Design and Analysis of a Composite Satellite Bus for VLEO Applications

The increasing interest in Very Low Earth Orbit (VLEO) missions has highlighted the need for lightweight satellite structures capable of withstanding demanding launch and operational environments. The main objective of this research focused on the development and structural validation, by finite element method (FEM) analysis, of a composite dominated microsatellite bus architecture suitable for VLEO applications, contributing to future certification activities within a European launch.
The proposed satellite bus adopts a cubic configuration and was based on composite sandwich side panels with aluminium honeycomb cores, combined with a unidirectional (UD) composite frame that acts as the primary load-carrying structure. The resulting microsatellite has a total mass of approximately 85 kg, with 35 kg corresponding to the structural mass. Mechanical interfaces between panels and frame were implemented through bolted joints and inserts integrated into the UD frame. Due to the sensitivity of composite materials to atomic oxygen and other environmental effects in VLEO, a protective surface coating was proposed. Key subsystems relevant to an Earth observation mission were defined, and their representative masses were included in the structural analyses.
Structural performance was assessed using FEM-based modal, quasi-static, harmonic response, and random vibration analyses, in accordance with the requirements of a European rideshare launch service. A failure analysis considering the launcher guidelines was performed to identify critical regions of the structure and potential stiffness improvements., achieving promising outputs on majority of the components. The results indicated that, despite the current low Technology Readiness Level (TRL), the proposed methodology for composite-dominated microsatellite bus is structurally viable and can be further developed towards higher TRL, supporting the increased use of composite structures in future VLEO satellite missions.