THE PURPOSE OF THE PROPOSED WORK IS TO OBJECTIVELY CHARACTERIZE THE CHANGES IN FLUID DISTRIBUTION INCLUDING INTRA/EXTRACELLULAR AND INTRA/EXTRAVASCULAR FLUID SHIFTS BY APPLYING ADVANCED NONINVASIVE ASSESSMENT TECHNOLOGIES BEFORE DURING AND AFTER LONG DURATION SPACE FLIGHT.ADDITIONALLY WE WILL EXAMINE THE RELATIONSHIP BETWEEN THE TYPE AND MAGNITUDE OF THE FLUID SHIFT WITH ANY EFFECTS ON EYE MORPHOLOGY AND VISION DISTURBANCES INTRAOCULAR PRESSURE (IOP) AND MEASURES OF INTRACRANIAL PRESSURE. FURTHER WE SEEK TO DETERMINE WHETHER THE MAGNITUDE OF FLUIDSHIFTS DURING SPACE FLIGHT AS WELL AS THE ABOVE EFFECTS OF THOSE SHIFTS CAN BE PREDICTED BASED UPON CREWMEMBER BASELINE DATA AND RESPONSES TO ACUTE HEAD-DOWN TILT TESTS PERFORMED BEFORE LAUNCH. FINALLY WE PROPOSE TO EVALUATE THE EFFECT OF LOWER BODY NEGATIVE PRESSURE (LBNP) ON THE ABOVE PARAMETERS.