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Neurovestibular Aspects of Short-Radius Artificial Gravity: Toward a Comprehensive Countermeasure

Principal Investigator:
Laurence R. Young, Sc.D.

Organization:
Massachusetts Institute of Technology

Artificial gravity, produced by centrifugal force on a rotating spacecraft or an on-board centrifuge, is a promising general countermeasure to the debilitating effects of weightlessness that include bone and muscle loss, cardiovascular deconditioning and balance disorders. Dr. Laurence R. Young and his collaborators at MIT, Brandeis, Mt. Sinai and Johnson Space Center as well as in Zurich and Mainz, are exploring intermittent short-radius centrifugation as a way to produce artificial gravity. This group is investigating the potentially disturbing side effects caused by head movements while spinning at 180 degrees/sec, which include motion sickness and interference with cognitive and motor function. Their goal is to develop efficient means of safely adapting astronauts to repeated transitions into and out-of artificial gravity without excessive motion sickness.

NASA Taskbook Entry

Technical Summary

Artificial gravity (AG), produced by centrifugal force on a rotating spacecraft or an onboard centrifuge, is a promising general countermeasure to the debilitating effects of weightlessness. However, high-speed rotation above 180 degrees per second is necessary to produce one g or more on a short-radius (1.5 - 3 meter) centrifuge. Any astronaut head movement not parallel to the plane of rotation can induce strong cross-coupled spatial disorientation, motion sickness, postural disturbance and non-stabilizing compensatory eye movements. This project addresses the issues of adaptation to Coriolis forces and cross-coupled accelerations in accordance with the artificial gravity aim of NSBRI's Neurovestibular Adaptation Team.

The goal is to develop efficient means of adapting astronauts safely to repeated transitions into and out of AG without excessive motion sickness. Another goal of this project is to understand the side-effects caused by cross-coupled stimulation that produce motion sickness and could interfere with cognitive and motor function. Basic understanding of the roles played by vestibular and other sensors in adaptation to unusual environments and the associated disorientation and motion sickness will contribute to astronaut comfort and safety inflight and after landing.

Fundamental studies of the process of sensorimotor adaptation and practical means of controlling motion sickness and sway during rotation are combined in our five Specific Aims:

  1. Acquisition, generalization and retention of adaptation (MIT);
  2. Cognitive influences on adaptation, and effects of AG on human performance (JSC and MIT);
  3. Spatial orientation as influenced by AG (MIT and Brandeis);
  4. Adaptation of postural sway during AG (Brandeis), and;
  5. Effectiveness of Baclofen in controlling motion sickness by shortening the vestibulo-ocular reflex time constant (MSSM).

Human rotators spinning about an Earth vertical axis provide the stimuli for each investigation: a rotating bed at MIT, an on-axis chair at Mt. Sinai, a three-meter radius rotating room at Brandeis, and a one-and-a-half meter centrifuge at JSC. Measurements are made of compensatory eye movements, dynamic visual acuity, reading comprehension, illusory body motions, subjective motion sickness and postural sway.

Earth Applications

Head movements in a moving or rotating environment such as boats, airplanes and automobiles often provoke symptoms of motion sickness or other discomfort. The ability to control susceptibility to motion sickness by controlling the central time constant of the vestibular system is a major advance and has broad application on Earth.

Understanding motor adaptation to Coriolis forces in an artificial gravity environment is relevant for understanding clinical deficits of complex whole body movement on Earth.

This project's funding ended in 2008