Yesterday, Russian engineers cracked the wax seal on a metal hatch, and six men emerged from the simulated space capsule where they had spent the last 105 days in experiment designed to simulate the isolation of a manned trip to Mars.

The experiment is part of a larger project dubbed "Mars 500." The three months the men spent in isolation are a precursor to another simulation to take place in 2010, when another crew will submit themselves to 520 days in isolation, the projected time it would take for a return trip to Mars [ABC News].

The four Russians, one German, and one Frenchman were chosen from among 6,000 applicants, and were paid about $21,000 each for participating. Inside the mock capsule, they conducted experiments to test their physical and psychological reactions to the isolation, and performed many of the tasks that would keep Mars-bound astronauts busy.

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 [AP].

The six men seemed cheerful and none the worse for wear after their months of isolation, and reported that there were no serious conflicts among the crew, unlike some previous experiments. Said French volunteer Cyrille Fournier:

"We had an outstanding team spirit throughout the entire 105 days" [SPACE.com]

. But the men did say that they missed their families and occasionally felt ground down by the monotonous work routine.

Among some of their activities: The Mars500 volunteers conducted daily medical checks, exercised, prepared microwavable foods from each others' countries, played poker and collected their own urine for analysis. They also grew some of their own food, such as lettuce, radishes and cabbage, to supplement the astronaut-style pre-packaged meals [SPACE.com].

Some have criticized the project, noting that the test subjects knew that they could exit the capsule if things got hairy; the experiment also made no attempt to replicate some important physical factors that astronauts on a real trip to Mars would experience, like weightlessness and increased radiation exposure.

"This is nothing but a test for a long isolation of average people," a two-time cosmonaut Valentin Lebedev wrote in an opinion column.... "Such an experiment has only vague relation to understanding the possibility of interplanetary flight" [AP].

There are no firm plans for a manned trip to the Red Planet, but the European Space Agency and NASA have indicated that they may aim for such a mission in about 30 years. Related Content: 80beats: Six Volunteers, Living in a Tin Can, Will Simulate a Trip to Mars 80beats: Traveling to Mars? You’ll Need This Miniature Magnetic Force-Field DISCOVER: Russia's Dark Horse Plan to Get to Mars DISCOVER: For the Love of Mars explores the Mars Society’s frontier vision Image: ESA