Rock Breaking Techniques Using High Concentrated Energy Sources for Space Mining Applications

The technical feasibility of non-conventional rock breaking techniques for space mining applications was assessed using high concentrated energy sources. A continuous and pulsed ND:YAG lasers were used to melt, drill, and cut rock samples (basalt, anorthosite/granite, and breccia) using a wide range of laser parameters. When the laser energy was concentrated on a rock sample, the temperature of the rock increased, leading to the melting/vaporizing of the material. Melting of granular materials led to the formation of a glassy sheet. This solidified material, bonded by intragranular glass, is convenient for handling, transportation, and for further processing. Blocks of fused material are useful for manufacturing building materials or processing as ore to extract needed metals and gasses. The effect of different laser input energies on the microstructure and mechanical properties of the rock samples were evaluated. Preliminary results suggest that a nanosecond pulsed laser is capable of laser ablation sufficient to cut rock materials similar to those present on the lunar surface. The overall continuous laser interaction with the rock samples resulted in melting and re-solidification in localized areas. The microhardness of the melted regions resulted in significant increase compared with the unmelted regions. Both anorthosite and basalt materials resulted in glassy phase formation after solidification. However, breaking and fracturing was observed with the continuous laser interaction with the breccia rock material.