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

An electrodynamic tether system has been recently proposed as an alternative solution to remove spent upper stages and satellites from low Earth orbit. However, due to their peculiar structure and geometry, space tethers introduce unusual problems when viewed from the orbital debris perspective. In particular, tethers of normal design may have a high probability of being severed by impacts with relatively small meteoroids and orbital debris. The risk of impact of meteoroids and orbital debris with a space tether has been investigated at the Kyushu University (Japan) and at ISTI/CNR (Italy). The survival probability of a specific electrodynamic tether system during its baseline mission for end-of-life de-orbiting of spacecraft from different altitudes and inclinations has been assessed using different techniques to evaluate the collision risk. The Japanese and Italian results have been compared both for a single and a double line tether design.