The German Aerospace Center (DLR) recently published new images taken by the Mars Express spacecraft, revealing a winter landscape on the Red Planet. The pictures depict a late winter scene in the Australe Scopuli region near Mars' south pole, displaying an icy world covered in carbon dioxide ice and dust.
Launched in 2003, the Mars Express mission has been providing images of Mars for two decades. During its 23,324th orbit, the spacecraft captured visuals of the Australe Scopuli region. The images were taken with the High Resolution Stereo Camera (HRSC), developed at the DLR Institute of Planetary Research.
The images reveal a landscape where carbon dioxide ice forms patterns of dust and frost. The darker areas in the images represent layers of dust that have settled on top of the ice, creating a contrast with the bright carbon dioxide ice. This contrast is especially noticeable on the exposed slopes and in the valleys of the region.
Mars' snow is made of carbon dioxide ice, not water ice. During the Martian winter, temperatures can drop to as low as minus 190 degrees Fahrenheit (minus 123 degrees Celsius), which does not allow the formation of much more than a few centimeters of snow. The Australe Scopuli region remains cold year-round.
In June 2022, the European Space Agency's Mars Express orbiter captured images of a snowy landscape in the Australe Scopuli region, where the "snow" is actually carbon dioxide ice. The Sun causes the seasonal ice layers to retreat, leading to sublimation in the lower layers as the upper layer melts.
As the ice sublimates, pockets of trapped gas form within the ice. The pressure builds up until the overlying ice suddenly bursts, resulting in an eruption of gas that shoots through the surface. The gas carries dark dust with it, which falls back onto the surface in a fan-shaped pattern formed by the direction of the prevailing wind. These gas fountains can carry dust that settles in patterns shaped by wind currents.
This process forms fan-shaped patterns on the Martian surface, caused by winds creating boundaries between different layers of deposits. Similar reactions on the Martian surface can form features in the shapes of spiders, fried eggs, lace, and halos, with a similar process creating the spider-like formations found on Mars.
The contrasting light and dark layers in the images are the result of alternating deposits of bright carbon dioxide and water ice with dark sands, typical of the region. These layers result from frozen ice mixed with varying amounts of dust. The Australe Scopuli region features a 500-kilometer-long ice formation composed of frozen carbon dioxide.
Mars Express has been providing images that reveal the chemical composition of Mars' atmosphere, in addition to visual effects. The mission has also offered detailed observations of Mars' moons, Phobos and Deimos. Furthermore, it has helped in understanding the history of water on Mars.
The average temperature on Mars is minus 60 degrees Celsius, and there is insufficient oxygen in the Martian atmosphere for breathing. The land in the images is slowly acclimating to the Martian summertime, although the temperature is still minus 193 degrees Fahrenheit (minus 125 degrees Celsius).
As sunlight warms the carbon dioxide ice on Mars' south pole in the summer, the ice begins to sublimate, transitioning from a solid to a gaseous state and expanding. This process creates gas pockets as solar light penetrates the translucent upper layers of ice, causing the ice at the base to sublimate.
Eventually, the pressure builds enough to create a gas eruption powerful enough to blast the dark dust found beneath the ice into the air. These gas fountains carry dark dust that falls back onto the surface in fan-shaped patterns formed by prevailing winds. The fans can vary from tens to hundreds of meters in length.
As the dust settles, the wind shapes it into swirling patterns, forming distinct formations on the ground. The swirling patterns are created when the Sun's radiation warms the dark areas underneath the ice before the ice melts. As the dust falls back to the surface, the wind shapes it into these patterns.
Under the ice cover, pressure increases, and jets shoot upward. These jets bring a lot of dust with them, depositing it on the ice. On the left side of the images, numerous dark spots can be seen where the ice has already sublimated, turning directly from solid ice into vapor.
The images show alternating layers of ice and dust that are clearly visible in the view of icy hills in the Australe Scopuli region. A view of an icy valley on Mars resembles an earthly ski slope, complete with tracks in the snow. Hundreds of closely packed, dark fan-shaped patterns mark the edges of the layered deposits in the valley.
T-Online, Space.com, and Astronomy Magazine reported on the new images, among other websites.
This article was written in collaboration with generative AI company Alchemiq