Mars simulation: Men 'return' to Earth after 520 days
Six men locked away in steel tubes for a year-and-a-half to simulate a mission to Mars have emerged from isolation.
The Mars500 project, undertaken at a Moscow institute, was intended to find out how the human mind and body would cope on a long-duration spaceflight.
It is a venture that has fascinated all who have followed it around the globe.
The study even saw three of the men carry out a pretend landing on Mars, donning real spacesuits and walking across an enclosed sandy yard.
Daniel Sandford reports from Moscow.