Mars Sample Return Terminal Rendezvous State-Based Fault Protection

Rendezvous and proximity operations have been extensively exercised in Earth orbit; however, for interplanetary missions additional challenges exist. Communication delays introduce the need for a high level of autonomy and fault protection. The Mars Sample Return campaign involves collecting geological samples on the surface of Mars and launching a small sample container into orbit for autonomous rendezvous and capture by a sample return orbiter. The multimission sample return campaign relies critically on this autonomous event, implying the need for robust fault protection. This study applies a state-based fault protection methodology to autonomous terminal rendezvous of the orbiter and the orbiting sample container. A state machine architecture provides an intuitive visual template for modeling the rendezvous process and detecting, diagnosing, and responding to spacecraft faults in real time. Six different terminal rendezvous scenarios are evaluated, demonstrating the ability of the architecture to properly evaluate fault detection and diagnosis and to respond appropriately based on the current state of the rendezvous process.