Heat Accumulation in Laser-Based Removal of Space Debris

Abstract

We highlight a side-effect of laser ablation which has almost been neglected so far in laser-based removal of space debris but causes significant restrictions to the removal process: The accumulation of residual heat in the target stemming from the laser ablation process might cause the debris target to become entirely liquid within less than a minute of repetitive laser irradiation. This might severely enhance the related hazard of the corresponding particle instead of reducing it. In order to allow for a rough assessment of the related set of problems, we introduce a so-called thermomechanical coupling coefficient. The general limitation of velocity change, given by the thermo-mechanical coupling coefficient, appears to be a general, physical barrier for laser-induced orbit modification without target cooling. The operational limit of the maximum acceptable number of pulses depends specifically on the mass, material, and temperature of the debris target. Therefore, remote analysis of debris material and temperature would be highly desirable for efficiently tailored laser debris irradiation keeping safety margins to prevent debris melting.