Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Tethers Unlimited, Inc.Tether Rendezvousseparation between the payload and PCV along the local vertical and orbital velocity directions.Comparing this graph with the same graph for the rendezvous without tether deployement shown indemonstrates that this deployment maneuver can extend the rendezvous windown by about 12 seconds;after 12 seconds the 1 km of tether runs out and the PCV is accelerated quickly away from the payload. Inthis simulation, the payload and PCV rendezvoused at T=0 with zero positional error, but a slightvelocity error. This error, along with the slight force on the PCV due to friction of the tether leaving thedeployer caused the PCV and payload to drift apart slightly during the 12 second window. The relativemotion of the payload and PCV is illustrated more clearly in Figure 6, which plots the relative separationat intervals of 0.1 seconds. Like Figure 2, this plot shows that the relative motion is primarily along thelocal vertical. The payload could, however, perform small thrusting adjustments to counter this drift andachieve docking. Figure 7 shows the relative velocity of the payload and PCV in the seconds before therendezvous.10ÆZPayload Capture VehicleReleases Tethered GrappleSeparation (m)50ÆX-5-5 012-Second AR&C WindowGrapple AcquiresPayload and PCVHalts Tether Deployment5 10 15 20Time (s)Figure 5. Separation between payload and tethered grapple, with deployment of 1 km of tether toextend rendezvous window to 12 seconds. (Z axis is local vertical axis)2015ÆZ (m)1050-10 0 10ÆX (m)Figure 6. Relative separation between grapple and payload with tether-deployment for rendezvouswindow extension. Plots are every 0.1 seconds, and there are many points concentrated near 0,0.5