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In unsuited locomotion, running is more energy efficient than walking, per unit distance and mass, when gravity is less than 0.5g. We analyzed past energetics studies to evaluate whether this finding also applies to locomotion in space suits. We found least-squares fits for cost of transport [J·kg−1 · m−1], C, as a function of gravity. Suited C was lower for running at all gravity levels (Earth, Lunar). High suited C during walking likely results from high space suit joint torques; space suit legs, acting as springs during running, achieve low C by improving recovery. Walk-back constraints for planetary extravehicular activity are probably overly conservative and can be reduced to reflect the relative efficiency of running in space suits.

Human explorers of planetary surfaces would benefit greatly from a spacesuit design that facilitates locomotion. To aid in the development of such an extravehicular activity suit, a design effort incorporating the concept of mechanical counter pressure (MCP) was undertaken. Three-dimensional laser scanning of the human body was used to identify the main effects of knee flexion angle on the size and shape of the leg. This laser scanning quantified the changes in shape that must be supported by an MCP garment and the tension that must be developed to produce even MCP. Evaluation of a hybrid-MCP concept using inextensible materials demonstrated strong agreement between experimental data and a mathematical model with rigid cylinder geometry. Testing of a form-fitting garment on the right lower leg of a subject demonstrated successful pressure production. Further research is required to evaluate how evenly pressure can be distributed using the hybrid-MCP concept.