Six volunteers will embark on an unprecedented simulation intended to mimic the timescale of a Mars mission.
An international team of volunteers is beginning a simulation of a manned mission to Mars.
Although the mission can replicate some aspects of a real journey, the so-called "scare factor" cannot be simulated.
The crew, controversially, contains no females.
Six men from Europe, Russia and China were Thursday locked away from the outside world for the next one-and-a-half years, in an unprecedented simulation of a manned mission to Mars.
One Chinese man, one Frenchman, one Italian and three Russians will spend the next 520 days in a 550-cubic-meter (19,400-cubic-foot) mock spaceship at a Moscow research institute to test how they cope with 18 months of isolation.
Dressed in blue overalls, the six gave the thumbs-up sign and grinned before the camera flashes as loved ones gave them an emotional send-off, some jokingly wishing them happy New Year already for 2011.
"See you in 520 days!" shouted Russian participant Sukhrob Kamolov, just before a scientist sealed shut the heavy iron door of the facility at around 1000 GMT.