MOSCOW -- Russian engineers broke a red wax seal and six men emerged from a metal hatch after 105 days of isolation in a mock spacecraft, still smiling after testing the stresses that space travelers may face on the journey to Mars.
Sergei Ryazansky, the captain of the six-man crew, told reporters at a Moscow research institute near the Kremlin on Tuesday that the most difficult thing was knowing that instead of making the 172-million mile (276-million kilometer) journey they were locked in a windowless module of metal canisters the size of railway cars.
The men, chosen from 6,000 applicants, were paid euro15,000 ($20,987) each to be sealed up in the mock space capsule since March 31_ cut off almost entirely from the outside world.
They had no television or Internet and their only link to the outside world was communications with the experiment's controllers -- who also monitored them via TV cameras -- and an internal e-mail system. Communications with the outside world had 20-minute delays to imitate a real space flight.
Each crew member had his personal cabin. The interiors had hatches similar to a submarine's and were paneled in faux wood according to Soviet style of the 1970s, when the structure was originally built for space-related experiments.
The module's entrance was locked with a padlock and red sealing wax and twine -- the kind that Soviet government bureaucrats have used for years to close up their offices at the end of the work day.
Common facilities included a gym and a small garden, and the modules were equipped with the new European and Russian exercise and training equipment for biomedical research. The crew also specially prepared meals and used toilets closely resembling those on the space station.
Some veteran space explorers belittled the value of the experiment, but its backers at the Russian and European space agencies insist it will only move humans closer to a real mission.
"What we're doing is important for future missions exploring the solar system," said Simonetta Di Pipo, director of the human space flight program at the European Space Agency.
"The most difficult part was that the flight was not for real," Ryazansky, wearing a blue, NASA-style jumpsuit with a large patch reading "MARS 500," told reporters hours after he and the crew emerged from the modules.
Crew member Alexey Baranov complained that the worst thing was not being with his relatives: "The separation from my loved ones and nature was depressing."
Russian TV showed images of the men -- four Russians, a German and a Frenchman -- during their stay, conducting experiments, lifting weights or lounging in leather reclining chairs, surrounded by throw pillows and Oriental rugs.
The men said most of them gained weight during their stay, exercising much of the time, and running experiments for medical researchers.
Psychologist Olga Shevchenko said they avoided conflicts thanks to a busy schedule and intense physical training. However, she said they all complained being deprived of sights of the natural world and separation from their families.
While officials at the Institute for Medical and Biological Problems praised the experiment as a success and promised to conduct a 500-day simulation experiment later this year, some veterans of the Soviet or Russian space programs doubted its value.
"This is nothing but a test for a long isolation of average people," a two-time cosmonaut Valentin Lebedev wrote in an opinion column published in the Sovietskaya Rossiya newspaper daily last month. "Such an experiment has only vague relation to understanding the possibility of interplanetary flight."
The experiment was the second for the institute, whose previous effort in 1999 ended in scandal when a Canadian woman complained of being forcibly kissed by a Russian captain and said that two Russian crew members had a fist fight that left blood splattered on the walls.
Russian officials at the time downplayed the incidents, attributing it to cultural gaps and stress.
Soviet engineers also tried a similar yearlong experiment, but that was interrupted because of unending conflicts between crew members.