Six men are locked inside a tubular building in Moscow for 520 days, pretending to be on the long trip to Mars.

Like the earlier Biosphere 2 program, once inside the crew stays inside for the duration. (But unlike Biosphere 2, food and air are added and wastes removed.)

It’s an international staff: three Russian, two Euros, and one Chinese, a joint effort between the Russia’s Institute of Biomedical Problems and the European Space Agency. The project is called Mars500.

They closed the hatch on the “Isolation Facility” on June 3, 2010 and will re-open it later this year, on November 5, 2011. In meantime the 6 crew will practice the entire daily schedule of all the many tasks needed to for a round trip landing on Mars. This includes suiting up for excursions on the martian surface.

Right on schedule the Mars500 virtually landed on “Mars” last month on February 1, 2011. They are now on their way back to Earth. You can see a video blog of their journey at the halfway point.

The entire “space ship” is about the size of a large apartment. While they are not growing their own food, they do have some green plants under grow lights, a kitchen, an exercise corner, and bunk beds. Watch this VR tour to get sense of how small the space is.

Part of the experiment is to study the psychological effects of what happens when six guys are cooped up in such a small space for a long journey.

Effects of group dynamics and loneliness on cognitive and emotional adaptation to extreme, confined environments: The aim of this study is to understand if long-term space flights lead to stronger feelings of stress, for instance loneliness, and whether this might have an effect on performing and controlling professional tasks.

They are testing the effects of vibration exercise, vitamin supplements and blue light.

Effect of blue-enhanced light on alertness and sleep- wake behaviour: Insufficient background lighting could induce detrimental physiological changes, affecting sleep, performance and metabolism. Using stimulation by blue-enriched light, an evaluation will be made of the cumulative effect of the visible light in the Mars500 isolation chamber on sleep-wake behaviour, sleep quality, subjective alertness levels, and circadian rhythms. The aim of the proposed project is to execute countermeasures to prevent muscle and bone loss and to stimulate the cardiovascular system by continuous training. The training programme is based on the Galileo 2000-plus vibration device which is applicable in weightlessness. During the 56-day Berlin Bed Rest Study in 2003, resistive vibration exercises were introduced for the first time, and proved to be the most effective countermeasures against loss of structure and function of muscle and bone related to immobility.

There’s a lot of background in this PDF. They have their own YouTube channel.