The increasing complexity of modern space missions, particularly those involving long-duration habitable modules, is pushing traditional federated avionics architectures to their limits. These legacy systems, characterized by dedicated computers for each function and a fragmented mix of low-bandwidth buses, suffer from high mass, complex wiring, and limited scalability, reusability, and in-flight adaptability. This thesis proposes and analyzes a novel crate-based modular avionics architecture designed to address these challenges. The core of the work is the validation of Time-Triggered Ethernet (TTEthernet) as a high-speed and deterministic backbone for inter-crate communication. TTEthernet’s capability to concurrently manage time-triggered, rate-constrained, and best-effort traffic on a single network makes it an ideal candidate to replace legacy bus systems and support mixed-criticality applications that demand higher bandwidth.