Psychological effects:

The main problems are likely to be psychological. What’s needed from the astronauts are extraordinary communication skills, nerves of steel and a sense of leadership. But it is notoriously difficult to be cooped up with the same few people, day in, day out, with no escape for three months. This ‘Big Brother’ effect can bring people to blows, as the reality TV show itself has shown.

Other possible negative effects include reduced mental capacity and depression.

Men and women who go on a flight have to be social animals Stella Tkatchova, scientist and author on manned space flights

However, a volunteer can easily leave the experiment at any time if it all gets too much (he can literally step right out into Moscow’s Institute of Medical and Biological Problems where the experiment is taking place) but the aim is to stay the duration. (There are two back-up volunteers standing by to fill any places left vacant.)

Physical effects:

There are not a lot of pluses in a space journey. As well as the infamous SMS (Space Motion Sickness), reminiscent of seasickness, the volunteers also face an increased risk of cancer from the cosmic radiation, heart problems and a degree of osteoporosis up to 15 times that felt by post-menopausal women. Any bacteria that finds its way into the sterile capsule will become nastier than usual, making it hard to fight off a bug. The benefits of being back on dry land at the end of the experiment will be delayed while astronauts shake off nausea, dizziness and the inability to stand.

But for any short astronauts wishing they were taller, the spinal cord does stretch an average of 6 cm.
 

Radiation effects:

The Mars 500 is designed to reproduce as closely as possible the effects of space – including the change in gravity, the speed of racing through space and the cosmic radiation that would penetrate the spacecraft. Scientists are searching for ways to protect a craft against radiation, including surrounding it by water, one of the best elements for the task.

experts on Mars Physical strength is reduced by 40 % during a flight to Mars Fathi Karouia, researcher for NASA at the University of Houston, USA and participant in a similar experiment

The ground team must stay in constant contact with the crew – hampered a little by a 40-minute delay in communication – to be able to warn them of sporadic blasts of radiation from the sun: these are deadly but are fortunately predictable.