Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Tethers Unlimited, Inc.Tether RendezvousLoad Level10.80.60.4Without DeploymentWith Deploymentto Damp Tension Wave0.200 20 40Time (s)60 80 100Figure 15. Comparison of load level at tether tip in rendezvous maneuvers with and without additionaldeployment to damp tension waves.1Load Level0.80.60.4Capture after 5 sec.Deployment Braked over 10 sec.Additional Deployment atcontrolled tension from 25s-35sTether TipMiddle of TetherFacility0.200 20 40Time (s)60 80 100Figure 16. Tether load level during rendezvous maneuver in which the PCV deploys the tether for 5seconds to facilitate rendezvous, then captures the payload and slows the deployment over a period of 10seconds, and then later allows the tether to deploy under controlled tension to dampen the tether tensionwave. (Compare with Figure 13)Tension Behavior Due to Payload ReleaseWhen a rotating tether releases a payload, the sudden change in loading also causes tension waves totravel up and down the tether. These longitudinal oscillations, however, reduce the tether loading, sothey do not cause the tension to exceed the desired limits. Figure 17 shows the tether loading at tip,middle, and facility end of the tether after a payload release. The tip loading immediately drops to lowlevels, but the tension levels at the facility end and the middle oscillate. These oscillations eventuallydamp out due to frictional forces in the tether structure. The oscillations could also be dampened morequickly through controlled reeling and deployment of the tether.11