Carbon Flow in an Artificial Ecosystem Comprised of Crew, Goats and Crops for Three 1-Week Confined Habitation Experiments Using CEEF

Three 1-week experiments were conducted from September to October of 2005 in which two human subjects called as eco-nauts were enclosed and worked in an airtight facility called Closed Ecosystem Experiment Facilities (CEEF). The test involved connecting a Plant Module (PM) with 23 crops, including rice, soybean, peanut, and sugar beet, to an Animal & Habitation Module (AHM), which included the eco-nauts and two Shiba goats. Although only 34% (by weight) of the food consumed by the eco-nauts was produced by crops in the PM in the first experiment, it was 81% in the second and third experiments. As for feed for the goats, although all was Timothy hay was supplied from outside in the first experiment, all of the feed (rice straw, soybean leaf and peanut shell) was produced in the PM in the second and third experiments. In all these experiments, the crops produced more oxygen than the amount consumed by respiration of human and animals. The oxygen build-up in the atmosphere of the PM from crop photosynthesis was separated and supplied to the atmosphere of the AHM. Carbon dioxide build-up in the AHM atmosphere from respiration of eco-nauts and Shiba goats was separated and supplied back to atmosphere of the PM. Carbon in waste except for a part of that in human feces was withdrawn and not recycled for these experiments. Therefore, extra carbon dioxide was added to the PM atmosphere in order to compensate for the demand from photosynthesis of the crops. Amounts of carbon in edible and inedible parts of harvested crop biomass and amount of carbon taken by the eco-nauts and Shiba goats were also estimated.