Automated reconstruction of subsurface interfaces in Promethei Lingula near the Martian south pole by using SHARAD data

J.-P Muller,S Xiong

doi:10.1016/j.pss.2018.08.001

Abstract

Subsurface layers are preserved in polar regions on Mars, which are considered to be a record of past climate changes on Mars. Orbital radar instruments like the SHAllow RADar (SHARAD) on board Mars Reconnaissance Orbiter (MRO) transmit radar signals to Mars and receive a set of signals returned from interfaces having a contrast in dielectric properties in the probed subsurface regions. These subsurface layers which are preserved in the upper ≈ 1 km of the Martian Polar Layered Deposits (PLDs) can be observed in SHARAD radargrams. Extraction of these layering features is the preliminary work before interpreting and understanding their origins. In this study, we use a new method based on log-Gabor filtering and Continuous Wavelet Transform (CWT)-based peak detection to extract subsurface radar reflections and a workflow to remove clutter reflections in order to reconstruct 3-D subsurface layers. These methods and workflow are then tested on the SHARAD data in the Promethei Lingula region near the Martian south pole. The results show that following this workflow, the ground surface and six subsurface interfaces can be reconstructed, which aids in the interpretation of the depositional and erosional history of this region.

Highlights

Radar sounding techniques were proposed in the 1960s for investigating subsurface areas of glaciers on Earth
The SHAllow RADar (SHARAD) radargram from orbit 2202, which is shown in Fig. 3(a), is here used to illustrate the results of the log-Gabor filtering
The log-Gabor filtering is applied to this subset radargram and the result is shown in Fig. 3(b), along with filtering results by Block-Matching and 3D (BM3D) (Fig. 3c) and Bilateral filtering (Fig. 3d)

Summary

Introduction

Radar sounding techniques were proposed in the 1960s for investigating subsurface areas of glaciers on Earth. It is a non-intrusive and direct imaging technique to obtain subsurface information, which is different from surface imagery that only provides surface features from which one may be able to infer subsurface conditions. The radar sounders transmit waves to the probed regions and record the backscattered signals. The resultant images acquired by using the radar sounders are called radargrams, in which the x-axis represents the geographical locations of the profiles and the y-axis is the two-way travel (TWT) time. Each of the TWT time signals (each column in a radargram) represents a series of radar reflections, which may indicate changes in the dielectric boundaries underground

Methods

Results

Discussion

Conclusion