The amount of water ice contained within prepared samples of JSC-1 lunar regolith simulant strongly affects the excavatability of the material. As part of a NASA Phase I SBIR project, load-penetration testing of JSC-1 lunar regolith simulant was performed at water ice concentrations ranging from zero to 11% by mass (approximately saturated), after compaction and cooling to simulate probable lunar conditions. After mixing dry JSC-1 simulant with the appropriate amount of water, the samples were individually compressed into containment rings under 48 MPa of pressure. Thermocouples embedded in the samples monitored internal temperature while they were cooled in a bath of liquid nitrogen. At temperatures corresponding to the lunar polar cold traps, a 19mm-diameter hemispherical indenter was forced into the center of each sample while the required force and the resulting penetration were recorded. The results show strong sensitivity to water content. Regolith containing up to 0.3% water ice is very easy to excavate and behaves like weak coal. Regolith with 0.6 to 1.5% ice is readily excavatable and acts like weak shale or mudstone. Regolith with ~8.4% ice would be excavated with mechanical excavators, much like moderate-strength limestones, sandstones, and shales. The highest strength mix (~10.6% ice) behaves like strong limestone or sandstone, which require massive excavators. These results show that realistically compacted ice-regolith mixtures may be harder to excavate than previously believed, and that mixture variability must be well-understood to design effective excavators.
L. S. Gertsch et al., "Effect of Water Ice Content on Excavatability of Lunar Regolith," Proceedings of the 10th Conf. on Thermophysics Applic. in Micrograv.; 23rd Symp. on Space Nucl. Power and Propulsion; 4th Conf. on Human/Robotic Technol. and the Nat. Vision for Space Explor.; 4th Symp. on Space Coloniz.; 3rd Symp.on New Front. and Future C (2006, Albuquerque, NM), vol. 813, pp. 1093-1100, American Institute of Physics (AIP), Feb 2006.
The definitive version is available at http://dx.doi.org/10.1063/1.2169290
10th Conf. on Thermophysics Applic. in Micrograv.; 23rd Symp. on Space Nucl. Power and Propulsion; 4th Conf. on Human/Robotic Technol. and the Nat. Vision for Space Explor.; 4th Symp. on Space Coloniz.; 3rd Symp.on New Front. and Future C (2006: Feb. 12-16, Albuquerque, NM)
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Excavation; Fragmentation; Ice; Mining; Regolith
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Article - Conference proceedings
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