Laser-induced spallation of minerals common on asteroids

The ability to deflect dangerous small bodies in the Solar System or redirect profitable ones is a necessary and worthwhile challenge. One well-studied method to accomplish this is laser ablation, where solid surface material sublimates, and the escaping gas creates a momentum exchange. Alternatively, laser-induced spallation and sputtering could be a more efficient means of deflection, yet little research has studied these processes in detail. We used a 15-kW Ytterbium fiber laser on samples of olivine, pyroxene, and serpentine (minerals commonly found on asteroids) to induce spallation. We observed the process with a high-speed camera and illumination laser, and used X-ray micro-tomography to measure the size of the holes produced by the laser to determine material removal efficiency. We found that pyroxene will spallate at power densities between 1.5 and 6.0 kW cm(-2), serpentine will also spallate at 13.7 kW cm(-2), but olivine does not spallate at 1.5 kW cm(-2) and higher power densities melt the sample. Laser-induced spallation of pyroxene and serpentine can be two- to three-times more energy efficient (volume removed per unit of absorbed energy) than laser-induced spattering, and over 40x more efficient than laser ablation.

Automated summary

The researchers conducted experiments on olivine, pyroxene, and serpentine using different power densities of laser for spallation, finding that pyroxene and serpentine could be spalled at certain power levels while olivine would melt at higher power levels. Laser-induced spallation of pyroxene and serpentine is found to be more energy-efficient and effective compared to laser-induced splattering.