Recent advances in laser ablation modelling for asteroid deflection methods

Abstract

Over the past few years, a series of studies have demonstrated the theoretical benefits of using laser ablation in order to mitigate the threat of a potential asteroid on a collision course with earth. Compared to other slow-push mitigation strategies, laser ablation allows for a significant reduction in fuel consumption since the ablated material is used as propellant. A precise modelling of the ablation process is however difficult due to the high variability in the physical parameters encountered among the different asteroids as well as the scarcity of experimental studies available in the literature. In this paper, we derive a new thermal model to simulate the efficiency of a laser-based deflector. The useful material properties are first derived from thermochemical tables and equilibrium thermodynamic considerations. These properties are then injected in a 3D axisymetrical thermal model developed in Matlab. A temperature-dependant conduction flux is imposed on the exterior boundary condition that takes into account the balance between the incident power and the power losses due to the vaporization process across the Knudsen layer and the radiations respectively. A non-linear solver is finally used and the solution integrated over the ablation front to reconstruct the net thrust and the global mass flow. Compared to an initial 1D model, this new approach shows the importance of the parietal radiation losses in the case of a CW laser. Despite the low energy conversion efficiency, this new model still demonstrates the theoretical benefit of using lasers over more conventional low-thrust strategies.

Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

“…Note that in the case volume absorption is considered, the temperature peak is located under the surface, as explained by Anisimov and Luk'yanchuk (2002). Thiry and Vasile (2014) reported that the correlated color temperature recorded from the light emitted by the ablation spot with a Nd:YAG laser was consistent with the temperature predicted by the model assuming surface absorption. In the remaining, we thus carry on with the assumption that the material is a surface absorber at the laser wavelength.…”

Experimental Investigation of Impulsive Coupling Characteristics of Asteroid Simulants Based on Laser Ablation Propulsion

“…Especially for ground-based laser systems, a short deflection time is almost invalid due to the duration of irradiation to the asteroid. Thiry et al presented a new 3D thermal model of the laser ablation applied to the deflection of an asteroid, in order to calculate the efficiency of a laser deflection system [17]. They calculated that the coupling efficiency of a high-energy laser can reach 80 N s / J μ ⋅ theoretically.…”