Present-day mass wasting of the north polar ice cap on Mars

• Main Author: Su, Shu
• Other Authors: Oberst, Jürgen, Technische Universität Berlin, Hiesinger, Harald, Portyankina, Ganna
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2024
• Subjects: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften; Geologie::550 Geowissenschaften; 600 Technik; Medizin; angewandte Wissenschaften::620 Ingenieurwissenschaften::629 Andere Fachrichtungen der Ingenieurwissenschaften; mass wasting; erosion process; Mars; convolutional neural network (CNN); ice block falls; North pole; deep learning; change detection; scarp; planetary science; Ice cap; Nordpol*; North Pole
• Online Access: https://depositonce.tu-berlin.de/handle/11303/22120; https://doi.org/10.14279/depositonce-20921

Mars is a dynamic planet, exhibiting diverse active processes across its surface. Driven by variations in the obliquity of the rotation axis and the eccentricity of the orbit, the surface of Mars has experienced successive episodes of deposition and removal of water ice. At the end of the last ice age, about 0.4 Myr ago, water ice has finally deposited at the two poles, at the expense of loss from the mid-latitudes. Since then, these polar ice deposits have been undergoing reworking with erosion and retreat in response to climate change. In particular, at the north polar ice cap, prevalent surface changes, such as avalanches and ice block falls, have been observed from high-resolution satellite images. Ice block falls are likely the most active erosional process that are consistently affecting the topography of the north polar ice cap. Although avalanches are also prevailing, they are thought to carry mostly CO2 ice and dust. Research on how ice block falls have been shaping the north polar ice cap, are limited and incomplete. Therefore, in this work, I will address this interesting and significant task. The main efforts of this thesis are as follows. 1). I have designed a pipeline to process the High Resolution Imaging Science Experiment (HiRISE) raw images, generate HiRISE Digital Terrain Models (DTMs), and carry out orthorectification, by using the Ames Stereo Pipeline software. The produced DTMs generally conform to the criteria for orthorectifying raw images. This pipeline is crucial for this work as the orthorectified HiRISE images are essential for monitoring meter-scale changes at the north polar region through time. 2). I have proposed a solution to search for the sources of ice block falls at the marginal steep scarps of the North Polar Layered Deposits (NPLD). The idea is to identify the shadows of the detached ice-fragments, because the changes in shadow patterns can attest to ice block fall events. An automated intensity-based change detection method has been developed, and successfully applied to ...