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Published November 2022 | public
Journal Article

New Views of the Internal Structure of Planum Boreum from Enhanced 3D Imaging of Mars Reconnaissance Orbiter Shallow Radar Data

Abstract

We present first results from a new 3D radargram produced from 3399 Mars Reconnaissance Orbiter (MRO) Shallow Radar observations of the north polar region of Mars. While incorporating an additional 5 yr of observations relative to the prior 3D radargram, we employed surface-clutter simulations to improve the coregistration of the input data and thereby enhance the effective vertical resolution of features. Combining those improvements with the geometric corrections and an increase in signal-to-noise ratio afforded by the 3D imaging process, this data product provides new details about the interior of Planum Boreum, the Martian north polar cap. We assess the overall characteristics and compare portions of the new 3D radargram to results from prior studies that used either the prior 3D radargram or sets of 2D radargrams from individual MRO orbits. We find that the new 3D radargram has recovered essentially all of the vertical resolution inherent to the input data, and the increased coverage density has substantially reduced artifacts while enabling much greater detail in the imaging of subsurface layering and structures. These improvements extend throughout the 3D radargram, from the basal units to the shallowest subsurface layering in Planum Boreum, and out into the surrounding plains. Subsurface features such as a buried chasma, other layering structures and unconformities, and trough-bounding surfaces that offset shallow layering are now visible in unprecedented detail. A thorough analysis of this new 3D radargram and its implications for the geologic and climate history of Planum Boreum will extend over many years.

Additional Information

We are grateful to NASA, ASI, the MRO Project, and the SHARAD Team for ongoing support of this incredibly successful mission and instrument. We also thank SeisWare for academic licenses to GSW, used in analysis of 2D and 3D radargrams, and Halliburton Landmark for licensing of their ProMAX/SeisSpaceTM data processing software, used in the generation of the 3D radargrams. We greatly appreciate positive and constructive comments provided by two anonymous reviewers and the PSJ Data Editor that improved the manuscript. Access to processing tools used to produce the long-aperture 2D radargrams are publicly available via the Colorado Shallow Radar Processing System (CO-SHARPS). CO-SHARPS access instructions and the 3D radargrams are available through the US SHARAD Team's website at https://sharad.psi.edu. The original Planum Boreum 3D radargram is also available through the NASA PDS Geosciences node (Putzig et al. 2021), and the new one is in delivery and will be made available online at https://doi.org/10.17189/a5av-yc11. This work was supported predominantly by NASA Mars Data Analysis Program grant NNX16AN90G, and additional support in completing this manuscript was provided by the MRO Project. Participation by I.H.M. was made possible through the Jefferson County Colorado High School Executive Internship Program.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023