Electromagnetic characterization of a crushed L-chondrite for subsurface radar investigations of solar system bodies

Brin, Alessandro; Lauro, Sebastian; Cosciotti, Barbara; Mattei, Elisabetta; Pettinelli, Elena

doi:10.1016/j.icarus.2021.114800

Cited by 2 publications

(3 citation statements)

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“…Uncertainties have been calculated according to Brin et al. (2022) but are not visible in the plots as they are smaller than the symbols. The abrupt drop in permittivity values is due to water/ice phase transition; black dashed lines indicate the temperature at which the transition phase of pure water occurs.…”

Section: Resultsmentioning

confidence: 99%

“… Results from the slow temperature ramping tests conducted on the dry STx‐1b dry sample, showing the (a) real and (b) imaginary parts of the relative dielectric permittivity as a function of frequency at 220 K. Uncertainties have been calculated according to Brin et al. (2022). …”

Section: Resultsmentioning

confidence: 99%

“…In Equations A4 and A5 𝐴𝐴 𝐴𝐴𝑔𝑔 = 𝑍𝑍𝑐𝑐∕𝑍𝑍𝑝𝑝 is a geometrical factor accounting for the mismatch between the impedance of the coaxial cable 𝐴𝐴 𝐴𝐴𝑐𝑐 and the impedance of the coaxial-cage line in air 𝐴𝐴 𝐴𝐴𝑝𝑝 , 𝐴𝐴 𝐴𝐴 is the electrical length of the coaxial-cage line, f is the frequency and 𝐴𝐴 𝐴𝐴 is the velocity of the electromagnetic wave in a vacuum (see Figure A1b). We estimated the coaxial line 𝐴𝐴 𝐴𝐴𝑔𝑔 and 𝐴𝐴 𝐴𝐴 parameters as a function of temperature and frequency first measuring the probe line empty (air) (Brin et al, 2022), then using reference materials like bidistilled water and pure ethanol, following the procedure described in Mattei et al (2013). Moreover, before each set of measurements, a calibration procedure was performed using the SOLT standards (Short, Open, Load, Through) HP 85032F calibration kit.…”

Section: Appendix Amentioning

confidence: 99%

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Can Clay Mimic the High Reflectivity of Briny Water Below the Martian SPLD?

et al. 2023

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It has recently been suggested that clay minerals, which are widespread on the Martian surface, could be the possible source of the basal bright reflections detected by MARSIS at Ultimi Scopuli, instead of briny water. This hypothesis is based on dielectric measurements on a wet Ca‐Montorillonite (STx‐1b) sample conducted at 230 K, which reported permittivity values (apparent permittivity of 39 at 4 MHz) compatible with the median value of 33 retrieved by MARSIS 4 MHz data inversion in the high reflectivity area. These experimental results are, however, incompatible with well‐established dielectric theory and with laboratory measurements on clays, at MARSIS frequency and Martian temperatures, reported in the literature. Here, we replicate the experiment using a setup to precisely control the rate of cooling/warming and the temperature inside and outside the clay sample. We found that the rate of cooling, the position of the temperature sensor and, consequently, the thermal equilibrium between the sample and the sensor play a fundamental role in the reliability of the measurements. Our results indicate that even for a large water content in the clay sample, at 230 K and 4 MHz, the apparent permittivity is only 8.4, dropping to 4.1 at 200 K, ruling out clays as a possible source of the bright reflections detected by MARSIS at the base of the SPLD.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%