Broadband Measurements of the Complex Permittivity of Carbonaceous Asteroid Regolith Analog Materials

Abstract

AbstractWe develop a full methodology to measure the complex relative permittivity of planetary regolith analog materials in vacuum and up to 120 °C over a broad range of frequencies (400 MHz to 8.5 GHz or wavelengths 18.8–3.5 cm). We demonstrate our method with measurements of analog regolith materials appropriate for asteroid (101955) Bennu, the target of National Aeronautics and Space Administration's OSIRIS‐REx mission: individual and mixed components of UCF/DSI‐CI‐2, a new carbonaceous asteroid regolith simulant produced by Deep Space Industries based on CI chondrite meteorite mineralogy. We measure, for the first time, the effect of carbonaceous material on the complex relative permittivity of asteroid regolith analogs by measuring the powdered serpentine component of the simulant mixed with varying amounts of carbonaceous material in vacuum at 25 and 40 °C. We find that at a bulk density of 1.60 g/cm3 and wavelength of 12.6 cm, serpentine with 5 wt% carbonaceous material has = 3.30 ± 0.01 and = 0.016 ± 0.003 and that carbonaceous material increases the attenuation of electromagnetic energy in our samples. Ground‐based radar (at 12.6‐ and 3.5‐cm wavelengths) has previously been used to investigate carbonaceous asteroid (101955) Bennu. Our measurements provide new constraints on the attenuation of radar energy in granular carbonaceous materials.