Human factors analysis of extravehicular servicing of payloads within the space station servicing facility

A series of studies on extravehicular (EV) servicing of payloads was performed for the space station on-orbit assembly, maintenance, and servicing project at Goddard Space Flight Center (GSFC). The studies covered three types of servicing that could be performed in the space station servicing facility: change-out of orbital replacement units (ORUs), on-orbit assembly, and fluid replenishment. Servicing activities were decomposed into functions, subfunctions, and tasks. The tasks were allocated to EV, intravehicular (IV), and ground personnel. The temporal flow of the tasks was described using the computer-human operational requirements analysis system (CHORAS), an in-house graphic tool that models the role of the human operator in a complex system. Once tasks were defined, detailed analyses were performed to identify the cognitive, sensory, and motor skills, information (data flows), and equipment needed to perform each task. The results of the studies include: a detailed operations concept for space station-based payload servicing, work performance issues, and design recommendations for procedures, equipment, and performance aids