Adaptation to head movements during short radius centrifugation

A fundamental lower limit to the radius of an artificial gravity centrifuge for long duration human space flights is the high rotation rate needed to achieve the acceleration needed at the rim. At high angular speeds, head movements out of the plane of rotation produce unexpected and disturbing Coriolis forces and cross-coupled angular accelerations, which lead to motion-sickness and disorientation. Previous studies in slowly rotating rooms set the practical upper speed limit at 6 rpm. Our research on intermittent repeated exposure to a short (2 m radius) high speed (23rpm,138∘/s) centrifuge has shown that most subjects can adapt to such head movements in a short time, and retain adaptation over days or weeks. The practical implications of this include the use of intermittent short radius centrifugation for long duration flights and the possibility of adapting astronauts to the unusual stimulus before flight. Theoretical issues include the possible development of a generalized internal model to describe the effects of Coriolis forces, as opposed to the development of families of stimulus–response relationships.