Lunar regolith that has been cemented together by ice has a compressive strength comparable to rocks such as sandstone and limestone. On the other hand, dry regolith is similar to partially consolidated soil that could be excavated by a shovel. Removing ice from regolith in the lunar vacuum requires a relatively small energy input. We propose to exploit this qualitative change in character to minimize the energy needed to excavate and process ice-bearing regolith through the use of a Heat-Assisted Cutter (HAC) and accompanying Sierra Lobo Ice-Carving Excavator for Regolith (SLICER).
Preliminary calculations indicate that the energy per mass of water produced using this method is lower than existing methods. In Phase I, we will perform a test series to measure the energy needed for a heat-assisted cutter to penetrate regolith simulant with a range of ice concentrations in a simulated lunar environment. While fairly extensive data exists on the mechanical properties of lunar regolith with ice content, there is no data on the energy required to excavate using a heat-assisted cutter.
The HAC could be used in conventional surface rovers or in a configuration similar to a tunnel boring machine, with the HAC and a positioning mechanism replacing the cutterhead. During Phase I, basic conceptual design of both of these configuration will be performed to inform testing and development in Phase II.
The target of the heat-assisted cutting technology is harvesting water ice from permanently shadowed regions on the Moon. A system including the technology is predicted to meet NASA requirements for water production rate while having a mass that is compatible with planned lunar landers. The technology is also applicable to excavation of ice on Mars.
Commercial organizations are a potential market for the technology or its products in the form of water for human consumption or as a rocket propellant. As the cislunar economy develops, harvesting water ice is certain to be an important capability.