PRINCIPAL INVESTIGATOR(S): Jerry L. Homick, and Earl F. Miller 



EXPERIMENT TITLE/NUMBER : Apollo Flight Crew Vestibular Assessment 



PROGRAM/MISSION : Apollo 



CLASSIFICATION : Human 



DISCIPLINE(S) : Neurosensory, Behavioral science 



OBJECTIVES : To observe the effects of space flight on the human vestibular 

 system. 



PROTOCOL : Motion sickness history files were compiled on each astronaut. No 

 systematic program to quantitatively assess the effects of space flight on 

 crew vestibular function was pursued prior to Apollo 16. For the last two 

 Apollo missions, postural equilibrium was tested by a modified standard lab 

 method with crewmen balancing on four rails of different widths plus the 

 floor. There was a tape for foot alignment on the floor. Time, the 

 performance measure of balance, began when the crewmen, while standing on the 

 prescribed support with his feet in a tandem heel-to-toe arrangement, folded 

 his arms. The test was made with eyes open, then closed. Nystagmus was 

 measured with the aid of recording electrodes placed around the eyes. Caloric 

 irrigation complemented tests of balance by monitoring change in semicircular 

 canal activity. Irrigating temperatures were 3^.0 degrees C and 35.5 degrees 

 C. Tests were taken for Apollo 16 on F-30, R+3, and R+7, and for Apollo 17 on 

 F-30 and F-15 and none postflight. 



EQUIPMENT : Electronystagmograph , postural equilibrium rails. 



RESULTS : Eleven of the 33 individuals who have flown on Apollo flights have 

 experienced apparent vestibular difficulties. Of these eleven, nine had 

 positive motion sickness histories. Conversely, 18 of 27 individuals with 

 positive histories had no inflight symptomatology. Six of the eleven crewmen 

 with inflight problems experienced minor symptoms, two experienced moderate 

 symptoms, and three had severe symptomatology. It is questionable whether the 

 vomiting experienced by one of these latter individuals was vestibular in 

 origin or due primarily to gastroenteritis. Six (40 percent) of the 15 

 individuals making their first space flight developed inflight symptoms. Of 

 the 18 veteran pilots, only five (approximately 28 percent) experienced 

 symptoms . 



For the Apollo 16 crew, during the first (R+3) and second (R+7) postflight 

 test periods, postural equilibrium with eyes open was nearly identical to 

 pref light performance for all crewmen. The CDR actually demonstrated a slight 

 progressive improvement on this task with time. At R+3> however, the CDR and 

 the CMP exhibited a marked decrease in postural stability when deprived of all 

 visual sensory cues. When these two individuals were tested again at R+7, 

 there was a definite improvement in postural stability with eyes closed 



37 



