Prospecting for lunar volatiles using thermal methods

Abstract

Prospecting for water ice is a novel concept for terrestrial mineral exploration. On Earth, water and volatiles are typically available in liquid or gas. Although, as we reach out into the solar system, humans and spacecraft need water, methane, secondary alcohols, and acids. These enable human exploration, spacecraft fuel, and chemicals to process minerals. The solar system contains numerous cold bodies, such as lunar Permanently Shadowed Regions (PSR) where water and many of this volatiles are abundant. Unlike on Earth, these volatile minerals are solid. Prospecting for solid rock minerals is generally accomplished by drilling. An energy and time-intensive process. This body of work proposes a new prospecting method that leverages the unique properties of volatiles through the application of thermal energy.

A Thermal Probe is constructed with a thermally isolated tip. The probe is inserted into icy regolith and a relatively small amount of thermal energy is applied to the tip. As heat transfers into the icy regolith, the thermal energy decays as a function of wt\% and the ice structure. With sufficient heat applied, the thermal response is independent of the ice structure as long as pore space exists. By applying sufficient thermal energy to cause volatiles to sublimate, a transient atmosphere develops in the pore space of the regolith simulant. This temporarily allows heat transfer through convection as well as conductivity and radiation. The results of this paper show that wt% can be predicted within +-2%, regardless of the volatile structure type.