The Convergence of Sand Dunes and Stacked Ice at Mars’s North Pole

ESA’s Mars Express spacecraft has captured a stunning image of the north pole of Mars, revealing the interaction between vast sand dunes and layers of icy dust covering the pole. The region, known as Planum Boreum, is covered in layers of fine dust and water ice that are several kilometers thick and extend for about 1000 km. Although most of this material is not visible in the image, the beginnings of Planum Boreum can be seen to the right of the frame, with subtle wrinkling indicating the buildup of layers of material. The topographic view of the region shows that the ground has built up in steps, with the lowest altitude regions appearing in blue/green and the highest in red/white/brown.

These layers have formed over time as a mixture of dust, water ice, and frost settled on the Martian ground. Each layer contains valuable information about Mars’s history, revealing how the planet’s climate has evolved over millions of years. During Martian winter, a thin cap of dry ice (carbon dioxide ice) forms on top of the layers, disappearing completely during summer. The image was captured by the Mars Express High Resolution Stereo Camera (HRSC) and shows two steep escarpments that mark the boundary between the layered deposits and the vast dune fields of Olympia Planum.

The left part of the image displays a vast expanse of rippled sand dunes, stretching for more than 150 km. These dunes have a wrinkled and turbulent appearance, contrasting with the smooth and pristine terrain on the right side of the image. The smooth region lacks signs of erosion and indicates a surface that is very young, rejuvenating every year. Situated between these two extremes are two semicircular cliffs, one of which is approximately 20 km wide. Frost-covered sand dunes are nestled within the curves of these cliffs, creating a dramatic scene. The cliffs’ icy walls reach heights of up to a kilometer and cast dark shadows on the surface below.

These cliffs are located in a polar trough, a feature that has been eroded by the wind. This erosion manifests as rippled ridges in the terrain and is common in this region, contributing to the unique spiral-like pattern of the polar plateau. Mars Express has been exploring Mars since 2003, capturing images of its surface, mapping its minerals, analyzing its atmosphere, studying its crust, and investigating various phenomena in the Martian environment. The HRSC has provided valuable insights into Mars’s diverse surface, including wind-sculpted ridges, sinkholes near volcanoes, impact craters, tectonic faults, river channels, and ancient lava pools. This mission has significantly increased our understanding of our neighboring planet. The HRSC was developed and is operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR).

To wrap it up, Mars Express’s recent image of Mars’s north pole has provided a captivating view of the interaction between sand dunes and icy layers. This image not only showcases the unique features of Mars’s polar region but also highlights the incredible work being done by the spacecraft in unraveling the mysteries of our neighboring planet. With each discovery, we move closer to a comprehensive understanding of Mars and its fascinating history.