Phase-Plane Study of Spin-Up Dynamics of a Tethered Satellite System

摘要

The Human Exploration and Development of Space will involve prolonged exposure in humans to a mi-crogravity environment; this can lead to significant loss of bone and muscle mass, particularly for missions requiring travel times of several months or more, such as on a trip to Mars. One possible remedy for this situation is to use a spent booster as a "counter-weight" and tether it to the crew cabin for the purpose of spinning up the counter-weight/cabin system about its common center of mass like a dumbbell, hence generating artificial gravity for the crew during long duration missions. However, much needs to be learned about the dynamics and stability of such tethered systems before they can become flight possibilities. The investigation of spin-up dynamics, along with other aspects of tethered systems, is the focus of the Tethered Artificial Gravity Satellite (TAGS) project, a 2-part program to study the operation and dynamics of an artificial-gravity-generating tethered satellite system. A simple experiment to study spin-up dynamics of a tethered system can be done by deploying such a system in LEO, and then reeling in a portion of the tether, allowing Coriolis forces to spin-up the system. Phase-plane analysis of this procedure shows that the spin-up dynamics are very sensitive to the tether reel-in rate and the initial angular position of the tether axis relative to the local vertical prior to starting to reel in the tether; representative results of this anaylysis are presented in this paper.