Six men locked away in steel tubes for a year-and-a-half to imitate a mission to Mars are set to end the research. 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.
The crew has comprised a trio of Russians (Alexey Sitev, Alexandr Smoleevskiy and Sukhrob Kamolov), two Europeans (Romain Charles and Diego Urbina), and a Chinese national, Wang Yue.
Everything changes for the men when they "land" back on Earth at 14:00 Moscow time (10:00 GMT). That is when the hatch to their sealed home at the Institute of Biomedical Problems (IMBP) is opened for the first time since 3 June, 2010. It is expected the crew will have a few brief moments to wave to cameras and perhaps make a quick statement before being whisked into quarantine for three days of medical checks.
For much of the Mars500 project, the six have had only limited contact with the outside world. Their "spaceship" has no windows, and the protocols demanded their communications endure a similar time lag to that encountered by real messages as they travel the vast distance between Earth and Mars.