Design of space elevator

A space elevator is a tall structure that starts from the surface of the Earth and reaches out beyond geostationary orbit (GEO) in space. The space elevator could be used to deliver payloads to any Earth’s orbit or send them to any other planet in the solar system. Currently, rocket propulsion is the only system that can deliver payloads to various destinations in space. The space elevator can provide easier, safer, faster and cheaper access to space compared to rocket propulsion system.

To date, most of the designs have been based on the simple linear decoupled dynamic analysis of the space elevator. These simple linear models neglect the Coriolis acceleration, elongation, and the coupling between the longitudinal and transverse motions. The simple models are useful for calculating the natural frequencies of the elevator, but they cannot give the accurate dynamic response. A three dimensional nonlinearly coupled model that includes the Coriolis acceleration, elongation, and the coupling between the longitudinal and transverse motions is used to accurately model the dynamic response of the elevator.

It is found that the linear models significantly underestimate the response of the system. Therefore, a non-linearly coupled model must be used to accurately predict the dynamic response of the system. However, the frequency contents obtained from the linear models are similar to those identified from the nonlinearly coupled models. Therefore, the linear models can be used to predict the natural frequency of the system for preliminary designs.

Two design cases have been proposed in this thesis. These designs satisfy various design criteria such as acceptable taper ratio, point mass, maximum tensile strength, maximum displacements. The design also takes care that the natural periods are sufficiently away from the tidal periods due to the Moon and the Sun. The first design case of the space elevator having a length of 66,000 km will be useful for reaching destinations within the Earth’s orbit and the second design case having a length of 91,000 km can also reach the destinations in solar orbit.