This paper gives a general description of a full 520-day Mars mission simulation (Mars-500) with an international crew of three Russians, one Chinese and two Europeans (French and Italian) from the European Space Agency (ESA) and implemented in a space simulation facility at the Institute for Biomedical Problems (IBMP) in Moscow between 3 June 2010 and 4 November 2011. It provides an overview of the constraints potentially impacting psychological crew health in future interplanetary missions in general and the Mars-500 mission in particular. It describes the psychological support programme implemented during the Mars-500 mission and it shows some of the results in terms of efficiency of the psychological countermeasures. It focuses on the role and importance of crew communication and shows the results of a preliminary analysis of crew information support and private crew communication with the “outside world” which provides some initial basic indication in terms of crew information support and private crew communication requirements for future human exploration missions.