In situ dielectric spectroscopy for water detection on the lunar surface

Published literature suggests that water ice might be unambiguously detected in the presence of background contaminants by developing a frequency swept sensor to obtain the dielectric spectrum. Such a sensor could be incorporated into the tip of a spike and driven into the lunar regolith to detect moisture as a function of depth. A sensor was created to test this concept for varying concentrations of ice in lunar soil simulant under vacuum conditions. Ice relaxation occurs at frequencies well below 1 Hz at temperatures present on the Lunar surface, making it difficult to distinguish ice from the surrounding regolith. So, a heating element was incorporated with the sensor to capture the dielectric spectra as the ice warms, allowing the relaxation to be detected in a shorter period of time. The test results show the ability of this sensor to detect the presence of varying quantities of ice in the soil simulant and the need for more complex non-linear mixing models to quantify the amount of ice present in the mixture.