Analytic Model of Dynamic Response of Proposed Space Elevator to Anchor Point Repositioning
- Paper number
IAC-05-D4.3.04
- Author
Dr. Steven Patamia, Los Alamos National Laboratory, United States
- Coauthor
Dr. Anders M. Jorgensen, Los Alamos National Laboratory, United States
- Year
2005
- Abstract
We will discuss analytically derived dynamic behavior assoicated with moving the elevator's anchor point -- a maneuver expected to take place several times daily to avoid low Earth orbit debris. We apply elements of the general analytical model of the proposed space elevator we have been deriving to model large scale dynamics. The modeled design entails a ribbon, made using carbon nanotubes, which extends some 100,000 km from a movable anchor on the equator. The space end of this ribbon is terminated by a large counterweight and the fact that the counterweight has its own transverse degree of freedom mathematically complicates some phases of the repositioning process. The dominant response to repositioning is a pendulum motion, but the enormous length of the elevator entails a response lag of around 4 hours before the counterweight participates in the dynamics. There are nuanced variations in the pendular response during and after repositioning of the anchor. The mode which sets in after repositioning has a longer period than any pendular mode which becomes established during a sufficiently long anchor movement. These modes may be difficult to damp and repositioning again soon after a previous repositioning will complicate the resulting response further and make precise avoidance maneuvers difficult.
- Abstract document