Impact risk assessment of deorbiting strategies in low earth orbits

Various strategies are currently investigated for deorbiting satellites at the end of life to comply with the 25-year rule adopted by several space agencies. A suitable indicator of the “damage risk” due to a collision with other orbiting objects should consider not only the impact cross section of the bare spacecraft but also the additional cross section of the deorbiting device and should make a distinction between low and high energy-density impacts, respectively, with soft and hard parts of the deorbiting device. This paper presents advancements made in the last few years in electrodynamic tether technology finalized at revising the soft-impact damage risk presented by these deorbiting devices to other objects in Low-Earth Orbit (LEO) when updated deorbit performance analysis and state-of-the-art design parameters are adopted. It is found that, thanks to their collision avoidance capability and the novel tape-like geometry, bare electrodynamic tethers, besides being very competitive at reducing the hard-impact risks, are reliable devices in reducing soft-impact risks.