森 治

The 29th Workshop on JAXA Astrodynamics and Flight Mechanics 2019 (July 22-23, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

The 29th Workshop on JAXA Astrodynamics and Flight Mechanics 2019 (July 22-23, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved. As an innovative spacecraft system, a transformable spacecraft is proposed, which is composed of many form elements coupled with each other by an internal force actuator and capable of transferring the form to each other. Herewith, in addition to being able to switch the function of the spacecraft largely by changing its form on orbit, it is possible to control attitude without propulsion using nonholonomic properties and internal force. Moreover, not only the function of the transformable structural spacecraft can be changed by the change of shape, but also various characteristics caused by the shape can be changed on orbit. Thermal characteristics, structural characteristics, etc. can be cited, but if these are actively utilized, characteristics suitable for the mission on orbit can be selected. In this research, focusing on thermal characteristics, we consider changes in thermal characteristics due to shape changes. In general spacecraft, thermal control is carried out by changing the attitude or by using a heater. However, if a transformable structure is used, it is possible to passively cool and heat a specific part of the spacecraft due to a change in the thermal environment by the construction of a heat shield plate or the like. On the other hand, since it is coupled with other characteristics such as structure, it is also necessary to consider the trade-off when considering the entire system. As an example, the transformer under consideration in JAXA has an infrared telescope that needs cooling as a mission equipment, and we considered applying thermal design that makes use of a transformable structure to mission equipment. By blocking sunlight by the panel against the mission unit, thermal control becomes possible without changing the attitude of the mission unit, so that the flexibility of the mission can be improved. Therefore, the purpose of this study is to evaluate the relation between the panel shape of the transformable spacecraft and the thermal environment of the mission part by thermal analysis and obtain the guideline of the panel form suitable for observation mode. From the relationship, we clarify conditions such as the number of panels and arrangement of the transformable structural spacecraft to realize the demand of the thermal environment of the mission section and propose a system design method of the transformable structural spacecraft considering thermal characteristics. In addition, we propose a system design method of transformable spacecraft considering characteristics other than thermal characteristics.

© 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This paper addresses how to design bonding area of the thin-film solar cell attached large space membrane structure. The solar cell glued membrane is easily deformed by the temperature change because of the thermal expansion mismatch between the solar cell the adhesive layer which decreases the power generation efficiency of the solar cell. On the other hand enough bonding area is required to have enough strength under deployment load condition. Thus an optimum bonding area design is examined by using FEA for a single unit of solar cell for OKEANOS membrane. The results of the analyses indicate that the above requirements can be satisfied by employing discreetly located bonding area with having curvature directionality. The obtained design is applied to the OKEANOS membrane where the deformed shape of the membrane with curved solar cell is obtained by FEA. As the results the membrane shape satisfies the requirements thus the effectiveness of the bonding area design is indicated.