Computing-feasibility study of NASA nutrition requirements as applied to a bioregenerative life support system

Abstract

In view of previous studies, a list of 46 foods designated for use in bioregenerative life support system was composed. With the help of a computer program, daily sets of foods of plant and animal origin were compiled from the list of foods. The objective function of modeling was intended to minimize the discrepancy between the calculated values of nutrients in daily food sets and NASA nutrition requirements for long-duration missions. The independent variables in the model were the masses of foods restricted by the lower and upper bounds.It was established that a food set is able to comprise 10-46 foods with violation of the NASA nutrition requirements for iron, vitamin B5 and vitamin D daily intakes. Inclusion of 9 foods in a set resulted in a further violation of the NASA standards concerning saturated fat. As the number of foods in a set has increased from 10 to 22, the objective function decreased from 1.0736 to 1.0332, followed by a gradual increase to 1.1233, when the maximum number of foods was selected from the list of foods.The source of uncertainty in the interpretation of modeling results are the standard NASA intakes of magnesium, potassium, zinc, manganese, vitamin C, thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, vitamin E, vitamin K and n-6 fatty acids, given as exact values.Varying the nutrient content of food sets did not significantly affect the value of the objective function. However, some solutions were infeasible, due to the violation of the NASA standard concerning saturated fat. Also, there were food sets in which the scores of sulfur-containing amino acids and threonine were below 100. In order to reliably maintain the scores of essential amino acids above 100 in a food set, it is necessary to maintain a mass ratio of “animal protein/total protein” equal to 2/3 in accordance with the requirement of NASA.