Laboratory investigations into the electromagnetic properties of magnetite/silica mixtures as Martian soil simulants

Abstract

[1] In this paper a set of frequency domain (500 Hz to 1 MHz) experimental data on electrical and magnetic parameters of magnetite/silica mixtures as Martian soil simulants is presented. Complex permittivity was obtained by measuring the magnitude and phase of the electrical impedance of a capacitive cell filled with the tested material. Complex magnetic permeability was obtained by measuring the impedance of a toroid fully embedded in the mixtures. Both the permittivity and magnetic permeability exhibited an appreciable increase with the magnetite volume fraction and a complex behavior with grain size and origin. Furthermore, to assess the possibility of extending the data acquired at 1 MHz to higher frequencies (tens to hundreds of MHz), some comparisons were made between these data and Time Domain Reflectometry measurements. Finally, the attenuation versus magnetite volume fraction and frequency (in a band consistent with the MARSIS and SHARAD sounders) was computed for various types of magnetite/silica mixtures. The results indicate that in a dry soil which contains a significant fraction of magnetic material both the wave velocity and the attenuation are a combination of different factors, including the dimension, shape, and origin of the magnetic material.

Effects of magnetite on high-frequency ground-penetrating radar

“…All three studies show a significant decrease in velocity with increasing amount of magnetite (Figure 10a). The data by Pettinelli et al (2005) and Cassidy (2008) are nearly identical. The data by Cassidy, which like the present study cover the full range of distributions from 0% to 100% magnetite, display a slight nonlinear response.…”

“…The relative permittivity of the magnetite is much higher and shows strong frequency dependence in real and imaginary components. A similar increase at low frequencies is observed by Cassidy (2008) and Pettinelli et al (2005). At the center frequency of the GPR signal (1.08 GHz), the relative permittivity of the magnetite is around 8.4 (Figure 3a).…”

“…The magnetite used was a commercially available kind at nano-to-micro grain sizes. Pettinelli et al (2005) performed measurements of the electromagnetic wave velocity of magnetite-silica mixtures with a volume percent range of 0%, 5%, 10%, 15%, 20%, and 25% magnetite (0%, 9%, 17%, 25%, 32%, and 39% magnetite when converted to weight percent). The magnetite had grain sizes ranging from 200 to 500 μm, and was extracted from a beach (similar to the sample material used in this study).…”

“…As has been shown in a few recent theoretical and laboratory studies, these altered electromagnetic properties may, in turn, lead to considerable changes in signal propagation at GPR-specific frequencies. For example, measurements of electromagnetic wave propagation through magnetite-silica mixtures using time-domain reflectometry (TDR) demonstrated that the presence of magnetite leads to a significant decrease in electromagnetic wave velocity (Mattei et al, 2005;Pettinelli et al, 2005). Recent measurements of electromagnetic properties for similar magnetite-silica mixtures using a vector network analyzer (VNA) showed a strong frequencydependent effect of magnetite on propagation velocity and signal attenuation (Cassidy, 2008).…”

Permittivity estimation of layers beneath the northern polar layered deposits, Mars

“…The trachy-basalt volumetric fraction content f is assumed equal to 8%; this value has been chosen according to Grima et al [2009]. The dielectric parameters of ice have been chosen according to [Chyba et al, 1998, Nunes andPhillips, 2006] at the temperature of 200K, whereas the dielectric properties of trachy-basalt have been chosen on the basis of the measurements in the lab (@ 1MHz) using L-C-R meters [Pettinelli et al, 2005]. With these assumptions," 1 = 3.3 − j0.003.…”