Long duration manned space flight systems considerations

The systems engineering process must be executed within the constraints imposed by the system environment (including the social, technical, economic, and political (STEP) factors) as well as those imposed by the personnel who will operate and maintain the system. These constraints can sometimes create interdisciplinary, systems issues which will influence the optimization of the interfaces between humans and equipment in the spacecraft system. Also, the synergistic relationships of these issues can sometimes intensify their ultimate effect on the system.

The duration of the mission, in conjunction with the isolation and confinement of the crew, indicate that the spacecraft's social environment and the capabilities and limitations of the crew will be critical to the success of a long duration spacecraft system and must be considered in the crew selection and training criteria, as a part of the system design and development activities.

The design and development process could be improved if the diverse sociological and psychological theories were integrated. A rudimentary Crew/System Interactions Model (CSIM) is proposed which would provide a tool for synthesizing and linking the various theories. The CSIM would serve as a focal point for experts to improve/refine the theoretical causal relationships describing the effects of crew actions and behaviors on the performance of the system.

A systems perspective must be developed throughout the system life-cycle, especially in the crew who will operate and maintain the spacecraft. This perspective can be enhanced through training to identify inaccuracies in the individual's mental model of the spacecraft system. The STEP issues and personnel factors impose constraints on the system design and development activities, encouraging the compartmentalization of the various phases of the life-cycle process, and increase resistance to change, which can make a systems perspective impossible to achieve. The proper consideration of these constraints is therefore crucial to the success of systems engineering.