Mars capsule: I guess it's gonna be a long, long time Reuters

Its critics have suggested it amounts to little more than sitting inside a giant tin can in a Moscow hangar with no sun, no fresh water, no alcohol and (one assumes) no sex for 520 interminable days.

But as the six fearless volunteers this afternoon sealed themselves inside a simulated mission to Mars, grinning and waving goodbye to their families before "blast-off", scientists insisted they were embarking on an unprecedented experiment that was no laughing matter.

The crewmen – three are Russian, one French, one Chinese and one a Colombian-born Italian – won't emerge from their isolation until November 2011.

Their goal is to recreate a return journey to the red planet, spanning a year and a half, complete with simulated emergency situations and realistic psychological pressures.

It will, say scientists, provide invaluable data on how a crew would cope with the difficulties and inevitable tedium of long-duration space flight. "This isn't a joke. It will give a lot of useful information, not just about Mars but also for Earth," said Dr Christer Fuglesang, a Swedish astronaut with the human spaceflight directorate of the European Space Agency (ESA).

He rejected suggestions that the experiment, named Mars 500, was more Red Dwarf than red planet. "People are isolated in many places in the world," he said. "We have scientists in the south pole for a long time, or in submarines. Then there are all those in jail."

The astronauts would be free to leave the experiment at any point, Fuglesang said, adding that he was confident none of them would.

The crew will live and work in a chain of cramped metal capsules. The highlight of their voyage will be a simulated spacewalk on Mars, which will take place in a large sandpit. Today journalists toured the sandpit while wearing 3D glasses – the experience was similar to wandering inside a dark and disappointing Moscow nightclub.

Before bidding farewell to the world, the six men conceded their experience would be tough. This is especially true for Alexey Sitev, the crew's 38-year-old Russian commander, who was recently married. Asked what his bride Ekaterina thought of his spending the next 18 months away from her, he admitted: "It is difficult to answer this question." But, he said: "I am not the first traveller who has left his family for a long time to discover new frontiers. When they got back, they found their families waiting for them."

The fact that the crew is single-sex should prevent the dangerous sexual tensions that have affected previous mixed missions. In 1999, participants in a similar experiment were given vodka to celebrate New Year's Eve: two members then brawled when one tried to kiss a Canadian female astronaut.

Chinese crewman Wang Yue struck an exalted tone: "When people say this is a simulation, that it isn't a matter of life and death, I tell them it's much more. It's the future of mankind." He added he would attempt to learn Russian during his odyssey.

The experiment is taking place in a sprawling hangar at Moscow's Institute for Medical and Biological Problems, in a suburb of dingy tower blocks and poplar trees. The institute began studying the likely effects of a Mars mission in the early 1960s.

Since the Apollo flights of the late 60s and early 70s, there have been no manned space flights beyond Earth's orbit. But Fuglesang said he hoped that a real manned space flight to Mars, with international collaboration, could take place in the next two decades or so, though not before 2025.

Mars 500 is designed to recreate as closely as possible the conditions of a spacecraft hurtling through the solar system. A return flight to Mars – 34 million miles from Earth – would take between 18 months and three years.

The six crew will spend 250 days performing flight tasks and experiments along the way – with half of them spending 30 days "on the planet" and the others remaining "in orbit". Getting home will take a further 240 days.

The 550 sq metre complex that will be their home includes four windowless modules for sleeping, working, storage and for medical and psychological experiments. Each man has a tiny 6 sq metre room. TV is banned but the crew can send emails and communicate with "ground control" via an authentically Martian time delay of 20 minutes. They can also take books, DVDs and video games.

Italian member Diego Urbina said he would be reading the entire works of Gabriel Garcia Marquez and French flight engineer Romain Charles said he was bringing his guitar "to annoy the other guys".

Oliver Knickel, a German who took part in a 105-day experiment in the same complex last year, said tensions between crewmates were inevitable. During his mock flight, the crew almost came to blows over use of the treadmill in the module's tiny gym. Knickel, a German army officer, did not enjoy eating only space rations selected by others. "You don't realise what a privilege it is to choose your own food," he said.

The challenges: battle against bugs and boredom



Eighteen months in isolation will take its toll on the physical and mental health of the Mars 500 crew and is likely to test their ability to work as a team.

The six have a storeroom full of rations and will eat the same meals as astronauts on the International Space Station, but these supplies must last the whole stay. A small greenhouse in one of the modules will provide meagre helpings of fresh food including tomatoes, radishes and strawberries.

The facility is not an entirely "closed environment", meaning water and air are piped in and waste is removed rather than recycled. There are no windows though, so the crew will live under artificial lighting for the 520 days.

The lack of natural light is expected to trigger physiological changes affecting sleep, mood and metabolism. The capsule will be lit for periods with a bluish light to see whether it counteracts any problems the crew experience.

A gym with treadmills and weights is provided but European Space Agency scientists still expect to see the crew's physical health deteriorate through lack of activity. The men will be given amino acids and omega 3 dietary supplements to see if they help to maintain their mood and keep their performance sharp.

Wherever you have humans, bacteria follow, and the mock-up space capsule has plenty of nooks and crannies where they can breed. On previous simulated trips, pathogens have grown rapidly and at the expense of more benign bugs, posing a health danger. The crew will swab themselves and the capsule to identify which bugs are taking hold. The bugs in the crewmen's mouths and guts are expected to change too, so some will take food supplements laced with bacteria to boost the "good" bacteria in their bodies.

The greatest problem by far will be coping with the stress of being locked in a small space, with limited company, for such a long time – and only an internet connection to the outside world. Stress can weaken the immune system, disrupt sleep and hormones and make people irritable and even depressed. The crew will monitor each other for signs of psychological problems, but they will also be regularly assessed through online tests.

Ian Sample