## 2 Micro-Vibration Test Scheme  
As shown in Figure 1, the micro-vibration test platform proposed in this paper is composed of the light source, dot target, collimator, HPSOP, satellite platform, and AQZSSDs. The light source, dot target, and collimator are installed on the adjustment platforms to provide parallel light simulating deep space target incidents on the optical payload, where adjustment platforms 1 and 2 are used to align the light source with the collimator and ensure that the light emitted by the collimator is incident on the optical payload in parallel. To minimize the impact of micro-vibrations from other moving parts and maximize the observation field, the optical payload is installed at the top center of the satellite platform via three BVILs. During the launch phase, the isolation struts are locked with the satellite platform through frangible bolts to prevent damage to the precision optical equipment caused by random vibrations and shocks. After entering orbit, the frangible bolts are exploded to ensure the execution of the payload observation imaging or laser communication mission. The FSM control system and the image acquisition system within the optical payload are used to decrease LOS jitter and acquire the image point coordinates of the incident light focused on the charge-coupled device (CCD), respectively. Additionally, CMGs and cryocoolers on the satellite platform generate micro-vibration disturbances to the optical payload when they are working. According to Equation (1), the vibration equation of the multi-degree-of-freedom damping system, it is necessary to introduce an AQZSSD to reduce the disturbances caused by the unloading equipment since the frequency range of micro-vibration is 0.01 Hz to kHz [24]. \[M\ddot{x}+C\dot{x}+Kx=0 \tag{1}\]  
As shown in Figure 2, the AQZSSD1 and AQZSSD2 proposed in this paper are used for gravity unloading and horizontal alignment adjusting of the satellite platform and HPSOP, respectively. Each device includes a crane hitch, a sling, a spreader, an adjustable elastic cord set, and a connecting fixture. Notably, the adjustable elastic cord set contains a linear motor, a dynamometer (Type: LH-S02, Liheng Sensing Technology Co., Ltd. in Shanghai, China), and a set of elastic ropes. The connecting fixtures connect the optical payload and the satellite platform to the adjustable elastic cord set through screws and lifting rings to achieve gravity unloading without deformation. The adjustable elastic cord set driven by the linear motors is connected to the connecting fixture through a hook to ensure precise adjustment. The feedback values of the four dynamometers here are indicators for evaluating whether the gravity is unloaded. The crane hook above the AQZSSD lifts the center ring of the sling to bear the gravity of the system to be tested and the suspension tool. Figure 1: Micro-vibration test platform. Figure 2: AQZSSD of the (**a**) satellite platform and the (**b**) optical payload. Before the test, the gravity of the satellite platform and the optical payload were unloaded through the AQZSSD, and the parallelism and position of the optical payload were adjusted in sequence. The detailed automatic adjustment mechanism based on AQZSSD is presented as follows (Figure 3): Step 1, to unload the payload's gravity, make parallel adjustments to the linear motors until the dynamometer value \(F_{D}\) is equal to the payload gravity \(G_{P}\); Step 2, to prevent imbalance caused by different deformations among the elastic ropes, adjust each linear motor independently until the theodolite measured value \(\theta_{m}\) is smaller than the parallelism tolerance \(\theta_{t}\); Step 3, to avoid material creep and relaxation of the suspension ropes during experiments, take stress relaxation; and Step 4, to achieve precise alignment and installation of optical payloads and satellite platforms, adjust the crane until the laser rangefinder measure T\({}_{m}\) is equal to the position tolerance T\({}_{t}\).