Momentum predictability and heat accumulation in laser-based space debris removal

Abstract

Small space debris objects of even a few centimeters can cause severe damage to satellites. Powerful lasers are often proposed for pushing small debris by laser-ablative recoil toward an orbit where atmospheric burn-up yields their remediation. We analyze whether laser-ablative momentum generation is safe and reliable concerning predictability of momentum and accumulation of heat at the target. With hydrodynamic simulations on laser ablation of aluminum as the prevalent debris material, we study laser parameter dependencies of thermomechanical coupling. The results serve as configuration for raytracing-based Monte Carlo simulations on imparted momentum and heat of randomly shaped fragments within a Gaussian laser spot. Orbit modification and heating are analyzed exemplarily under repetitive laser irradiation. Short wavelengths are advantageous, yielding momentum coupling up to ∼40 mNs∕kJ, and thermal coupling can be minimized to 7% of the pulse energy using short-laser pulses. Random target orientation yields a momentum uncertainty of 86% and the thrust angle exhibits 40% scatter around 45 deg. Moreover, laser pointing errors at least redouble the uncertainty in momentum prediction. Due to heat accumulation of a few Kelvin per pulse, their number is restricted to allow for intermediate cooldown. Momentum scatter requires a sound collision analysis for conceivable trajectory modifications. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

LARAMOTIONS: a conceptual study on laser networks for near-term collision avoidance for space debris in the low Earth orbit

“…To consider the dependencies of laser-exerted force from incidence angle and surface properties for different target geometries, the DLR code Examination Program for Irregularly Shaped Debris Targets (Expedit) is used, which combines discretization of laser beam and target surface for parallelized momentum computation. The code had formerly been developed for calculation of laser-imparted momentum in laser ablation and is described in greater detail in [21]. An interaction module for photon pressure had been developed subsequently and is firstly employed in this study.…”

“…Finally, the debris fragment population has been generated by a statistical approach using an estimate of A cs from DISCOS data on A rcs and generating a statistical distribution of axis ratios X /Y and Y /Z in agreement with the fragment statistics from ground-based satellite crash tests [22]; cf. [21] for more details on this method. An overview on shapes and axis ratios for all 9101 OOR targets is given in Fig.…”

“…The major impact on laser-induced force, however, comes with the debris' size and orientation, since this affects the optical cross section and therefore the losses from target outshining. Hence, similar to our previous work shown in [21], we have carried out Monte Carlo studies for each one of the 9101 OOR objects in which laser-matter interaction has been simulated for different randomly chosen target orientations using a uniform distribution for the Eulerian orientation angles. With the deliberate computational constraint of using N S = 11 samples at least, but not exceeding N S = 1000, Monte Carlo sampling has been monitored in each simulation, using as a stop criterion for 11 < N S < 1000 that the accuracy σ CI = 1.96 • σ X / √ N S of the 95% confidence interval of the imparted force alongside the beam axis has to be less than 10% of the average value X of the coaxial force component (and likewise for the fraction of laser energy, which reaches the target's surface).…”

Extension of non-equilibrium modeling of metal ablation to the thermal effect inside the target material using a two temperature model

“…Several research has been dedicated to the study of the feasiblity of space debris removal using pulsed laser beams [1][2][3][4] and have all shown that the understanding of the processes governing the laser-target interaction as well as plasma formation and expansion is crucial for an effective debris removal.…”

“…Extension of non-equilibrium modeling of metal ablation to the thermal effects inside the target material using a two temperature model Amina Ait oumeziane (1) and Jean-Denis Parisse (2), (3) (1) Centre RAPSODEE UMR CNRS 5302, IMT mines Albi-Carmaux, France.…”