17. December 2020
Mars Express mission

Sea­son's greet­ings from Mars

View of the Mars ‘angel’ with a big heart at the south pole of Mars
View of the Mars ‘an­gel’ with a big heart at the south pole of Mars
Image 1/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

View of the Mars ‘angel’ with a big heart at the south pole of Mars

The DLR High Res­o­lu­tion Stereo Cam­era (HRSC) has been map­ping the Red Plan­et in un­prece­dent­ed res­o­lu­tion, in three di­men­sions and in colour, since 2004 as part of ESA’s Mars Ex­press mis­sion. In im­ages record­ed on 8 Novem­ber 2020 dur­ing or­bit 21,305, a yet un­known, near­ly one-hun­dred-kilo­me­tre-long an­gel­ic fig­ure near the south pole of Mars ap­pears to want to greet Earth from a cur­rent dis­tance of ap­prox­i­mate­ly 100 mil­lion kilo­me­tres.
A perspective view of the angel on Mars
A per­spec­tive view of the an­gel on Mars
Image 2/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

A perspective view of the angel on Mars

The dig­i­tal ter­rain mod­els cre­at­ed us­ing im­age da­ta ac­quired by the stereo chan­nels of the HRSC in­stru­ment on ESA’s Mars Ex­press space­craft can be used to gen­er­ate per­spec­tive views of the land­scape on Mars. This view shows dark sand de­posits near the south pole of Mars. These out­lines are rem­i­nis­cent of an an­gel with out­stretched wings, with a large heart un­der its (from the cam­era’s per­spec­tive) right wing. On the left bor­der of the im­age, an im­pact crater ap­prox­i­mate­ly 15 kilo­me­tres wide can be seen, in which the dark sands form the ‘head of the an­gel’. With a lit­tle imag­i­na­tion, the al­most one-thou­sand-me­tre-high rim of the crater can be in­ter­pret­ed as a ‘ha­lo’. The dark ma­te­ri­al con­sists of al­most com­plete­ly black sands of olivine and py­rox­ene min­er­als and was prob­a­bly blown in­to the crater.
Mars with heart
Mars with heart
Image 3/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Mars with heart

In the night be­tween 24 and 25 De­cem­ber 2003, ESA’s Mars Ex­press space­craft reached its tar­get or­bit. For hun­dreds of tech­ni­cians, en­gi­neers and sci­en­tists at the ESA con­trol cen­tre in Darm­stadt, achiev­ing Mars or­bit was the best sea­son­al gift. Orig­i­nal­ly, the mis­sion was planned to ex­plore Mars for one Mar­tian year, which cor­re­sponds to two Earth years – that is, un­til the end of 2005. Be­cause of the out­stand­ing per­for­mance and re­li­a­bil­i­ty of all sev­en in­stru­ments, ESA ex­tend­ed the mis­sion again and again, most re­cent­ly un­til the end of 2022. Did the plan­et Mars, with its un­pre­dictable winds, want to give the ESA Mars Ex­press team and the HRSC sci­en­tists a lit­tle treat af­ter more than 25 years of plan­ning, im­ple­men­ta­tion and eval­u­a­tion, by ‘paint­ing’ a heart of dark min­er­al de­posits, dozens of kilo­me­tres in size, on the south po­lar re­gion? Who knows …?
The topography of an angel on Mars
The to­pog­ra­phy of an an­gel on Mars
Image 4/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The topography of an angel on Mars

DLR’s High Res­o­lu­tion Stereo Cam­era (HRSC) on board ESA’s Mars Ex­press space­craft, with its nine sen­sors ar­ranged across the north-south flight di­rec­tion, records the sur­face of Mars at dif­fer­ent an­gles and in four colour chan­nels. From the four stereo chan­nels and the nadir chan­nel, which is di­rect­ed per­pen­dic­u­lar to the sur­face of Mars, sci­en­tists at the DLR In­sti­tute of Plan­e­tary Re­search and the Freie Uni­ver­sität Berlin com­pute dig­i­tal ter­rain mod­els, which as­sign el­e­va­tion in­for­ma­tion to each pix­el. The colour scale in the up­per right cor­ner shows the dif­fer­ences in al­ti­tude in the re­gion. Here, the out­lines of the ‘an­gel on Mars’ with its out­stretched ‘wings’ stand out through the colour cod­ing.
The landscape near the south pole on Mars
The land­scape near the south pole on Mars
Image 5/6, Credit: NASA/JPL (MOLA); FU Berlin

The landscape near the south pole on Mars

Mars has per­ma­nent ice caps at both poles, which grow dur­ing the po­lar night of the win­ter on Mars due to the pre­cip­i­ta­tion of ice crys­tals from the at­mo­sphere. They shrink again at the end of the po­lar night due to warm­ing. With a di­am­e­ter of less than a thou­sand kilo­me­tres, the ice cap at the south pole is much small­er than the one at the north pole. In ad­di­tion to the ice, strong winds al­so shape the po­lar re­gions, erod­ing val­leys such as Promethei Chas­ma and Ul­ti­mum Chas­ma at the south pole – and de­posit­ing sand and dust trans­port­ed by the winds, which cre­ate new ge­o­log­i­cal for­ma­tions. The High Res­o­lu­tion Stereo Cam­era (HRSC) op­er­at­ed by the Ger­man Aerospace Cen­ter (Deutsches Zen­trum für Luft- und Raum­fahrt; DLR) im­aged the land­scape at ap­prox­i­mate­ly 80 de­grees south on 8 Novem­ber 2020 dur­ing or­bit 21,305.
3D view of an ‘angel’ on Mars with a big heart
3D view of an ‘an­gel’ on Mars with a big heart
Image 6/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

3D view of an ‘angel’ on Mars with a big heart

Anaglyph im­ages can be cre­at­ed us­ing da­ta ac­quired by the nadir chan­nel of the High Res­o­lu­tion Stereo Cam­era (HRSC) op­er­at­ed by DLR on board ESA’s Mars Ex­press space­craft (the field of view of which is aligned per­pen­dic­u­lar to the sur­face of Mars) and one of the four oblique-view­ing stereo chan­nels. When viewed with red-blue or red-green glass­es, these im­ages give a three-di­men­sion­al view of the land­scape. North is to the left of the im­age. Here, the to­pog­ra­phy of a strik­ing­ly out­lined land­scape struc­ture catch­es the eye, rem­i­nis­cent of an an­gel with out­stretched wings, un­der whose (from the cam­era's per­spec­tive) right wing a heart can be seen. The to­pog­ra­phy stems from ac­cu­mu­lat­ed de­posits of dark vol­canic sands, which can be eas­i­ly un­der­stood in the 3D view. With a lit­tle imag­i­na­tion, even the crater rim of the de­pres­sion that makes up the ‘head of the an­gel’ can be in­ter­pret­ed as a ha­lo.
  • The latest images from DLR's HRSC instrument show dark sand deposits near the south pole of Mars; the shape formed by the deposits is reminiscent of an angel with outstretched wings and a large heart under its right wing.
  • With a little imagination, the almost one-thousand-metre-high crater rim can even be interpreted as a halo.
  • HRSC has been mapping the Red Planet in unprecedented resolution, in three dimensions and in colour, since 2004 as part of ESA's Mars Express mission.
  • Focus: Space, planetary research, Mars

These images, recently acquired by DLR's High Resolution Stereo Camera (HRSC), show dune fields and several periglacial formations in the southern polar region of Mars. This is a factual description of the image content, but one might also see an angel and a large heart formed from the dark sands. It is just as if Earth’s neighbouring planet were getting ready for the holiday season.

HRSC has been mapping the Red Planet in unprecedented resolution, in three dimensions and in colour, since 2004 as part of ESA's Mars Express mission. HRSC was developed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and constructed in collaboration with partners in industry. HRSC is operated by the DLR Institute of Planetary Research. Mars Express provides new data on the geology, mineralogy and atmosphere of Mars, in order to gain insights into the climate history of Earth’s neighbouring planet and to clarify the role and location of water that is still present.

Summer at the south pole on Mars makes an angel and its heart visible

A 'seasonal angel' with a heart sends greetings from the Martian south pole. The dark angel and the heart, both consisting of volcanic sands, are located in the southern polar region of the planet, not far from the polar cap, at approximately 78 degrees south. Currently it is summer at this location. The permanent ice cap, consisting mostly of water ice and frozen carbon dioxide, now has a diameter of 400 kilometres and an average thickness of 1.5 kilometres. These are dimensions that are roughly comparable to the ice-covered island of Greenland on Earth. However, it is only this size in the southern summer. During the six-month winter, the south pole ice cap on Mars extends further, to almost 60 degrees south. Even in summer in the southern hemisphere of Mars, temperatures never rise above zero degrees Celsius. In winter, temperatures down to minus 133 degrees Celsius cause the carbon dioxide from the atmosphere to freeze and fall onto the ice cap as snow. This blanket of carbon dioxide ice is between one and two metres thick and sublimates again with the next spring, thus evaporating and re-exposing the landscape. Only on the permanent ice cap of the south pole does a thin layer remain. The atmosphere on Mars contains very little water vapour that can freeze to form ice. Water vapour forms only 0.02 percent of the planet's gas envelope, which consists mainly of carbon dioxide and nitrogen; on Earth, there is twenty times more water vapour in the atmosphere, averaging a concentration of 0.4 percent. Therefore, the angel and the heart are only visible in the southern summer; in winter they lie hidden under the layer of frozen carbon dioxide.

The angel's head – an impact crater

In the upper centre of the images, an impact crater approximately 15 kilometres across can be seen, in which dark sands form the 'angel's head’. With a little imagination, the almost one-thousand-metre-high crater rim can even be interpreted as a halo. In several places, the layered deposits of the polar cap, consisting of ice mixed with dust, are clearly visible on the upper slopes. Even in the oval depression that forms the 'angel's hand', the view of the layered polar deposits is unobstructed.

The southern part of the image (on the right in images 1,4 and 6 ) is also covered by stratified deposits. These consist of ice and dust as well, but they are much more finely layered, thinner and cover the south polar deposits. This type of deposit covers large parts of the high latitudes of Mars (approximately between 40 and 80 degrees north and south respectively), which is why it is referred to as a 'latitude-dependent mantle'. In many places, degradation phenomena due to erosion and sublimation of the ice in spring and summer are visible in the mantle, which has created several small geological windows in which the finer layer structure can also be seen on close inspection.

In the centre of the image, beneath the angel's outstretched wing, is a large, heart-shaped depression bounded by a scarp leading to another large dark dune field. The dark material, consisting of olivine and pyroxene minerals, may have come from deeper layers of deposited volcanic eruptive material or could have been blown into the depression. In the latter case, the edges of the terrain would have acted as windbreaks, causing the sands to slow down and be 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 images, numerous dark, intersecting lines can be seen on a very flat and bright surface. These are dust devil tracks, meaning traces left by numerous aeolian forces, caused by atmospheric turbulence. They leave these dark tracks on their path by 'sucking up' the lighter surface dust.

All images in high resolution and more images acquired by the HRSC instrument can be found in the Mars Express image gallery on flickr.

  • Image processing

    These images were acquired by the High Resolution Stereo Camera (HRSC) on 8 November 2020 during Mars Express orbit 21,305. The resolution is approximately 15 metres per pixel. The centre of the images is located at approximately 148 degrees east and 78 degrees south. The perpendicular colour view was generated using data acquired by the nadir channel, the field of view which is aligned perpendicular to the surface of Mars, and the colour channels of HRSC. The oblique perspective view was computed using a Digital Terrain Model (DTM) and data acquired by the nadir and colour channels of HRSC. The anaglyph, which provides a three dimensional view of the landscape when viewed using red-green or red-blue glasses, was derived from data acquired by the nadir channel and the stereo channels. The colour-coded topographic view 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 a Mars equipotential surface (Areoid).

    HRSC was developed and is operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). The systematic processing of the camera data was performed at the DLR Institute of Planetary Research in Berlin-Adlershof. Personnel in the Department of Planetary Sciences and Remote Sensing at Freie Universität Berlin used these data to create the image products shown here.

  • The HRSC experiment on Mars Express
    The High Resolution Stereo Camera (HRSC) was developed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and built in collaboration with partners in industry (EADS Astrium, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). The science team, which is headed by Principal Investigator (PI) Ralf Jaumann, consists of 52 co-investigators from 34 institutions in 11 countries. The camera is operated by the DLR Institute of Planetary Research in Berlin-Adlershof.
Contact
  • Elke Heinemann
    Ger­man Aerospace Cen­ter (DLR)
    Pub­lic Af­fairs and Com­mu­ni­ca­tions
    Telephone: +49 2203 601-2867
    Fax: +49 2203 601-3249

    Contact
  • Ulrich Köhler
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Rutherfordstraße 2
    12489 Berlin
    Contact
  • Daniela Tirsch
    Ger­man Aerospace Cen­ter (DLR)

    In­sti­tute of Plan­e­tary Re­search
    Telephone: +49 30 67055-488
    Fax: +49 30 67055-402
    Linder Höhe
    51147 Köln
    Contact
  • Prof.Dr. Ralf Jaumann
    Freie Uni­ver­sität Berlin
    In­sti­tute of Ge­o­log­i­cal Sci­ences
    Plan­e­tary Sci­ences and Re­mote Sens­ing
    Telephone: +49-172-2355864
    Malteserstr. 74-100
    12249 Berlin
    Contact

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