Uncovering a High-Resolution Climate Record in the Martian North Polar Layered Deposits

The North Polar Layered Deposits (NPLD) of Mars consist of many interbedded layers of dusty ice and are thought to be approximately 4 million years old. It is believed that the layers record variations in the rates of ice and dust accumulation over time, which are driven by changing orbital conditions. These layers also result in dozens of sub-parallel reflectors in orbital radar sounding data acquired by the Shallow Radar (SHARAD) on board the Mars Reconnaissance Orbiter (MRO). However, efforts to tie layer or reflector properties to specific climate conditions have largely been inconclusive. One of the major stumbling blocks is a lack of information regarding layer composition and how it changes both geographically and with depth. In order to fill this knowledge gap, we aim to produce a full record of fractional dust content over a large, continuous region of the NPLD.

The first step is to map radar reflectors across the study region. For this project, we are using the newly available super-resolution data, which has been reprocessed with advanced algorithms to produce observations with 3x the vertical resolution of standard data. This will ensure our record is as detailed and continuous as possible, and lessen the impact of interference caused by closely spaced layers. Once reflectors are mapped, their reflection power can be extracted and inverted to estimate fractional dust content using established modeling procedures. In addition to the one-layer model used in the past, we will also consider more complex multi-layer scenarios. The final product of this work will be a three-dimensional map of fractional dust content spanning a large region of the NPLD, and extending from the surface to the base of the deposit. In this presentation we will demonstrate our reflector mapping progress along with preliminary reflectivity measurements. We will also discuss the inversion procedure to be applied in the future.