The effects of space travel on the nervous system.

The translation of man from terrestrial to an extra terrestrial environment is accompanied by an upset in the servo-control of movement engendered by the removal of the normal gravitational signal. Unfortunately the "natural" response of the nervous system, to ocular and vestibular confusion, is to cause varying degrees of sickness which can only be avoided by choice of suitable space travellers i.e., those who are least upset by gravitational chaos. This will remain so until much more is learned about the fundamental physiological mechanisms whereby man maintains a correct head/trunk, head/eye, trunk/limb and eye/limb positional coordination and why if these are upset man's natural response is to vomit.