Space Station Crew Safety: Human Factors Model

As NASA prepares plans to develop a space station, one of the current study tasks is of Crew Safety Alternatives. NASA has always been a paradigm of safety consciousness, and recognizes that the space station would be both qualitatively and quantitatively different from previous spacecraft. During the initial phase of this project, it was recognized that the major differences between previous spacecraft such as Apollo, the present shuttle and the space station are the roles of extravehicular activity and human factors. A model of the various human factors issues and interactions that might influence crew safety was developed. The first step addressed systematically the central question: How is this space station different from all other spacecraft? A wide range of possible issues was identified and researched. Five major topics of human factors issues that interact with crew safety resulted: Protocols, Crew Incapacitation, Task Related Issues, Critical Habitability and Personal Choice. Next an interaction model was developed that would show some degree of cause and effect between objective environmental or operational conditions and the creation of potential safety hazards. The intermediary steps between these two extremes of causality were the effects on human performance and the results of degraded or delayed performance. The model contains one stressor/milestone, one human performance milestone and one safety hazard threshold, with two intervening countermeasure points. The first opportunity for intervention is the countermeasure against stress. If this countermeasure fails, performance degrades. The second opportunity for intervention is the countermeasure against error. If this second countermeasure fails, the threshold of a potential safety hazard may be crossed.