ESA-selected Mars500 participants Cyrille Fournier (left) and Oliver Knickel (right) prepare to enter the isolation facility on 31 March 2009. Together with four Russian crewmembers, Fournier and Knickel will remain in the habitat at the Institute of Biomedical Problems (IBMP) until mid-July. During their stay, the crew will experience all aspects of a mission to the Red Planet, including launch, the outward journey, arrival at Mars and, after an excursion to the surface, the long journey home. The crewmembers will act as subjects in scientific investigations to assess the effect that isolation has 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.