Astronauts Jan Davis (left) and Mae Jemison preparing the Lower Body Negative Pressure (LBNP) apparatus during Shuttle Mission STS-47. The LBNP was carried in the Spacelab-J science module in Endeavour's cargo bay. During weightless conditions in orbit, blood and other body fluids are distributed evenly through the body, rather than being more concentrated in the legs as on Earth. To prevent any associated physiological effects, the LBNP reduces air pressure on the lower torso and legs to encourage a near Earth- like fluid distribution. STS-47 flew from 12 to 20 September 1992.