Christmas greetings from Mars

View of the Martian Angel with a big heart at the South Pole

These current images from the DLR Mars camera HRSC show a dune field and several periglacial landforms in the southern polar region of Mars. So much for the factual description of the picture content. But you can also see an angel and a big heart, which were formed from dark sands. Just as if our neighboring planet had got ready for the Christmas season.

Since January 2004, the HRSC (High Resolution Stereo Camera) has been mapping the red planet in high resolution, three-dimensional and in color as part of the ESA Mars Express mission. It was developed at the German Aerospace Center (DLR), built together with German industrial partners, and is operated at the DLR Institute for Planetary Research. Mars Express provides new data on the geology, mineralogy and atmosphere of Mars to gain insight into its climatic history and to clarify the role and fate of water.

Only the summer at Mars’ South Pole allows angels and hearts to become visible

But back to Mars: the angel and the heart, both made of dark volcanic sands, are located in the south polar region of the planet, not far from the polar cap, at around 78 degrees south. It’s summer there at the moment. The permanent ice cap, which consists essentially of water and carbon dioxide ice, is now 400 kilometers in diameter and an average thickness of 1.5 kilometers. These are dimensions that are roughly comparable to the ice-covered island of Greenland on earth. However, it only has this size in the southern summer. During the six-month winter, the South Pole ice cap on Mars continues to expand, almost to 60 degrees south. But even in summer on the southern hemisphere of Mars, temperatures never rise above zero degrees Celsius. In winter, temperatures of up to minus 133 degrees Celsius then freeze the carbon dioxide from the atmosphere and trickle as snow onto the ice cap. This blanket of carbon dioxide ice is between one and two meters thick andsublimates again with the next spring , thus evaporates, and exposes the landscape there again. Only a thin layer remains on the permanent ice cap of the South Pole. The Martian atmosphere contains very little water vapor, which can freeze and trickle down as ice: it is only 0.02 percent of the planet’s gas envelope, which consists mainly of carbon dioxide and nitrogen; on earth, with an average of 0.4 percent H 2 O, there is 20 times more water vapor in the atmosphere. The angel and the heart are only visible in the southern summer, in winter they are hidden under the carbon dioxide layer.

The angel’s head – an impact crater

In the upper center of the picture you can see an impact crater about 15 kilometers in size, in which dark sands form the “head of the angel”. With a little imagination, the almost thousand meter high rim of the crater can even be interpreted as a kind of halo. In several places the layered deposits of the polar cap, which consist of ice mixed with dust, are clearly visible on the upper slopes. Also in the oval hollow that forms the “hand of the angel”, the view of the layered polar deposits is free.

The southern area of ​​the image (on the right in Figures 1, 4, and 6) is also covered by layered deposits, which also consist of ice and dust, but are much more finely layered and less thick and cover the South Pole deposits. These types of deposits cover large parts of the high latitudes of Mars (approximately between 40 and 80 degrees north or south), which is why they are also called “latitude dependent mantle” in science. In many places in this mantle, signs of degradation due to erosion and sublimation of the ice in spring and summer can be seen, resulting in many small geological windows in which, on closer inspection, the finer layer structure can be seen.

In the center of pictures 1, 4 and 6, under the angel’s spread wing wing, there is a large heart-shaped depression, which is bordered by a steep slope to form another large, dark field of dunes. The dark material, which consists of olivine and pyroxene minerals, could have come from deeper layers of deposited volcanic eruption material or it could have been blown into the depressions. In the latter case, the edges of the terrain would have acted like wind breakers, whereby the sands were ‘slowed down’ and deposited there. This dark material is distributed globally on Mars and forms imposing dune fields in countless impact craters.

Dust devils “vacuum” the surface

On the left side of the picture, many dark, intersecting lines can be seen on a very flat and light surface. These are dust devil tracks , i.e. paths of numerous windpants that were created by atmospheric turbulence. By “sucking up” the lighter surface dust, they leave behind such dark traces on their way.

A Christmas angel “with a heart” greets from Mars’ South Pole

The existence of angels has not yet been scientifically documented for our neighboring planet Mars. Here on earth they are supposedly more present, especially in the Christian West. Their “appearance” is by no means restricted to the Christmas season. For example, you wish a “guardian angel” to all your relatives and loved ones and, last but not least, to yourself for a lifetime. But they are much more present at Christmas than at other times of the year. And the Christmas story from the Bible belongs above all to the Christmas season. An angel plays an important role in it. He brings the shepherds the good news of the birth of Christ, which begins with the famous words: “Do not be afraid!”

All images in high resolution and other images from the HRSC can be found in the Mars Express image gallery on flickr.

  • Image processing
    The recordings with the HRSC (High Resolution Stereo Camera) were taken on November 8, 2020 during Mars Express orbit 21.305. The image resolution is around 15 meters per image point (pixel). The center of the image is about 148 degrees east and 78 degrees south. The color overlay was created from the nadir channel, which is perpendicular to the surface of Mars, and the color channels of the HRSC, the perspective oblique view was calculated from the terrain model data, the nadir and color channels of the HRSC. The anaglyph image, which gives a three-dimensional impression of the landscape when viewed with red-blue or red-green glasses, was derived from the nadir channel and the stereo channels. The oversight, coded in rainbow colors, is based on a digital terrain model (DTM) of the region, from which the topography of the landscape can be derived. The reference body for the HRSC-DTM is an equipotential surface of Mars (areoid).The HRSC was developed at the German Aerospace Center (DLR) and is operated from there. The systematic processing of the camera data took place at the DLR Institute for Planetary Research in Berlin-Adlershof. Employees from the Faculty of Planetary Sciences and Remote Sensing at the Free University of Berlin created the image products shown here.
  • The HRSC experiment on Mars Express
    The high resolution stereo camera was developed at the German Aerospace Center (DLR) and built in cooperation with industrial partners (Airbus, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). The science team led by the Principal Investigator (PI) Prof. Dr. Ralf Jaumann consists of 50 co-investigators from 35 institutions and 11 nations. The camera is operated by the DLR Institute for Planetary Research in Berlin-Adlershof.

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