A real mission to Mars would take about 520 days—including the months it takes to travel there and back and the time spent on the Red Planet. But the longest any human has spent off Earth is 437 days straight, a record set in 1995 by Russian cosmonaut Valeri Polyakov, who was orbiting relatively close to home in the space station Mir. Polyakovseemed to bear the burden of long space flight fairly well, but many questions remain about just what a long mission farther from the sun would do to astronauts' ability to sleep and keep energized.
The $10m (£6.2m) Mars500 project, run by the European Space Agency (ESA) and the Russian Institute for Biomedical Problems, launched, metaphorically, when the hatch to the mock-up spaceship closed behind three Russians, two Europeans and a Chinese man in June 2010. The men spent the next 520 days in windowless isolation. Their only contact with the outside world was over the internet and by phone lines that carried a delay of up to 20 minutes, to mimic the time it takes radio waves to reach Mars from Earth.
Throughout the mission, the men endured daily medical, physical and psychological examinations, to help space agencies learn how humans cope with the stress, confinement and limited company that astronauts will face on future voyages. The crew fought boredom by watching DVDs, reading books and playing Guitar Hero on a games console. Mission controllers faked a fire and a power outage to keep them alert.
The ESA selected the crew from thousands of highly qualified applicants, and put them through a year of intensive training. But despite embodying "the right stuff" that underpins the astronaut corps, the men struggled with the tedium of the mission.
"The monotony of going to Mars and coming back again is something that will need to be addressed in the future. You don't want your crew hanging around doing nothing," Basner said.