HUMAN LOCOMOTION AND WORKLOAD FOR SIMULATED LUNAR AND MARTIAN ENVIRONMENTS

Human locomotion in simulated lunar and Martian environments is invest igated. A unique human-rated underwater treadmill and an adjustable ba llasting harness simulate partial gravity in order to better understan d how gravity determines the biomechanics and energetics of human loco motion. This study has two research aspects, biomechanics and energeti cs. The fundamental biomechanics measurements are continuously recorde d vertical forces as exerted by subjects of the treadmill which is ins trumented with a force platform. Experimental results indicate that pe ak vertical force and stride frequency decrease as the gravity level i s reduced. Foot contact time is independent of gravity level. Oxygen u ptake measurements, VO2, constitute the energetics, or workload, data for this study. As theory predicts, locomotion energy requirements for lunar (1/6-g) and Martian (3/8-g) gravity levels are significantly le ss than at 1-g. The observed variation in workload with gravity level is nonmonotonic, however, in over half the subject population. The hyp othesis is offered that energy expenditure increases for lunar, as com pared with Martian, locomotion due to the subject ''wasting energy'' f or stability and posture control in simulated lunar gravity. Biomechan ics data could influence advanced spacesuit design and planetary habit at design, while workload data will help define oxygen requirements fo r planetary life support systems.