compared to their R+3 performance. The CMP improved his pref light, 

 eyes-closed scores, whereas the performance of the CDR was approximately 

 midway between his two previous scores. The caloric irrigation test revealed 

 increased nystagmus activity on R+3 in the CDR and to a lesser extent in the 

 CMP. Responses on both tests were near baseline values by R+7. 



CONCLUSIONS : Increased mobility and thus increased head movements as afforded 

 by the larger volume of the Apollo CM/LM, resulted in a higher incidence of 

 vestibular disturbances in the Apollo Program than in previous programs. In 

 most cases in which symptoms did occur, they were mild to moderate and could 

 be controlled by limiting head movements the first few days in flight. 

 Adaptation of the vestibular receptors to the weightless environment 

 apparently occurred within the first several days of flight for most 

 individuals. Extravehicular activity in one-sixth-g on the lunar surface 

 resulted in no disorientation or vestibular disturbances. Apparently, 

 one-sixth-g is an adequate stimulus for the otolith organs to provide sensory 

 information regarding gravitational upright and, hence, maintenance of 

 posture. With an important exception of the Apollo 15 mission, no crewmen 

 experienced pronounced vestibular disturbances after returning from space 

 flight. This finding suggests that adaptive processes that occur during 

 weightless space flight missions of up to two weeks in duration do not render 

 the vestibular system significantly hyposensitive or hypersensitive following 

 sudden return to a one-g environment. Vestibular problems cannot be predicted 

 reliably from previous history of motion sickness. However, astronauts making 

 their first space flight appear to be slightly more susceptible to the 

 development of inflight symptoms than are experienced astronauts. 



PUBLICATIONS : 27b 



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