Assessment of collision risk to electrodynamic tether used for de-orbiting

An electrodynamic tether has been recently proposed as an alternative solution to remove spent upper stages and satellites from low Earth orbit. The electrodynamic tether is also subjected to orbital debris and meteoroids collisions, however. In addition, the collision risk on such tethers would be more serious than that on spacecraft. The collision risk on tether is great due to the very large collision cross sectional area, and because of the small diameter, tether has high risk of severing by collisions of relatively small orbital debris and meteoroids. Risk of the orbital debris collisions on the tether was studied in Kyushu University (Japan) and ISTI/CNR (Italy). These two studies used different techniques to evaluate the collision risk. We evaluate the severing risk of tether and the survivability of tether during the de-orbiting from LEO by each technique.