Analysis of water ice volume from 3D radar imaging of lobate debris aprons on Mars

A common practice with terrestrial geophysical data is to produce 3D images where coverage densities are sufficient. Previous work has produced 3D images from Shallow Radar (SHARAD) observations of the poles of Mars [Foss et al., 2017, doi:10.1190/tle36010043.1] where coverage is extremely dense. Mid-latitude ice on Mars is of high interest for both climate studies and space resources, and our work focused on assessing results from a new 3D SHARAD image within Deuteronilus Mensae. At Fresnel zone resolution (3 km), coverage in the study area is ~ 87%, and at the 3D binning resolution (475 m), coverage is ~ 16%. Using the techniques of Foss et al. [2017], we produced the Deuteronilus Mensae 3D (DM3D) radar image to study the structure and ice content within lobate debris aprons (LDAs) Fig. 1. Using the DM3D image, we find that the LDAs in the study area contain ~ 15,000 km3 of ice. Compared to prior work by Peterson et al. [2018, doi:10.1029/2018GL079759] using 2D data, this is an increase of ~ 80% in ice volume that is attributable to improvements in basal detection and structural accuracy afforded by the 3D imaging. Our results demonstrate that the production of 3D images at mid-latitudes where 475-m-scale coverage is as low as ~ 16% will yield significant improvements over that possible when using the 2D data alone. The DM3D coverage density is near the lower bound for producing effective 3D images, and artifacts seen in cross-track views of the DM3D image indicate that increasing coverage densities up to ~100% at this scale will yield increasingly higher fidelity products. Mid-latitude locations of ice have been the subject of much investigation by the space resources community in preparation for future manned missions to Mars [e.g. Putzig et al., this meeting]. Subsurface investigations enhanced through 3D radar processing, enable future investigators to better prepare for the necessary technology development and science for a sustainable human presence on Mars. Such areas of interest that do not currently have SHARAD coverage > 16% would greatly benefit from targeting to acquire additional data. Fig. 1 shows a portion of Deuteronilus Mensae. Our mapping of the LDAs is shown in blue and to the left of the green line, and previous work done by Peterson et al. [2018, doi:10.1029/2018GL079759] is shown in red.