During self-rescue operations with the NASA Simplified Aid for Extra-Vehicular Activity(EVA) Rescue (SAFER), astronauts operate under a tight fuel constraint, and have finitebattery and oxygen consumables for a return to the International Space Station (ISS). Thereis limited system state feedback to the astronaut during SAFER training simulations andoperations, and typically mission performance is categorized as a safe return or not. Real-time performance monitoring, which is currently lacking in this system, can be used toprovide a comprehensive assessment of an astronaut’s state and mission performance. Thisalso provides valuable real-time diagnostics for evaluating detailed performance successesand failures. Several real-time performance metrics, including flight performance,workload, and situation awareness were developed to quantify combined astronaut-SAFERperformance during a simulated self-rescue task. Flight performance is quantified bycomparing the pilot’s current trajectory with a baseline trajectory. The baseline trajectoriesare fuel-optimal paths for each unique flight time that consider the astronaut’s initialposition and velocity with respect to the ISS; the trajectories use a single-impulse delta-Vand exploit the relative orbit dynamics of the system. Workload is estimated by computingthe response time to a two-choice secondary task, which is a proxy for an operationalcommunications response task. Situation awareness is estimated by scoring verbal callouts ofkey SAFER states based on correctness and response time. The development and validationof these real-time performance metrics has applications toward increasing operational safetythrough early identification of critical performance decrements, and can be used to supportthe development of improved SAFER self-rescue trajectories and fuel-optimal trainingprotocols.
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