Direct Force Measurement of Pulsed Laser Ablation of Asteroid Simulants

Subnanosecond laser ablation of asteroid simulants has been studied, and direct force measurements were made. A 0.7 ns pulsed laser was used, with a 40 kHz pulse repetition frequency, 1064 nm wavelength, and 33 W average power. High-fidelity simulants for carbonaceous chondrite meteorites of types CM, CR, and CI, as well as pyroxene rock and 6061 aluminum were ablated. The force response over 500 ms of ablation was measured using a load cell. In addition, the samples were weighed before and after ablation to determine the mass removal rate. Based on these measurements, the momentum coupling coefficient, specific impulse, and ablation efficiency were calculated. The asteroid analog materials were found to have a modestly higher momentum coupling coefficient than aluminum, although the specific impulse and efficiency were much lower. For asteroid mitigation missions, the asteroid itself is used as the propellant, and so a low specific impulse poses no problem.