高尾 勇輝

In upcoming missions to the moon, transporting as much payload as possible within a limited timeframe is a critical challenge. However, identifying an optimal spacecraft system design is complex due to the interdependence of multiple subsystems, each requiring distinct design methodologies. Multidisciplinary design optimization (MDO), which concurrently evaluates various disciplines to identify an optimal design, presents a promising solution. Most existing research on MDO focuses on aircraft, launch vehicles, and Earth-orbiting satellites. In contrast, missions to cislunar space and beyond involve numerous candidate trajectories with varying geometries, significantly influencing spacecraft system design. This paper introduces a multidisciplinary system design optimization technique specifically for lunar transport missions using electric propulsion. A lunar transfer trajectory optimization problem is formulated that incorporates spacecraft design parameters. A surrogate model is developed to predict transportation performance based on these design parameters. By employing the surrogate model, an optimal system design is achieved that maximizes payload mass while minimizing flight time. The results elucidate the structure of the solution space for the spacecraft system design problem, enabling the automatic identification of feasible and optimal designs.

This paper proposes a new methodology for solar-sail attitude control that uses only momentum wheels. Different from conventional solar sails packaged in a central hub, the sailcraft is deployed in the direction of one side of the storage. In this single-wing configuration, the offset between the center of mass (c.m.) and center of pressure (c.p.) is large and lies in the sail plane. When specular reflection is dominant, solar-radiation-pressure (SRP) force vector points in the out-of-plane direction, thus causing an in-plane SRP torque orthogonal to the c.m./c.p. offset vector. Therefore, by placing a bias momentum in the c.m./c.p. direction, the sailcraft keeps rotating in the same plane while maintaining its orientation relative to the sun. Analysis reveals that the attitude motion of the one-winged momentum-biased solar sail is basically unstable, but the system can be stabilized in a neutral manner through minor control of the bias momentum. Furthermore, adding another control moment in the out-of-plane direction enables asymptotic stability. Control in the remaining in-plane direction makes it possible to avoid wheel saturation. Numerical simulations demonstrate that both attitude maintenance and maneuver can be performed and that the controller is robust to parameter errors.