Control of the human environment

The human environment in space is controlled within fairly narrow limits, the range between the limits representing man's ability to adjust without serious strain. Broadly defined, environment includes the makeup of the gaseous artificial atmosphere, gas temperature, movement and humidity, the thermal radiation level, the mechanical force field, and the level of ionizing radiation. From the control standpoint, there is not much to be done about g-forces and radiation. The gaseous atmosphere and the thermal environment offer more opportunity to the control engineer. Biologically speaking, the controllable environment serves two major body functions, respiration and thermoregulation. In the isolated artificial atmosphere of a space cabin the environmental variables which affect these functions are closely interwoven. For example, water vapor pressure and gas movement are involved in both respiratory balance and heat balance. Various approaches to control of the human environment in space will be described. Simple automatic controls in present systems will be discussed. More complex control needs will be suggested for the future systems designed to carry man ever farther into space. No plans have been made to publish this discussion.