## 5 Thermal Balance Test of the Deployable Reflector Antenna in STM Phase  
This section deals with the results of the thermal balance test of the STM of the deployable reflector antenna. The thermal balance test of the reflector antenna was conducted in the Dirty Thermal Vacuum Chamber of the Korea Institute of Construction Technology (KICT). This chamber is a lunar surface environment simulator for various tests on the construction environment on the lunar surface, and we decided to use this equipment because the thermal balance test in STM phase does not have any requirement for cleanliness of test facilities. To develop a satellite antenna, a thermal analysis should be performed to evaluate the temperature range of the antenna for the orbital thermal environment and to  
Figure 7: Acoustic load test; (**a**) the required environmental specification and the measured sound pressure level; (**b**) the result of the low-level acoustic random test before and after acoustic load test of the full level; There is no tolerance guideline in the high frequency range for the center frequency of 4 k, 8 kHz (black dashed circle in subfigure (**b**)); (**c**) the result of the low level acoustic random test before/after the acoustic load test; The frequency and amplitude at the 1 st peak frequency is used for the reference of the modal survey (black dashed circle in (**c**)). confirm the thermal stability. To construct the reliable thermal analysis model, the optical properties of the reflector antenna components and the thermal conductivity coefficient between the assembly interfaces should be correlated. First of all, the thermal analysis model is constructed based on the general optical properties and thermal conductivity coefficients. Using this thermal analysis model, thermal analysis of the ground test is numerically performed, and then numerical optimization is performed using the temperature data measured in the thermal balance test. By using numerical optimization to minimize the difference between the temperature data obtained from the test and the results of the thermal analysis, a well-correlated thermal model is constructed. For the model correlation, we use the thermal desktop(r) which is thermal analysis software in Ansys 2023 R2. In this program, the error between the numerically computed and experimentally measured temperature data of each component is minimized based on the reduced order modeling. Using the reduced-order model, computational cost is efficiently reduced, and the reliability of the thermal analysis mode is improved [16; 17]. Figure 8 shows the test configuration and procedure of the thermal balance test to measure the temperature data used for the model correlation. Figure 9 shows the test configuration and the time history of shroud temperature and vacuum pressure during the thermal balance test. As shown in Figure 9a, the STM of the reflector antenna was located in the center of thermal vacuum chamber with a semi-deployed condition during the thermal balance test. Since the temperature data measured by the thermal balance test is used as the reference data for correlating the optical properties and the thermal conductivity of the thermal model for the ground test simulation, it is important to measure the thermal distribution with a clear temperature difference in the cold/hot balance condition. To impose the clearly deferent thermal source, the patch heaters were attached to three of the 24-unit main reflectors, as shown in Figure 9b. For the cold/hot balance conditions, three main reflectors are powered by 550 W and 1650 W respectively. As shown in Figure 9c,d, the thermal equilibrium tests were conducted in a thermal vacuum chamber with the vacuum pressure lower than \(1^{-6}\) torr and shroud temperature lower than \(-196\)\({}^{\circ}\)C, respectively. Except for Phase III that the test was briefly paused, the vacuum pressure and shroud temperature satisfy the test requirements.