Satellite Placement Using a Partial Space Elevator.

摘要

The space elevator has been proposed as an alternate method for launching cargo into space. However, the construction of such a structure requires a material much stronger than any currently in existence. Instead, a partial elevator is considered for satellite placement. In the first part of the thesis, the fundamentals of very long tethered systems are studied. From static analysis on a simple two-body system, it is demonstrated that an assumption made in the conventional analysis does not apply to very long tethered systems. For a uniform tether, the axial stress distribution is obtained. Following the Lagrangian approach, the equations of motion governing the planar librations of a multi-body tethered system are derived. From a linearization of these equations, the libration frequencies are found. Then, by solving the nonlinear equations numerically, the responses to various changes in the system parameters are determined. In the second part of the thesis, the use of a partial elevator in satellite placement is studied. In the case of single climber transit, residual librations occur, which alter the shape and size of the orbit of a satellite launched from the climber. An approach using two climbers is investigated in order to decrease the residual libration and thereby reduce orbit placement errors. Also, some energy calculations are done to determine whether the partial elevator offers significant advantages.