Simulations for Martian subsurface' detection with radar sounder

Abstract

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.