Measurements of dielectric loss factors due to a Martian dust analog

Abstract

[1] Radar signals can penetrate loose sediments such as dust, sand, and alluvium to reveal buried geologic structures obscured in visible and infrared images. In anticipation of data from instruments such as the MARSIS and SHARAD radar sounders and potential future imaging SAR and rover-mounted GPR instruments, measurements have been made to characterize electrical loss factors of a Martian dust analog and an iron-rich soil. This paper presents results from dielectric measurements of Carbondale Red Clay (CRC) and the palagonitic Mars JSC-1 soil simulant from 0.2 to 1.3 GHz and from transmission measurements of radar penetration of CRC up to 12 GHz. Attenuations predicted from dielectric measurements are compared to values measured in the experiment and are discussed relative to the frequencies at which imaging radars operate. Over the frequencies considered, loss tangent, tan d, decreases with increasing frequency, but attenuation increases due to the influence of wavelength. Attenuation in CRC ranges from 8 to 22 dB/m over P and L bands and jumps to 36 and 67 dB/m at C and X bands, respectively. Mars JSC-1 has lower attenuation of 5 dB/m at P band and $12 dB/m at L band. Compared to attenuation measurements of sand, both CRC and Mars JSC-1 cause significantly greater attenuation, likely due to their compositions containing iron-bearing minerals. Because Martian fine sediments also contain ferric mineral components, constraining higher losses of analogs for Martian dust and fine sediments is important for predicting the performance of radar instruments operating in orbit or on the surface of Mars.

Permittivity of porous granular matter, in relation with Rosetta cometary mission

“…Our results for ϵ 0 are consistent with these measurements, whereas we find somewhat larger values for ϵ″ for all frequencies and grain size ranges. Measurements have also been made between 0.20 and 1.30 GHz using three radar emitter/receiver sets mounted in transmission (Williams and Greeley, 2004). These measurements are in agreement with our measurements, with ϵ 0 equal to about 3.18 at 0.50 GHz and 3.09 at 1.24 GHz, and with rather stable high values of ϵ″, around 0.20.…”

“…These measurements are in agreement with our measurements, with ϵ 0 equal to about 3.18 at 0.50 GHz and 3.09 at 1.24 GHz, and with rather stable high values of ϵ″, around 0.20. Williams and Greeley (2004) mentioned that the high values of ϵ″ measured for the JSC Mars-1 simulant, that we also obtained, may be due to the relatively high content of the Mars simulant in iron oxide which is a lossy material (involving a greater attenuation of the signal).…”

Ground penetrating radar geologic field studies of the ejecta of Barringer Meteorite Crater, Arizona, as a planetary analog

“…In such an environment, where postreflection waves may be disrupted before returning to the transceiver, larger objects have a better chance of returning a coherent radargram feature. These results augment suggestions that GPR waves in planetary volcanic terrain may suffer composition‐dependent attenuation [ Paillou et al ., ; Heggy et al ., ; Stillman and Olhoeft , ; Williams and Greeley , ; Pettinelli et al ., ] by demonstrating that penetration may be limited at least as severely by near surfaces crowded with structural scatterers. Similar conclusions have been drawn based on poor radar returns at depth recorded from beneath impact‐crater breccia at Haughton impact crater [ Unrau et al ., ], due to fractured bedrock at small impact craters in the Egyptian desert [ Heggy and Paillou , ], and in the heterogeneously welded Bishop Tuff [ Grimm et al ., ].…”

JMSS-1: a new Martian soil simulant

“…Measurements of the dielectric properties of Martian soil simulant and other materials can help to anticipate radar performance on Mars, because radar signal penetration is influenced by the dielectric properties of the penetrated materials (Olhoeft and Capron 1993;Williams and Greeley 2004). The dielectric constant (ε′) and loss (tanδ) of JMSS-1 at 9370 MHz are about 5.9 and 0.07 (accuracy < 3 %), respectively.…”