The hatch of the Mars 500 has closed. From that moment on, the all-male crew, of whom three are from Russia, two Europeans and one from China, will remain in their ground-based "spacecraft" for 520 days.

During the period, the crew members will live in spartan conditions of a mock-up spaceship and follow a harsh regimen of experiments and exercise. But they won't endure the weightlessness in the module. The main task of the Mars 500 is to study effects of long isolation to help a real space crew of the future cope better with stress and fatigue.

The experiment will simulate a 250-day journey to Mars, a 30-day surface exploration phase and 240 days back trip. To imitate the Mars landing, half of the crew will move to a separate module that will be sealed up from the rest of the facility.