Space Food System Water Content: Considerations for ECLSS Water System Closure



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50th International Conference on Environmental Systems


The water content of the food system has a direct impact on determining an efficient level of water system closure in the Environmental Control and Life Support System (ECLSS) on a spaceflight mission. The standard food system, which makes up the bulk of the food on the International Space Station (ISS), consists of a variety of shelf stable foods that are provisioned to meet nutritional requirements. In this work, we developed a tool to estimate water content within the standard food system, given varying usage rates. Outcomes from this tool indicate that, as provisioned and with a predicted consumption rate that meets nutritional requirements, approximately 46% of the current standard food system is water. Around 88% of the water content in the food system was determined to be in the retort thermostabilized foods. Recent mission analysis has indicated it is beneficial to life support processing to reduce the water content to 30%. With the assumptions used in this analysis, approximately 37% of the retort thermostabilized foods (ready-to-eat, fully hydrated at launch) would need to be replaced with freeze-dried foods to meet this goal. The feasibility of developing a similar nutritional variety of acceptable and stable freeze-dried foods to replace this percentage of thermostabilized foods is currently unknown. Some foods are not as compatible with freeze-drying, and consideration must be given for provisioning balanced macro and micro-nutrition, variety, and acceptability, in addition to water content. ISS crew members have commented that the variety from different types of foods is important to prevent menu fatigue and maintain intake, health and performance. The ready-to-eat, fully hydrated foods are especially critical when crew time is limited. The impact of reducing these options on overall intake and resulting health and performance is currently unknown and would need to be assessed.


Grace Douglas, NASA
James Broyan, NASA
Meredith Johnson, JES Tech
ICES502: Space Architecture
The 50th International Conference on Environmental Systems was held virtually on 12 July 2021 through 14 July 2021.


food system water content, water system closure, menu fatigue, nutrition