Dielectric Properties of Lunar Simulant Materials

To guide development of microwave process technology that could be used during in situ construction on the Moon, basic dielectric measurements of εʹ and εʺ to high temperatures were acquired on 21 lunar simulants and related materials. In order to confidently use these data one needs to understand the data’s strengths and weaknesses. Therefore, a major point of this publication is to provide insight into the comparative significance of such things as sample pre-treatments, experimental variables, compositional differences, mixes of materials, and other considerations affecting this type of data. This work also is intended to be a permanent, public archive of data on which other workers can build. The dielectric measurements were performed using the cavity perturbation method. Measurements were taken over a temperature range between room temperature to ~1000 °C or higher, and provided the real and imaginary components of permittivity at six frequencies. Each set of measurements were provided in reports and data in ASCII files. In addition to the measurements the reports contained substantial ancillary information, such a photos and details of each run. The utility of the reported values was limited by the varying density of the pellets used in the measurement. Therefore, all of the εʹ and εʺ measurements at the frequency of 2466 MHz have been scaled to a constant density, 1.75 g/cc. For each material this document contained the original and scaled εʹ, εʺ, and the computed Half Power Depth versus temperature, the original Microwave Properties North reports, plots of scaled εʹ and εʺ versus temperature, and brief commentary. The plots were organized to aid analysis within the groups and across the datasets. To gain additional insight into the processes happening at the elevated temperatures of the dielectric measurements, differential scanning calorimetry (DSC) data on several of the simulant materials was also included.