French scientists have completed an experiment in which they studied 14 men who lay in bed for three months. The study was part of an ongoing programme, supported by the European Space Agency (Esa), which was intended to simulate the effects of weightlessness on the human body. Scientists want to discover the best regime of drugs and exercise to keep astronauts fit on long-distance spaceflight. This could be a lengthy tour on the International Space Station (ISS) or a mission to the planet Mars.