Resisting lying down for ten days in exchange for a fee of five thousand euros : this is not the challenge of a reality show but a real scientific experiment that these days sees the participation of 20 volunteers recruited by the Medes Institute of Space Medicine in Toulouse (France) for the Vivaldi III clinical study, promoted by the French National Centre for Space Studies and the European Space Agency.

The participants (all men between 20 and 40 years old, in perfect health and non-smokers) will be randomly divided into two groups that will experience two different ways of simulating weightlessness .

Ten volunteers will lie down for ten days on an anti-orthostatic bed, that is, inclined six degrees so that the head is lower than the feet. The other ten volunteers will instead experience dry immersion : they will enter containers similar to bathtubs filled with water and remain immersed up to the torso, always protected by a waterproof fabric to avoid getting wet, in order to experience a sensation of floating similar to that experienced by astronauts on the International Space Station .

To never interrupt the simulation, meals will be served on a floating table and can be consumed using a pillow to support the neck . No breaks even to go to the bathroom : in case of need, participants will be temporarily transferred on a trolley, always maintaining their relaxed position.

The study involves participants remaining hospitalised for 21 days (including 10 days of dry immersion or rest on an anti-orthostatic bed) under the supervision of experts from Medes and ESA , who will conduct medical-scientific examinations and tests to evaluate all the physiological changes affecting the nervous system, vision, cardiovascular system and metabolism, as well as hormonal and immune changes.

The research findings will have implications not only for human space exploration, but also for medicine on Earth: they could , the elderly, and those suffering from musculoskeletal problems.