Living in a box, living in an expensive box...
They are competing for two of the six places in Mars500 - a full-scale simulation of a short-stay Mars mission (a year and a half each way, a month on the surface - don't get me started on how wasteful that is...).
The Mars500 facility, which is located on the IBMP site in Moscow, comprises four sealed modules. The total interior volume is about 550 cubic metres. There are no windows.
The walls in the living quarters have been covered with a wooden panelling to make them feel slightly less austere.
Looking after the participants' needs will be a mission control-room sited just outside the containers.
But the experiment's designers are determined to make the training exercise as realistic as possible, so they will introduce a time delay in communications after two months.
Because it can take about 20 minutes for a message to travel from Mars to Earth, it will take this amount of time in the simulation also.
The crew and their ground controllers will send text messages to each other and then have to wait for the replies.
It means there can be no real-time conversations with friends and family - and, in moments of crisis, it will mean the crew will have to make crucial decisions themselves.
I think the biggest test will be the social side - how will six humans, no matter how well-selected, deal with having nobody but each other for years on end, and being in each others' faces twenty-four hours a day?
Could we end up looking at the first murder in space?
Institute for Biomedical Problems