The Influence of Repeated Closed Habitation Experiments on Crews Health

Two-week closed habitation experiments were repeated three times using Closed Ecology Experiment Facilities (CEEF) to evaluate the capability of advanced life support systems. The CEEF is a two-manned system. Four crew members, termed econauts, inhabited the CEEF, taking turns at one-week shifts in pairs. Each econaut underwent three habitations. In order to evaluate the state of health of the crew, medical examinations were carried out before, immediately after and two months after the series of habitations. Physical data such as blood pressure, body temperature and body weight were monitored during each habitation. In 2005, though calorie intake and expenditure were well balanced, a temporary reduction in body weight was observed. As a countermeasure in 2006, econauts began their habitation diet one week before habitation to adapt their condition. As a result, total serum cholesterol significantly decreased after the series of habitations. Triglyceride and beta-lipoprotein also showed a downward trend. Despite these changes however, no decrease in body weight was found to occur in this study. CEEF and the related procedures created for the habitation are confirmed to sustain two humans for at least 7 days and beyond.