Artificial or variable gravity attained by tether systems

The simplest orbiting tethered system demands for stability that the mass centers of two end bodies be displaced above and below the position of zero acceleration. Therefore, the contents of the end bodies are subjected necessarily to acceleration fields or artificial gravity whose magnitudes depend on the dimensions and masses of the system. If the length of the tether changes, so do the fields. Even for a fixed tether length, the acceleration field at a location in the system may be somewhat variable unless special means are employed to maintain a constant value. These fundamental properties of a tethered system can be used to advantage if small or variable acceleration fields are desired for experimental or operational reasons. This potential use involves a few expressions from a formulation of tether system dynamics. Some of these formulae were collected for convenient use. Two and three body tethered equilibrium equations are explained. A special application of acceleration field control using a tether system is attainment of near-zero gravity. In this applicaition, even small variations about zero become a critical matter.