The Space Station Freedom evolution-phase: Crew-EVA demand for robotic substitution by task primitive

Space Station Freedom represents a significant demand for automation and robotics services as substitutes for crew-performed extravehicular activities (crew-EVA). Results are reported from a study aimed at identifying this demand for crew-performed activities and the crew-task primitive distributions derived for input to future robotic substitution studies. Generic EVA tasks are developed from historical EVA mission timelines, and a set of 70 task primitives defined. The generic task activities are partitioned into task setup, kernel, and tear-down, with standardized task times and frequencies. These standardized times are coupled with inputs from numerous mission databases in a probablistic simulation to obtain estimates of total crew-EVA task time demand by crew task primitive. The use of probablistic model is found to be crucial for understanding, isolating, and addressing the large uncertainties in the EVA task kernels