P016-0002
Assessment of features within the south polar layered deposits of Mars with 3D radar imaging

Tuesday, 8 December 2020
Poster
Aaron Townes Russell1,2, Nathaniel E Putzig1, Jennifer L Whitten3 and Nadim Abu Hashmeh3, (1)Planetary Science Institute, Lakewood, CO, United States, (2)Colorado School of Mines, Space Resources, Golden, CO, United States, (3)Tulane University of Louisiana, New Orleans, LA, United States
Abstract:
The variability of the Martian Late Amazonian climate is recorded in the north and south polar layered deposits (PLD). The PLD contain mixtures of ice and dust, and radar sounding results have shown them to be predominately composed of water ice. Relative to the NPLD, the SPLD is much more attenuating of the Mars Reconnaissance Orbiter Shallow Radar (SHARAD) signal, including in some of its thinnest and thickest regions. We investigate this radar behavior to better understand the structure and composition of the PLD and the surface and climatic processes recorded by them.

We used the Planum Australe 3D (PA3D) volume data, produced using 2093 SHARAD tracks in the south polar region, to map the basal reflector of the SPLD everywhere that the signal penetration allows. Our procedure involves tracing subsurface reflectors that either originate at the edge of the SPLD or can be correlated to ones that do. Prior studies have identified areas of very low returned radar power within the SPLD that are known as low reflectivity zones (LRZ). These facies are located at the top of the stratigraphic column and contain no more than 2 internal reflectors. We mapped the base of all LRZ appearing in the PA3D data in our ongoing effort to characterize radar properties of the SPLD.

The thicker poleward portions of Australe Lingula and Promethei Lingula contain very few SPLD and LRZ basal reflections in the PA3D data. Even in some of the thinnest (< 1 km thick) regions of the SPLD (near 155°E, 190°E, and 270°E), the PA3D data show no reflectors and reveal very little detail about internal structure. These results, combined with our ongoing work to map the deepest reflectors visible throughout the SPLD, characterize the extent of the SHARAD signal attenuation in the PA3D data, and the correlation between the amount of attenuation and the LRZ. Ultimately, comparing these results to other radar datasets will more fully determine the cause of radar attenuation.

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