Control of a tethered artificial gravity spacecraft.

摘要

Human endurance in space is currently limited by physiological changes due to weightlessness that can be debilitating and dangerous upon reentry into an environment with gravity. The only countermeasure currently known that can completely prevent this physiological deconditioning is the elimination of weightlessness itself via artificial gravity.;It is possible to produce an Earth-like artificial gravity environment in a habitat module simply by connecting it to a counterweight with a long tether and slowly rotating the entire configuration. This results in a level of artificial gravity sufficient to eliminate all physiological deconditioning without exposing the inhabitants to rotation rates sufficient to induce motion sickness.;This research focuses on the dynamics and control of such a tethered artificial gravity spacecraft, particularly during the spinup maneuver to achieve the desired configuration rotation rate.;A laboratory model has been used to investigate the dynamics of such a system in two dimensions. The hardware model consists of two free-floating modules supported on gas bearings and connected to one another with a lightweight tether. Each module is equipped with sensors, an onboard computer and cold gas thrusters for spinup and module attitude control. Experiments have demonstrated the natural motions of this system during spinup and the use of reaction jets to provide active module attitude control for improved performance.;Results from the laboratory have been used to validate a computer simulation for predicting the three-dimensional motions of a full size tethered artificial gravity spacecraft. Simulation results show that very massive tethers can produce disturbance torques that significantly alter the module attitude dynamics. The tether lateral oscillations caused by the spinup maneuver and the resultant disturbance torques on the modules can be decreased by substantially increasing the time taken to spin up the configuration to the desired rotation rate. Even for a very massive tether, it is possible to spin up slowly enough so that regulation of the module attitudes to within 2 degrees of their equilibrium orientation for all times during and subsequent to spinup can be achieved by limited use of reaction jets to provide control torques during the spinup period alone.