PRINCIPAL INVESTIGATOR(S ) : William E. Thornton, and John W. Ord 



EXPERIMENT TITLE/NUMBER : Physiological Mass Measurements in Skylab 



PROGRAM/MISSION : Skylab 2, 3, 4 



CLASSIFICATION : Human 



DISCIPLINE(S) : Musculoskeletal 



OBJECTIVES : To determine the cause and time course of weight loss by making 

 controlled daily intake/output mass measurements inflight. 



PROTOCOL : The Body Mass Measurement Device (BMMD), with a capacity of 100 

 kilograms, was used to make a basal body mass measurement on each crewman 

 every morning inflight. The Specimen Mass Measurement Device (SMMD), with a 

 range of 50-1000 grams, was used to measure the mass of food residue, feces, 

 and vomitus. These devices utilized the inertial property of mass rather than 

 gravitational force to determine mass. 



EQUIPMENT : Body Mass Measurement Device (BMMD), Specimen Mass Measurement 

 Device (SMMD). 



RESULTS : Two general patterns of body mass loss were apparent. There was a 

 continuous loss beginning pref light with an increase in rate of loss inflight. 

 A second is indicated by relative stability except for a small loss during the 

 first days of weightlessness with a reciprocal gain during the first few days 

 postf light. A surprisingly high metabolic loss was present in all crewmen 

 except one, and a small fluid loss (on the order of a liter), appeared to 

 occur during the initial few days of weightlessness followed by a reciprocal 

 change on return. This loss was small and self-limited, and appeared to be 

 the only obligatory loss, the other losses being primarily metabolic. 



CONCLUSIONS : This experiment demonstrated a new instrument for inflight space 

 operations and research. Previously unproven mechanisms of weight loss under 

 weightlessness were demonstrated. The human body properly fed can be 

 sustained through missions of long duration without significant obligatory 

 loss of mass. 



PUBLICATIONS : 526, 527, 528 



82 



