A crew of would-be astronauts from Europe, China, and Russia has emerged from a 520-day simulated space mission to a hero's welcome, even though the Mars500 team never left the Earth.

The 18 months spent in a spacecraft firmly planted on the ground was meant to mimic a real mission to Mars; 250 days to get there, 30 days in orbit and to land, and another 240 days to return.

Along with scientific experiments and maintenance work, the $15m exercise was meant to gauge the physical and mental strains of the prolonged space journey in space.

Al Jazeera's Imran Khan reports.