Comparison of Thermal Design of Horyu-Series and Results of Thermal Vacuum Testing

This paper describes the thermal design and testing of Horyu-4 to be launched in 2016. Kyushu Institute of Technology (KIT) has been developing nano-satellite since 2006. 2 nano-satellites (Horyu-2) and Shinen-2)) have been launched so far. In 2016, Horyu-4 will be launched by JAXA H2A rocket. Horyu-4 satellite project was started from 2013 and a basic design of Horyu-4 is based on that of Horyu-2 launched in 2012. Horyu-4 is 30cm-cube satellite and its weight is 12 kg. A main mission of Horyu-4 is observation of discharge phenomena on solar cell in space. Main changes from Horyu-2 are (1) increasing in weight with increasing mounted mission components, (2) changing of orbit inclination from 98.1˚ to 51.6˚, and (3) changing of orbit altitude from 680 km to 575 km. The different point in a thermal design of Horyu-2 and 4 from a conventional nano and micro-satellite is a wide temperature fluctuation due to low density. Horyu-4 adopts a passive thermal control. Surface properties of external panels and insulation between internal circuit boards and structure frames were adjusted to ensure acceptable temperature ranges including margin for internal circuit boards. To verify the thermal design and operation of bas system and components, thermal vacuum tests were conducted in each development phase. This paper will explain the detail of Horyu-4’s thermal design comparing with Horyu-2’s design and on-orbit data. In addition, results and testing method for thermal vacuum testing will be reported. Finally, flight prediction data and on-orbit data will be compared.