Thermal Design and Evaluation of the Microsatellite ALE-1

The Space Robotics Laboratory (SRL) of Tohoku University and ALE Co., Ltd. developed a 60-kg-class microsatellite known as the ALE-1, which was launched in January 2019. The main mission was to generate artificial meteors. To achieve this, the temperature of the ALE-1 on-board components must be strictly maintained within specified ranges of safe operation. This is particularly critical because high power consumption is required for the mission. The purpose of this study is to propose a heat transfer parameter determination method using an experimental equation to calculate the thermal contact conductance. Additionally, to improve the accuracy of the heat transfer parameter determination, a thermal vacuum test was conducted and the experimental equation was calibrated. This study also discusses the significance and necessity of calibrating the experimental equation. Finally, the validity of the heat transfer parameters obtained by the ground test was evaluated by comparison with actual flight data. In the flight data analysis, the change in solar cell absorptivity owing to variations in the battery state-of-charge is also considered. The flight data analysis covers the early orbit entry phase and the period after high power consumption.