A highly anticipated 520-day simulation of a manned mission to Mars is now underway in a virtual spacecraft that is located in Moscow.

As part of the monitored test, all six participants will not be able to leave the controlled environment until the project ends in November 2011.  The first 250 days will focus on a mock flight to Mars, with a 30-day scheduled "exploration" of the Martian surface, and a 230-day return trip.

There are three Russians, one French citizen, one Italian-Colombian, and one Chinese citizen currently living in the Mars500 isolation facility.  The crew will have two days off each week, but must remain inside of the capsule during the entire mock mission.

"Certainly, the crew is largely on its own here, with very limited communications with the outside world," said Martin Zell, ESA Director of Human Spaceflight, in an interview with the AP.  "They have to cope internally with a lot of conditions and to organize themselves."

The six-man crew will be able to communicate with their friends and family using the internet -- which will be interrupted to help mimic in-space communications -- and can only consume canned and freeze dried supplies like on the International Space Station (ISS).

Some critics have said that this mission isn't realistic, but the organizers of the mission, led by the European, Russian and Chinese space programs, said it will give the countries a better insight into how certain technologies will work in space.

As the ISS mission winds down, space nations already have their sights set on manned missions to Mars.  It's likely the moon will be used as a stepping stone to the Red Planet, as it'll still be decades before a country is expected to launch a crew to Mars.