Air-Bearing-Based Evaluation of Reaction Wheel Micro-Vibrations and Their Impact on Small Satellite Pointing Stability

High-performance imaging satellite missions require exceptional pointing stability to ensure image quality and geometric fidelity. This stability is often degraded by micro-vibrations originating from reaction wheels, which propagate through the spacecraft structure and induce line-of-sight (LoS) jitter. Although force-torque measurements are commonly used to characterise these disturbances at component level, relating them to spacecraft-level pointing errors remains a key challenge for platform designers. This paper presents an air-bearing-based experimental campaign to directly link reaction-wheel disturbance spectra to satellite pointing stability and to evaluate mitigation strategies.

A four-wheel pyramid reaction-wheel assembly mounted on elastomeric isolators was integrated with a planar air-bearing setup instrumented with a laser-based optical measurement system. Controlled flywheel unbalance conditions were introduced to excite dominant low-frequency disturbance mechanisms. Measured laser-beam displacement and jitter were analysed in the time and frequency domains and compared with analytical disturbance models and simulations to validate predicted LoS responses.

Results confirm that unbalance-related disturbances are the dominant contributor to LoS instability in small, high-resolution imaging satellites and demonstrate the limited effectiveness of passive isolation at low frequencies. The combined modelling, simulation, and air-bearing measurement framework provides a validated method for predicting reaction-wheel-induced micro-vibrations, allocating jitter budgets, and assessing isolation and balancing strategies early in the design cycle of future satellite missions.