sentences:  It is therefore important that the mechanisms responsible for this problem are studied and the appropriate controls are implemented to ensure that astronauts, in particular, those that are immunocompromised, are not affected.The work of Cain (2007) and others have seen the need to understand the hazards and risks of working in a low gravity environment.The general effects on the body of space flight or reduced gravity for example, as may occur on the Moon or during the exploration of Mars include changed physical factors such as decreased weight, fluid pressure, convection and sedimentation.