Skylab's Body Mass Measurement chair, the facility of the Body Mass Measurement experiment (M172), is shown here in this 1970 photograph. The M172 experiment determined the body mass of each crew member and observed changes in body masses during flight. Knowledge of exact body mass variations throughout the flight in significantly aided in the correlation of other medical data obtained during the flight. Mass measurements under zero-gravity conditions were achieved by the application of Newton's second law (force equals mass times acceleration). The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

S73-20622 (March 1973) --- Scientist-astronaut Joseph P. Kerwin, science pilot of the first manned Skylab mission, demonstrates the Body Mass Measurement Experiment (M172) during Skylab training at the Johnson Space Center. Dr. Kerwin is in the work and experiments area of the crew quarters of the Skylab Orbital Workshop (OWS) trainer at JSC. The M172 experiment will demonstrate body mass measurement in a null gravity environment, validate theoretical behavior of this method, and support those medical experiments for which body mass measurements are required. The data to be collected in support of M172 are: preflight calibration of the body mass measurement device and measurements of known masses up to 100 kilograms (220 pounds) three times during each Skylab mission. The device, a spring/flexure pivot-mounted chair, will also be used for daily determination of the crewmen?s weight, which will be manually logged and voice recorded for subsequent telemetered transmission. Photo credit: NASA