Abstract
optical and tracking systems were summarized, and the role of nonlinear effects was discussed. Two aspects of the situation have changed since the completion of that project. First, the risk of valuable-asset damage has increased and is now so serious that governments may be willing to spend money on orbital-debris removal. Second, a significant advance in powerful pulsed-laser technology has taken place, mainly at Lawrence Livermore National Laboratory, with the completion of the National Ignition Facility Project. 3 Systems designed for inertial-confinement-fusion applications are a near-perfect fit for orbital-debris-removal applications. We begin the analysis with the requirements for the laser pulse on the target. Then, we discuss beam propagation and focusing to more completely define the requirements for the laser. Based on these more specificrequirements,wespecifyarangeofparametersforlaseroperation. We demonstrate that the laser-pulse power substantially exceeds the critical power for self-focusing in air. However, because the laser light is propagated almost vertically, the self-focusing length is much longer than the thickness of the atmosphere. Our numerical calculationsdemonstratethatthespatialstructureofthebeamonthetargetis smooth, without filaments, but the nonlinear effects noticeably decrease the peak intensity. We demonstrate that the atmosphere can be treated as an additional focusing lens and that preliminary beam defocusing can significantly compensate for the detrimental effects of the atmosphere. The detrimental effects of nonlinearity can be greatly reduced if the laser is placed at a high elevation. This reduction is the result of the decreased air density and reduced the atmospheric thickness through which the beam propagates when the laser is at a high elevation. In the last section, we discuss the role of additional nonlinear effects, including the beam broadening caused by atmospheric turbulence. We demonstrate that these detrimental effects are important, but we argue that proper optimization of the laser and beam-control system renders the ground-based laser space-debris cleaning approach feasible.
Highlights
The proliferation of satellites in Earth orbit, which are increasing in both number and value, makes the problem of collisions with orbital debris very real
We demonstrate that the laser-pulse power substantially exceeds the critical power for self-focusing in air
We discuss the role of additional nonlinear effects, including the beam broadening caused by atmospheric turbulence. We demonstrate that these detrimental effects are important, but we argue that proper optimization of the laser and beam-control system renders the ground-based laser space-debris cleaning approach feasible
Summary
The proliferation of satellites in Earth orbit, which are increasing in both number and value, makes the problem of collisions with orbital debris very real. One of the most practical solutions to this problem is debris removal facilitated by a ground-based pulsed laser. In this approach, laser pulses ablate debris material, change the debris velocity and move the debris to a lower orbit, where natural burn-up occurs (Figure 1). Laser pulses ablate debris material, change the debris velocity and move the debris to a lower orbit, where natural burn-up occurs (Figure 1) This method of debris removal has been analyzed by the ‘Orion’ project;[1,2] in this analysis, requirements for the laser and optical and tracking systems were summarized, and the role of nonlinear effects was discussed. Systems designed for inertial-confinement-fusion applications are a near-perfect fit for orbital-debris-removal applications
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