OK, everyone squeeze in

Six-man crew to simulate long, cramped journey to Mars

MOSCOW - An international team of researchers in Russia on Thursday began a grueling simulation of a flight to Mars that will keep them locked in a cascade of windowless modules for 520 days - the amount of time required for a journey to the Red Planet and back to Earth.

While the experiment, conducted jointly by Russia, China and the European Space Agency, will not involve weightlessness, it will try to tackle some of the psychological challenges of a real flight to Mars - particularly the stress, claustrophobia and fatigue that a real space crew would face during interplanetary travel.