An international crew of researchers just returned from a 520-day space mission to Mars -- and it wasn't even real. An all-male crew of three Russians, a Frenchman, an Italian-Colombian and a Chinese citizen emerged from the Moscow facility after spending nearly a year and a half in a dark, isolated space with limited communication with others and meals from cans. The purpose of the $15 million experiment was to determine what a mission to Mars would really be like and to better prepare astronauts for the stress of the real thing. The crew, pale but happy, said they were proud to take part in the simulation that could become reality as soon as the mid-2030s. Most were paid about $100,000 each.