Monotony was 'most difficult part' of simulated Mars trip - http://www.newscientist.com/article...
"A group of volunteers that spent 105 days locked up in a mock spaceship simulating a trip to Mars is finishing up their final tests this week. The programme, which was used to test the psychological and physiological effects of isolation, will pave the way for a longer 520-day mission that will take place in the first half of 2010." - Michael McKean