Safety implications of unscheduled situations in the operation of tethered satellite systems from the international space station

Abstract

Space based experiments involving the use of tethers were examined with a view to identifying the implications of unscheduled events such as tether severance and interference between the tether and other hardware. It is the authors opinion that these type of events, which have important consequences for the operation of tethers in space, have received insufficient consideration in the extensive literature on the subject. In particular, the investigation of the interference event appears to be completely new. The examination focussed on tether experiments planned for the forthcoming International Space Station (ISS). Results were obtained through the use of a highspeed, non-linear, computer simulation model specifically designed for use with tethered satellite systems. Simulations showed that both severance and interference were possible during retrieval of the tether, particularly if ‘skip-rope’ motion is initiated. The motion following each of these incidents is predicted and shows that these unscheduled events are potentially very hazardous for the ISS. While the results of these simulations are not directly applicable to specific operations on the ISS, they fulfill the primary purpose of this paper which is the demonstration of this new technology.