Verification of Thermal Design for Small Satellite Izanagi with Synthetic Aperture Radar using Measured Flight Data

抄録

In this study, the thermal model developed to design the small satellite Izanagi was verified using flight data. Izanagi is a 100 kg class Earth observation satellite equipped with a synthetic aperture radar, which was put into orbit in December 2019. Flight data, including attitude, power/consumption, and temperature measurements, were collected from 8:16 to 18:36 (UTC) on August 20, 2020. The recorded temperatures were compared with those predicted by the thermal mathematical model, which was developed using Thermal Desktop/SINDA/FLUINT and reproduces the thermal condition in the relevant time with the two-line element and design data. The results revealed that all the onboard devices fluctuated within the allowable temperature range. However, there was a difference between the thermal mathematical model and the flight data temperatures. The maximum temperature difference was observed in the power control unit, and the average temperature difference was approximately 20 °C. Therefore, based on the flight data, modifications to the model were considered in terms of power generation, internal heating, surface optical properties, number of nodes, and temperature measurement points. Consequently, the difference in average temperature between the thermal mathematical model predictions and the measured flight data decreased from 11.7 °C to 3.1 °C.