Implementing artificial gravity in certain areas of spacecrafts would solve many medical problems that arise from weightlessness, such as bone loss, muscle loss and balance problems. Dr. Laurence R. Young and his collaborators are exploring the feasibility of intermittent short-radius centrifugation (SRC) as a way to produce artificial gravity. Although SRC achieves artificial gravity, it causes side effects, such as inappropriate eye movements, motion sickness and illusory body tilts. The project seeks to overcome these side effects by investigating them and by finding ways to train subjects how to best adapt to the rotating environment.
Overview
Neurovestibular Aspects of Artificial Gravity Created by Short-Radius Centrifugation
Principal Investigator:
Laurence R. Young, Sc.D.
Organization:
Massachusetts Institute of Technology
Harvard-MIT Division of Health Sciences and Technology
Technical Summary
Artificial gravity (AG), produced by centrifugal force on a rotating spacecraft or an on-board 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 Earths gravity or greater on a short radius (1.5-3m) centrifuge. Any astronaut head movement not parallel to the plane of rotation can induce strong cross-coupled stimulation resulting in 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 AG aim of the NSBRI Sensorimotor 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 in flight and after landing.
Fundamental studies of the process of sensorimotor adaptation and practical means of controlling motions sickness and sway during rotation are combined in our specific aims. In the final year of this project, we focused on the theme: Acquisition, Generalization and Retention of Adaptation. We have been able to demonstrate that, with sufficient training, most subjects can tolerate head movements while rotating at speeds up to 30 rpm. The adaptation process is achievable by incremental adjustment of either centrifuge speed, head-turn angle or head-turn speed. Furthermore, we demonstrate the effectiveness of sleep in consolidating the adaptation.
In addition to the adaptation studies, we explored the effects of exercise while on the centrifuge. Finally, we introduced a potentially valuable clinical method for increasing peripheral circulation in the feet during AG. We intend to continue investigation of this clinical application following termination of the current project. We also intend to explore the effect of gravity gradients in AG on the cardiovascular system through multi-segment dynamic models and experiments.
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 AG environment is relevant for understanding clinical deficits of whole body movement on Earth because normal body movements generate large inter-segmental Coriolis forces.
Our preliminary results showing an increase in ankle level arterial pressure give promise for the utilization of AG or other related techniques to increase peripheral circulation to the feet and to help relieve the symptoms felt by diabetics and other patients.
Understanding motor adaptation to Coriolis forces in an AG environment is relevant for understanding clinical deficits of whole body movement on Earth because normal body movements generate large inter-segmental Coriolis forces.
Our preliminary results showing an increase in ankle level arterial pressure give promise for the utilization of AG or other related techniques to increase peripheral circulation to the feet and to help relieve the symptoms felt by diabetics and other patients.
This project's funding ended in 2004