expenditure is lost in the resistance inherent to the suit. suited human performance levels when working in partial g environments are not known and represent an additional knowledge gap that must be filled by conduct of appropriate research. in analog environments to develop the needed exercise regimens needed for different mission scenarios, analog environments will be necessary. the appropriate analog environments for optimizing mission-specific exercise prescriptions and exercise hardware are not yet well defined. initially, a lunar analog environment will be necessary to determine if activities of daily life in combination with anticipated surface eva activities will protect skeletal muscle function. the outcome of this study will determine what additional modes, intensities, and volumes of exercise will be needed to maintain skeletal muscle function in a lunar partial g environment. the results of lunar analog studies will be invaluable for the design and planning of a martian outpost mission. exploration mission operational scenarios a mission to mars or another planet or asteroid within the solar system is not beyond possibility within the next two decades. extended transit times to and from distant planetary bodies within the context of current cev designs represents a formidable challenge to the life sciences community. knowledge drawn from experience and research during long-duration microgravity exposure on the iss will be beneficial in mitigating risks to humans during this phase. many gaps in our current knowledge about living and working for long periods on planetary surfaces in partial g environments should be filled during lunar outpost missions.