Critical issues for space life sciences

Human exploration of space requires the interaction of three general systems: environmental health and life support systems, countermeasure systems, and medical care systems. These systems address atmospheric pressure, uncertainties associated with space radiation, the potential for exposure to toxic materials in the closed environment, spacecraft habitability, human physiology, and microgrvaity. While these interdependent systems serve the same overall goal -- the protection of the human crewmember from the hostile space environment -- each has specific essential roles. Individually and in combination the three systems should be responsive to a strategy of risk reduction, so that the scientific possibilities of exploration missions may be maximized.