ns Engineering 



All of the above factors, and other human factors design requirements, are 

 discussed in the four volumes of Man-Systems Integration Standards (MS1S), issued 

 by NASA in March 1987 as NASA-STD 3000. This document, which is a 

 significant first step in developing a standardized set of human factors 

 requirements, will be revised as necessary to include additional standards for 

 future manned space activities. It is important to recognize that the MSIS is a 

 compilation of what seems to have worked in the past. As such, it is based 

 largely on experience. The document needs, however, to be enhanced by 

 systematic testing of alternatives to determine the optimum, as is done for the 

 more purely engineering specifications of the spacecraft. In addition, it is vital that 

 instrumentation be available to measure all key aspects of the actual environment 

 so that proper control can be exercised. 



"Crew Factors," the previous discussion, explored the psychological and 

 sociological ramifications of long-duration space flight. A major issue for systems 

 engineers is how to design the environment to enhance the psychological health 

 of the crew. Prolonged periods of confinement and isolation are psychologically 

 damaging if deficiencies exist in the livability or habitability, of the environment. 

 For example, inappropriate noise and vibration levels, inadequate water and food 

 systems, privacy constraints, recreation activities incompatible with crew 

 preferences, and an aesthetically monotonous environment can have a profound 

 influence on the psychological health of individuals in confined and isolated 

 settings (7,8,9). These factors represent potential sources of stress that can lead to 

 low morale, decrements in performance, and an increased vulnerability to illness. 



Food may pose additional problems during space flight. It becomes an increas- 

 ingly important concern, on psychological, physiological, and technological bases, 

 as mission duration lengthens. Nutrition is an important factor in maintaining 

 physiological health. Manipulations of the crew's diet may even be an effective 

 countermeasure for some of the degenerative effects of weightlessness. Beginning 

 with the Space Station, food must be stored for increasing lengths of time, 

 utilizing methods that do not require much space or electric power and that mini- 

 mize system weight and size. There is a logistic penalty for any significant amount 

 of food that is not consumed. 



The food preparation system has to be flexible enough to allow for a variety of 

 alternatives and self-selection and to require minimal preparation time either by 

 one person or the entire crew for individual, special dinners, emergency rations, 

 and group meals. For the Space Station, the best system may be to store food in 

 bulk and prepare meals from ingredients. The important point is that Space 

 Station technology in this area has yet to be developed, as is the case with other 

 areas of habitability including the hygiene and waste management systems. While 

 much work is currently under way on the food preparation system, the efforts 

 must be expanded. Food and food preparation will be a vital factor in the success 

 of any long-term space mission. 



The Space Station represents an opportunity to validate and extend our under- 

 standing of the relationships among habitability factors systematically so that 



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