MOSCOW - Six men are emerging from three months of isolation in Soviet-era metal tubes after completing an experiment simulating a mission to Mars.

Four Russians, a German and a Frenchman were sealed in the mock spacecraft on Moscow's outskirts for 105 days, cut off for the most part from the outside world.

Crew captain Sergei Ryazansky told reporters Tuesday that the most difficult part of the experiment was that "it was not for real."

The six volunteers ate space rations and used toilets and other life-support facilities closely resembling those on a space station.

The joint Russian-European experiment was aimed at learning more about the psychological and physical stresses that travellers to Mars might face.