Martian northern polar cap: Layering and possible implications for radar sounding

Ilyushin, Ya. A.

doi:10.1016/j.pss.2004.08.002

Cited by 15 publications

(18 citation statements)

References 38 publications

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“…Although radiative transfer in such media in astronomical applications [6] has been studied since the middle of the last century and radiative heat transfer in refracting media is now an important technical task [7][8][9], coherent backscattering enhancement in such media in fact has not been widely investigated. However, it is important in some applications dealing with backscattering from these media [3], e.g., radar probing of ionospheric and solar plasma [10,11] and terrestrial and planetary ice and snow covers [12].…”

Section: Introductionmentioning

confidence: 99%

Coherent backscattering enhancement in refracting media: diffusion approximation

Ilyushin¹

2013

J. Opt. Soc. Am. A

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Section: Introductionmentioning

confidence: 99%

Coherent backscattering enhancement in refracting media: diffusion approximation

Ilyushin¹

2013

J. Opt. Soc. Am. A

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“…The material of the SPLD is widely believed to be mixtures of eolian deposits and ice [ Clifford et al , 2000; Titus et al , 2003; Bibring et al , 2004; Ilyushin , 2004]. Laboratory experiments on the Earth analogs of the ice‐dust mixtures show that the real part of the dielectric constant ranges from 3.1 for pure ice to 4.8 for an ice sample with a 75% basaltic dust content [ Heggy et al , 2006].…”

Section: Resultsmentioning

confidence: 99%

Dielectric properties of the Martian south polar layered deposits: MARSIS data inversion using Bayesian inference and genetic algorithm

et al. 2008

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[1] Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) has offered abundant data, which have been used to estimate dielectric properties of the south polar layered deposits (SPLD) of Mars. This paper presents a new way to invert the data to estimate the dielectric properties of the SPLD. A total of 4364 measurements were analyzed. The received radar signals are controlled by the physical properties of the SPLD and its basal layer and in addition by a number of factors including the transmitted wave properties, the satellite height, and the atmosphere/ionosphere environments. The received signals may also be influenced by surface clutter. Most of these factors are variable. This complexity causes the inversion to be difficult. To carry out the inversion, it is therefore essential to define a reasonably simple model for the physics of the surface/ subsurface layers where the radar signal is reflected. The top and bottom interfaces of the SPLD are observed by MARSIS as two reflection peaks of the radar signals. The intensity ratio between the two reflection peaks is observed to be a function of the time difference separating the two peaks. By modeling this dependency, the influences of the satellite position and the atmosphere/ionosphere environments are canceled. This is a major step toward carrying out the inversion. Nevertheless, the inverse problem remains ill-posed and highly nonlinear. Bayesian inference is employed to deal with the ill-posed aspect of the inversion, and genetic algorithm is introduced to deal with the nonlinearity. It is concluded that the most probable value of the relative dielectric constant of the SPLD lies in 3.0-5.0, conductivity 1.0-2.0 Â 10 À6 S/m, and the relative dielectric constant of the basal layer is 7.5-8.5 (The basal layer conductivity is assumed to be 1.0 Â 10 À7 S/m.) These results support a suggestion that the SPLD are water ice/dust mixtures with dust content varying from 0 to more than 75%.

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“…The permittivity of layer 2 can also be evaluated from the surface and subsurface echo received by radar. The surface of Martian north polar cap is gently undulating with a very small roughness while the roughness of southern polar cap is higher [9][10][11][12]. The wavelength of electromagnetic wave emitted by the radar sounder on board the satellite orbiting around Mars is about 10m~100m, which satisfies the Kirchhoff approximation(KA) compared with the roughness of Martian surface.…”

Section: Models and Methodsmentioning

confidence: 98%

Simulations for Martian subsurface' detection with radar sounder

Zhang

Fang

2012

2012 14th International Conference on Ground Penetrating Radar (GPR)

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The poles of Mars are cold traps for Martian atmospheric volatiles. The layered structures of polar deposits are thought to represent a record of Martian climatic history. In this paper, the propagation of electromagnetic waves in the polar caps is considered. Kirchhoff approximation and geometrical optics method are adopted to simulate the radar echo from Martian gently undulating surface and subsurface. The radar is modulated with linear frequency-modulated signals. Location information of the Martian surface and subsurface is obtained by a signal processing of radar echoes using pulse compression method. Simulation-based results show that the method presented is feasible in the detection of Martian polar cap regions' layered structure. Comparisons of radar echoes from surfaces with different roughness are investigated. It is revealed that the received echo gets weaker with the increasing of the Martian surface's roughness and the subsurface nadir echo is gradually immersed among surface clutters. These results provide a better understanding to the nature of reflection and refraction of electromagnetic waves at Martian surface and subsurface. The changes of echoes from layered structures with different conductivity and permittivity are also investigated and analyzed, which can provide some important clues for the radar system designers to determine the detection ability of radar sounder.

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Martian northern polar cap: Layering and possible implications for radar sounding

Cited by 15 publications

References 38 publications

Coherent backscattering enhancement in refracting media: diffusion approximation

Coherent backscattering enhancement in refracting media: diffusion approximation

Dielectric properties of the Martian south polar layered deposits: MARSIS data inversion using Bayesian inference and genetic algorithm

Simulations for Martian subsurface' detection with radar sounder

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