Crewmembers in the spacelab with the Lower Body Negative Pressure Study.

STS050-291-027 (25 June-9 July 1992) --- Astronaut Bonnie J. Dunbar uses a Doppler to collect medical data from Lawrence J. DeLucas, payload specialist, during his diagnostic "run" in the Lower Body Negative Pressure device (LBNP). The Doppler is used to pick up high-frequency sound waves from the surface of the heart, thus producing pictures on the monitor of the American Flight Echocardiograph (AFE). The result of the LBNP procedure is expected to be an increased tolerance of orthostatis - or standing upright - upon return to Earth's gravity. LBNP has been used a number of times in the United States space program, as early as the Skylab missions. STS-50 is the fourth flight of the current collapsible unit. Researchers are refining the LBNP protocol which will be used operationally on future 13 through 16 day missions.