Systems Engineering 



within the spacecraft environment that could threaten the health and safety of the 

 crew. Spacecraft materials behavior during long-term habitation, water treatment 

 chemicals, materials processing, and biological and experimental activities increase 

 the probability that contaminants will be released into the closed environment that 

 may ultimately threaten crew health (1). 



Routine monitoring of air and water quality, particularly for trace contaminants, as 

 well as the microbial environment, will be needed beginning with the Space 

 Station. Except for gas composition, however, NASA does not have the requisite 

 technology available. A recent assessment of environmental-monitoring and control 

 requirements has identified deficiencies in the following areas: 



• Buildup of microbial flora on the spacecraft surface and EVA systems 



• Environmental debris in terms of volatile organic compounds, airborne 

 particulate matter, and metals 



• Microorganisms and the buildup of treatment chemicals and leached 

 contaminants in recycled waste water 



• Fire within the spacecraft 



• Vibroacoustics control. 



Real-time monitoring systems, particularly sensors, are required to detect and 

 characterize contamination levels from these factors. All the potential 

 environmental hazards need to be clearly identified and the means for effectively 

 counteracting them need to be developed. Acceptability standards also should be 

 determined. In addition, procedures for maintaining a nontoxic environment need 

 to be developed, and the crew should be trained in implementing these 

 procedures. 



NASA should decide if it needs to develop the environmental-monitoring and 

 decontamination technology itself. The risks involved with using existing 

 technologies on the Space Station need to be clearly evaluated, particularly since it 

 is known that the current instrumentation is marginal. It is critical to understand 

 fully how the environmental quality requirements will change as missions to the 

 Moon and Mars are planned. In addition, it is important to investigate the 

 contingencies required and to establish the responsibilities for managing the 

 needed actions in the event of severe contamination in the spacecraft environ- 

 ment. Cleaning materials constitute another potential source of hazard. A study 

 should be conducted to determine if there are synergistic effects that will be 

 detrimental to crew health. 



Other significant issues to be resolved in maintaining environmental quality 

 include the impact of monitoring tasks on crew performance. Will the available 

 instrument technology require too much of the crew's time? A related issue 

 involves the effective allocation of monitoring tasks between humans and 

 machines. How can we build systems to compensate for complacency errors? 



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