Attitude Stabilization of an Uncooperative Spacecraft in an Orbital Environment using Visco-Elastic Tethers

Active removal of large de-commissioned satellites is critical to the continued use of many of Earth’s orbits, as predicted by Donald J. Kessler in 1978. One solution to this problem is to use a tethered spacecraft system to capture and tow the highest risk debris to a disposal orbit. A signicant technical challenge lies with the capture, and subsequent stabilization, of a large and possibly tumbling debris. This paper addresses the target attitude stabilization aspect of the capture process. The two systems analyzed consist of 1) the currently accepted tethered spacecraft system where a single tether joins the target and the active chaser spacecraft, and 2) a newly proposed tethered spacecraft conguration that consists of a single tether attached to the active chaser spacecraft, which branches into four sub-tethers attached to the debris. An orbital environment is simulated, including gravity gradient torques. Incorporating the thrust ability of the chaser and exploiting the visco-elastic properties of the tethers, it is shown through numerical simulations that the proposed novel tethered spacecraft conguration provides an improved means of controlling the attitude of an uncooperative debris.