## 4 Tests  
### Ground Tests  
To ensure the accuracy of the results of the optimized design, the low-orbit communication test satellite underwent a thermal deformation test. Theodolite calibration is used to measure the angle shift between the laser communication load prisms and the star sensor. It is challenging to implement real-time regulation and protection of Theodolite equipment in a vacuum tank due to testing conditions. Hence, by heating the satellite temperature hauled up under the ambient temperature of 20 \({}^{\circ}\)C in the ground atmosphere backdrop, the effect of thermal deformation on prism angle fluctuation between the star sensor and laser communication burden is determined. The results can still be utilized to assess the effectiveness of design and optimization even though the distribution of the temperature field in the ground environment differs from that of the satellite in orbit. We set up three ground-test schemes to judge the effectiveness of the optimized design. In test scheme 1, no optimized support was used. The laser communication load and star sensor were directly installed on the honeycomb panel of the satellite structure. The on-board equipment was opened according to the high temperature conditions in orbit, and the temperature of the satellite structure was increased by this temperature pull-up method. In test scheme 2, optimized support is adopted, and the laser communication load and star sensor are directly installed on the optimized support. A flexible isolation device is used to connect the optimized support and satellite, and the heating mode is the same as that of test scheme 1. The installation mode of test scheme 3 is the same as that of test scheme 2. In addition to the heating mode adopting the same working mode of equipment under high temperature conditions as that of schemes 1 and 2, all heating belts on the satellite are also turned on to maximum pull-up satellite structure temperature and test the ultimate capacity of the optimization effect of the satellite support. The purpose of setting test scheme 3 is mainly because the temperature distribution in the ground test is quite different from the actual distribution in orbit. Therefore, the problem of insufficient verification in the ground test is solved by the maximum pulling up of the satellite temperature field. Table 11 shows the temperature telemetry data of some equipment in the three ground test schemes. The temperature of test scheme 1 and test scheme 2 is similar, so it can be considered that the difference between them is caused by the support optimization scheme. The calibration site is shown in Figure 23. Theodolites A and B are used to target the star-sensor prism, and theodolites C and D are used to target the laser communication payload prism. \begin{table}
\begin{tabular}{c c c c} \hline
**ID** & **Satellite Equipment** & **Test Scheme 1/\({}^{\circ}\)C** & **Test Scheme 2/\({}^{\circ}\)C** & **Test Scheme 3/\({}^{\circ}\)C** \\ \hline
1 & +Y lithium battery & 31.15 & 30.68 & 33.97 \\
2 & \(-\)Z Microwave transceiver channel & 41.34 & 40.14 & 48.03 \\
3 & \(-\)X power amplifier & 52.63 & 51.32 & 55.28 \\
4 & Measurement and control transponder & 41.75 & 40.85 & 44.62 \\
5 & Measurement and control random access terminal & 44.69 & 43.72 & 47.39 \\
6 & Electric push controller & 39.40 & 39.51 & 48.53 \\
7 & Central computer & 42.58 & 41.22 & 50.40 \\
8 & Fiber-optic gyroscope & 40.17 & 38.84 & 44.92 \\
9 & Flywheel 1 & 39.81 & 38.28 & 45.60 \\
10 & High stability clock source & 46.24 & 45.15 & 49.79 \\
11 & Interplanetary link channel & 44.04 & 42.57 & 46.18 \\
12 & Power controller & 43.60 & 42.50 & 49.49 \\
13 & Laser communication load electronics box & 40.97 & 40.09 & 43.61 \\
14 & Phased array transceiver antenna 1 & 44.99 & 41.26 & 56.00 \\
15 & Phased array transceiver antenna 2 & 46.35 & 45.87 & 57.97 \\ \hline \end{tabular}
\end{table} 
Table 11: Temperature data in the 3 ground test schemes. Table 12 shows the calibration results of the prism.