BBC: The third and final stage of the 520-day Mars500 experiment has concluded, with all six members of its international crew in good health. The experiment was conducted to gather data on the physiological and psychological effects of the extended isolation involved in a flight to Mars. The crew lived and worked in a mockup windowless spacecraft and had limited contact with the outside world; to simulate the actual communications lag between Mars and Earth, a time delay of up to 25 minutes was imposed on all communications. The crew’s hormone levels, sleep patterns, and moods were monitored. Tentative discussions have begun between the partners of the International Space Station about doing an isolation experiment in orbit.