The Mars500 crew entered the isolation facility today in Russia. Six people will stay inside the simulated space-ship for 100 days. The European and Russian research project is looking into the social issues that arise when humans live together in a small space for an extended period of time.
A trip to Mars would take 500 days. The 100 days the guys spent in isolation is just a short trip actually.
During their stay in the facility, the crew will experience all aspects of a mission to Mars, including launch, the outward journey, arrival at Mars and, after an excursion to the surface, the long journey home.

Their tasks will be similar to those on a real space mission. They will have to cope with simulated emergencies, maybe even real emergencies. Communication delays of as much as 20 minutes each way will also be simulated.

The crewmembers will act as subjects in scientific projects 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 Mars500 team consists of 4 Russians cosmonauts Oleg Artemyez and Sergei Ryazansky, Alexei Baranov, a doctor, and Alexei Shpakov, a sports physiologist. Joining from the ESA are French Cyrille Fournier and German Oliver Knickel.

I wonder how much Vodka they have taken for the trip - calculating 100 days times 6 guys (4 of the Russians) equals at least 600 liters.
Via the ESA site.