Micro-vibrations exert detrimental effects on spacecraft that requires extreme precision performance. Dynamic mass method (DMM) is a component-level grounded micro-vibration measurement method, which is widely used in the analysis of coupled interplay between micro-vibration sources and spacecraft. However, this study reveals that all existing research involving DMM contains a fundamental error during its theoretical derivation. In light of this, the root cause of the error is investigated based on the mechanical impedance theory. Building upon this, a modified dynamic mass method (MDMM) is further proposed, and corresponding solution steps are also given, with emphasis on the treatment of gyroscopic effects of reaction wheels (RWs). To validate this analytical method, a grounded micro-vibration measurement system for RWs is designed and established. Micro-vibrations of an RW are measured under both the rigid-mounted and isolated conditions, respectively. Leveraging the physical parameters of the isolator, MDMM is applied to process the micro-vibration data measured under a rigid-mounted condition, which predicts the transmitted data under an isolated condition. The analytical data produced by MDMM agrees well with the measured results, which partially validates the feasibility and effectiveness of the proposed MDMM. This analytical method proposed in this work can serve as a theoretical tool for both measurement and analysis of the coupled micro-vibrations of sources and spacecraft.

The optical surface error of the space telescopes plays a decisive role in the image quality. As a key structural component supporting large-aperture optical payloads, the elastic response of the truss support structure under micro-vibration disturbances significantly affects wavefront quality. The paper focuses on a typical segmented primary mirror system and constructs a parameterized model of the truss support structure. The dynamic response of the structure under micro-vibration is systematically analyzed, and the resulting mirror surface deformation is reconstructed using Zernike polynomials. The results demonstrate that the structure exhibits highly localized dynamic responses at specific modal frequencies, which in turn induce optical aberrations, including low-order astigmatism and high-order coma. These findings demonstrate the high sensitivity of the truss structure to micro-vibration. The study elucidates the coupling relationship between structural dynamics and optical performance, providing theoretical support for structural optimization and vibration suppression in high-precision imaging systems.