## 3 Results and Discussion
### Effects of Thermal Load Amplitude on Satellite Health  
Figure 7 shows the effects of different thermal load amplitudes on the dynamic temperature of target damaged component. Under normal orbit operation, the temperature range of the temperature controller is 0 to 50. However, under the action of the pulse thermal load, the temperature of the target damaged component rose rapidly and changed periodically. After 10 cycles of thermal loading, the temperature of the damaged component increased cumulatively. This is because the component cooling time caused by the thermal load of 0 is short, resulting in insufficient cooling, which eventually leads to a cumulative increase in temperature. Comparing Case I and Case II, the temperature rise caused by different thermal load amplitude was variant in one operating period. This is because the temperature rise of the same component in the same time interval is positively correlated with the thermal load.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Cases** & **Amplitude** & **Duty Ratio** & **Cycle** \\ \hline I & 2 W/cm\({}^{2}\) & 1/6 (Heat 10 s; Cool 50 s) & 10 \\ II & 4 W/cm\({}^{2}\) & 1/6 (Heat 10 s; Cool 50 s) & 10 \\ III & 2 W/cm\({}^{2}\) & 1/2 (Heat 10 s; Cool 10 s) & 10 \\ IV & 2 W/cm\({}^{2}\) & 1/6 (Heat 10 s; Cool 50 s) & 40 \\ \hline \end{tabular}
\end{table}
Table 3: Thermal damage conditions and value.  
Figure 7: Dynamic temperature of damaged components under Case I and Case II.  
When the heat flux density is 2 W/cm\({}^{2}\) and 4 W/cm\({}^{2}\) respectively, the health degree and failure factors of the satellite subsystems are shown in Figures 8 and 9. As shown in Figures 8a and 9a, the health degree of the satellite's thermal control system is exponentially decreasing, and the health degree of the satellite's payload is also slightly damaged. This is because the thermal damage of the temperature controller component will directly affect the health of the thermal control subsystem. As mentioned earlier, the temperature controller is designed to serve the payload, so when the controller is damaged, the payload health is also affected. As shown in Figures 8b and 9b, the failure factor of the satellite thermal control subsystem increased. According to the definition of failure factor, failure factor is not equal to 0, which means that a component will fail at that time. Therefore, the distribution of the failure factor can determine the speed of failure.  
In order to visually compare and analyze the effects of different thermal load amplitudes on satellite systems, this section mainly discusses the health changes of thermal control subsystems, as shown in Figure 10. Compared with the normal orbital condition, the health of the thermal control system decreased with time, indicating that the health of the subsystem is deteriorated to some extent. Moreover, as the heat flux density increased, the health condition of the thermal control subsystem deteriorated more severely. In Case I, the health degree of the TCS eventually dropped to 0.95; in Case II, the health degree of the TCS eventually fell to 0.936. Moreover, the greater the thermal load, the earlier the system is damaged. This is because the higher the heat load, the higher the temperature of the damaged component, which makes the component more vulnerable to failure.  
Figure 8: Health indicators of satellite subsystems (Case I): (a) Health degree. (b) Failure factor.  
Figure 9: Health indicators of satellite subsystems (Case II): (a) Health degree. (b) Failure factor.