Mars500 crew during the 105-day study. The crew will remain in the habitat at the Institute of Biomedical Problems (IBMP) until mid-July. The crewmembers act as subjects in scientific investigations to assess the effect of isolation on various psychological and physiological aspects, such as stress, hormone regulation and immunity, sleep quality, mood and the effectiveness of dietary supplements. The 105-day study precedes a full simulation of a mission to Mars, due to start late in 2009. This will see another six-member crew sealed in the same chamber to experience a complete 520-day Mars mission simulation.