Scientific calibration of SHARAD data over Martian surface

Abstract

SHARAD (SHAllow RADar) is the subsurface sounding radar provided by the Italian Space Agency (ASI) as a facility instrument to NASA's 2005 Mars Reconnaissance Orbiter (MRO). The main activity of SHARAD is to make significant new scientific data available toward on Mars, including subsurface layering and an improved understanding of the electromagnetic properties of the surface regions, further insights into the nature of patterned ground, and other morphologies suggestive of the presence of water at present or in the past[1]. The goal of this paper is to describe the method developed for correlating the data to the Martian surface permittivity. The North polar cap has been used as reference back-scatterer, in this area the data indicate an almost pure water ice composition, and thus whose dielectric properties are known [2]. An automatic procedure to estimated the other factor contributing to surface echo strength, i.e. scattering due to surface roughness, has been developed and the fitting of the data to a theoretical model based on fractal geometry has been performed. The result presented is the possibility of estimate the permittivity of Mars surface from the set of radar back-scatterer measurement and the possibility to produce maps of the dielectric constant of the Martian surface and detailed reconstruction of the surface material of Mars.