Applicants should send their CVs to the European Space Agency (ESA) in Paris, which is organising the longest "bed experiment" in Europe to discover more about the low- gravity effects of long-distance space flight.
Being bed-bound for 90 days as an ESA guest may not be as pleasant as it sounds. Each volunteer will be forbidden from getting out and walking around or even sitting up in bed to read.
Their beds will be set at a jaunty angle of six degrees so that the volunteers will lie with their legs slightly higher than their heads, to mimic the weightlessness of space, which fills the head and chest with body fluids. Half of the men will be allowed to exercise in the prone position, the rest will do little more than lie back and think of Mars.
The experiment will provide important insights into the effects of low- gravity without the expense of going into space, Didier Schmitt, head of life sciences and applications at ESA, told a conference on space medicine at University College London yesterday.
The research is part of the international effort to learn more about what happens to the bones, muscles and other sinews of the body under low-gravity conditions, to prepare for a possible manned mission to Mars.
"The fact that they lie horizontally and are not moving is similar to the effects of microgravity," said Dr Didier. "For a start you lose bone very quickly." The lack of exercise also causes muscle-wastage, fluid build-up in the respiratory passages and cardiovascular problems with a weakened heart.
Previous bed experiments - the Russians hold the record with one lasting a year - resulted in people fainting from low blood pressure when they were finally allowed to get up.
Scientists want to devise new ways of exercising the body during the six-month trip to Mars so astronauts can perform tasks that would keep them alive on arrival.
"When astronauts return to Earth after a long period in space they have people around to look after them," Dr Didier said. "No one will be there [on Mars] when they arrive. Yet they'll have to work immediately. We are working on micro-gravity countermeasures."
ESA is considering only male applicants but there are tentative plans to test women "in a couple of years".