance algorithm for future precise and safe lunar landing missions reducing the computational burden.

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This paper addresses a elasto-plastic behavior of creasing process for a z-fold membrane to examine the mechanical properties of the crease, which determine the folding and deployment characteristics of a large membrane. To examine the elasto-plastic behavior in terms of the layer pitch and the contact force for creasing the membrane, fold experiments are performed. The experimental results are evaluated numerically by demonstrating elasto-plastic FEM analyses, and examined theoretically by introducing a mathematical model. In the FEM analyses, the precision is improved by investigating numerical parameters; the penalty stiffness for the contact analyses, the numerical damping in the equilibrium equation, and the size of the finite element mesh, which are dominant parameters in non-linear FEM analyses. In the mathematical model, the mechanics of the creasing process is formulated for elastic deformation. These results indicate that the loading process of the creasing properties is confirmed in terms of the contact force and the layer pitch. On the other hand, the further examinations are requested for the unloading behavior to determine the mechanical properties of the crease precisely.

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