## 2 The \({}^{3}\)ColStar Satellite Mission
### Preliminary Design
#### 2.3.2 Thermal Subsystem
Regarding the temperature determination, the lumped parameter approach considers the entire satellite as a lumped, isothermal system (represented by a single node) with an effective mass and heat capacity. The equations can be found in Appendix C (Equations (A1) and (A2)). To estimate the effective specific heat parameter, a breakdown of each of the satellite's subcomponents was performed, determining their individual mass and heat capacity as is presented in Table 5:  
To evaluate the satellite's thermal performance under extreme conditions, this analysis considers both the worst hot case (WHC) and worst cold case (WCC). The WHC represents the scenario with maximum solar irradiance and minimum heat dissipation, while the WCC considers minimum solar irradiance and maximum heat dissipation. These cases provide a comprehensive understanding of the satellite's thermal behavior under the most challenging environmental conditions. Table 6 presents the parameters considered for each case, including the solar constant, albedo factor, and Earth's effective temperature. \begin{table}
\begin{tabular}{l l l c c c} \hline \hline
**Subsystem** & **Breakdown** & **Material** & **Maximumm Mass** & **Mass Fraction** & **Heat Capacity [J/kg K]** \\ \hline Structure & Ribs & Al 6061 & 24.31 & 1.84\% & 961.2 \\ Structure & Side Frames & Al 6061 & 57.38 & 4.34\% & 961.2 \\ Structure & Kill Switch & Al 6061 & 3.10 & 0.23\% & 961.2 \\ Structure & Thread rod & Al 6061 & 6.06 & 0.46\% & 961.2 \\ Structure & Spacers & Al 6061 & 10.60 & 0.80\% & 961.2 \\ Structure & Screw–Washers–Nuts & Al 6061 & 16.00 & 1.21\% & 961.2 \\ \hline Payload & MINIPIX TPX3 & PCB & 45.10 & 3.41\% & 1544.0 \\ Payload & Control moment gyroscope (CMG) & Steel & 136.50 & 10.32\% & 500.0 \\ Payload & Nano-SSOC-A60 analog sun sensor & PCB & 4.07 & 0.31\% & 1544.0 \\ Payload & Space weather & PCB & 3.30 & 0.25\% & 1544.0 \\ \hline OBC & Mainboard & PCB & 103.40 & 7.82\% & 1544.0 \\ OBC & Daughter Board & PCB & 6.60 & 0.50\% & 1544.0 \\ \hline EPS & MainBoard & PCB & 18.00 & 1.36\% & 1544.0 \\ EPS & Battery Pack & Li-Po & 184.00 & 13.91\% & 1350.0 \\ EPS & PCB +X & PCB & 77.00 & 5.82\% & 1544.0 \\ EPS & PCB \(-\)X & PCB & 77.00 & 5.82\% & 1544.0 \\ EPS & PCB +Y & PCB & 55.00 & 4.16\% & 1544.0 \\ EPS & PCB \(-\)Y & PCB & 55.00 & 4.16\% & 1544.0 \\ EPS & PCB +Z & PCB & 38.50 & 2.91\% & 1544.0 \\ \hline ADCS & MainBoard & PCB & 24.00 & 1.81\% & 1544.0 \\ ADCS & Magnetorquers & PCB & 130.00 & 9.83\% & 1544.0 \\ \hline COMM & Tranceiver - IOT & PCB & 85.60 & 6.47\% & 1544.0 \\ COMM & Antenna System & PCB & 107.00 & 8.09\% & 1544.00 \\ \hline Total & & & 1322.53 & 100\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Thermal breakdown for effective heat capacity determination. Table 7 presents the thermal requirements for each subsystem of the satellite. This allows us to ensure that each component operates within its specified temperature. The thermal analysis results, shown in the accompanying graph, demonstrate the satellite's temperature behavior under both the WHC and WCC scenarios (Figure 6). As indicated in the graph, the satellite's temperature remains within the acceptable operating limits for all components, never exceeding the established thresholds outlined in Table 7.  
These results show that the proposed thermal design effectively addresses the extreme thermal conditions encountered in orbit. However, it is important to emphasize that this analysis is preliminary and further detailed design analysis is crucial to refine the thermal control system and ensure long-term reliable performance.