8. September 2016

Was there an ocean on Mars?

View of the frac­ture sys­tem in the Utopia Plani­tia im­pact basin
Image 1/5, Credit: ESA/DLR/FU Berlin - CC BY-SA 3.0 IGO.

View of the fracture system in the Utopia Planitia impact basin

This colour im­age was cre­at­ed from the nadir chan­nel ori­ent­ed per­pen­dic­u­lar to the sur­face of Mars and the colour chan­nels of the HRSC. It shows a net­work of huge frac­tures in Utopia Plani­tia. New re­search re­sults link the for­ma­tion of these huge ‘poly­gons’ in this re­gion to the pre­vi­ous ex­is­tence of an ocean in the Mar­tian North­ern Low­lands. Some of the graben show dark de­posits stretch­ing along their up­per edges. It is con­ceiv­able that these are dark, fine-grained ash lay­ers emerg­ing. They are the source of the widespread black sand dunes on Mars.
Per­spec­tive view of the frac­ture sys­tem in Utopia Plani­tia
Image 2/5, Credit: ESA/DLR/FU Berlin - CC BY-SA 3.0 IGO.

Perspective view of the fracture system in Utopia Planitia

This per­spec­tive an­gle view was cal­cu­lat­ed by the stereo chan­nels of the High Res­o­lu­tion Stereo Cam­era op­er­at­ed by the Ger­man Aerospace Cen­ter on board the Eu­ro­pean Mars Ex­press space­craft. A net­work of huge frac­tures cov­ers the buried im­pact basin of Utopia Plani­tia. It mea­sures 2000 kilo­me­tres in di­am­e­ter and is lo­cat­ed in the Mar­tian North­ern Low­lands. These sur­face struc­tures, re­ferred to as poly­gons, would sug­gest that an ocean once ex­ist­ed here.
Anaglyph im­age of a part of the Utopia Plani­tia re­gion
Image 3/5, Credit: ESA/DLR/FU Berlin - CC BY-SA 3.0 IGO.

Anaglyph image of a part of the Utopia Planitia region

Anaglyph im­ages can be cre­at­ed from the nadir chan­nel of the HRSC cam­era sys­tem op­er­at­ed by DLR on board the ESA Mars Ex­press space­craft, which is di­rect­ed ver­ti­cal­ly on­to the sur­face of Mars, and the oblique view from one of the four stereo chan­nels. When us­ing red-blue or red-green glass­es, they pro­vide a re­al­is­tic, three-di­men­sion­al view of the land­scape. The labyrinth-like sys­tem of frac­tures that can be seen on the im­ages con­sists of graben up to two kilo­me­tres wide that run back and forth and form poly­gon-shaped struc­tures be­tween five and 20 kilo­me­tres in di­am­e­ter.
To­po­graph­ic im­age map of a part of the Utopia Plani­tia re­gion
Image 4/5, Credit: ESA/DLR/FU Berlin - CC BY-SA 3.0 IGO.

Topographic image map of a part of the Utopia Planitia region

Dig­i­tal ter­rain mod­els of the Mar­tian sur­face can be de­rived from da­ta ac­quired by the nadir chan­nel, which is di­rect­ed ver­ti­cal­ly on­to the Mar­tian sur­face, and the stereo chan­nels of the High Res­o­lu­tion Stereo Cam­era (HRSC) on Mars Ex­press. In this colour-cod­ed im­age, the ab­so­lute el­e­va­tions above a ref­er­ence lev­el, the aeroid (de­rived from Ares, the Greek name for Mars), are de­pict­ed. These el­e­va­tion val­ues can be read based on the colour key at the top right of the im­age.
To­po­graph­i­cal con­text map of a part of the Utopia Plani­tia re­gion
Image 5/5, Credit: NASA/JPL/USGS (MOLA); FU Berlin.

Topographical context map of a part of the Utopia Planitia region

The im­ages were ac­quired by the High Res­o­lu­tion Stereo Cam­era (HRSC) dur­ing Mars Ex­press Or­bit 15,804 on 21 June 2016. The im­age res­o­lu­tion is 15 me­tres per pix­el. The cen­tre of the im­age is lo­cat­ed at 101 de­grees east and 39 de­grees north. The net­work of huge frac­tures in the Utopia Plani­tia re­gion is linked to the past ex­is­tence of an ocean in the North­ern Low­lands of Mars.

A network of huge fractures covers Utopia Planitia – a buried impact basin measuring 2000 kilometres in the Martian Northern Lowlands, which was the destination of the United States Viking 2 lander in 1976. These surface structures, which are referred to as polygons, would suggest that there was once an ocean here.

The images shown here were acquired on 21 June 2016 by the High Resolution Stereo Camera (HRSC) operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) on board the European Mars Express spacecraft. The labyrinth-like fracture system seen on the images consists of graben up to two kilometres wide that run back and forth and form polygon-shaped structures between five and 20 kilometres in diameter.

Giant polygons, 'pancake-shaped' ejecta blankets and dark graben

New results link the formation of these huge polygons in the Utopia Planitia region to the former existence of an ocean in the Martian Northern Lowlands. It is conceivable that the polygons (Latin for 'many-sided structures') formed in fine-grained sediments covering a rough basement.

Fine-grained sediments such as mud, for example, are deposited in large bodies of water such as oceans. In the past, the surface – now covered by sediment – could have been just as uneven as the Southern Highlands of Mars. At a later point in time, the surface was subjected to tectonic processes. The polygons are similar in morphology and size to polygons on Earth, which form in fine-grained deposits in shallow seawater when the water is displaced.

Some impact craters can also be seen in the images. The shape of the ejecta blankets around the craters in this region can be described as pancake-like. This shape indicates that ice and/or water was present in the subsurface at the time of impact. This then melted or escaped upon impact and mixed with the material that was catapulted out, so that a muddy mass flowed out of the crater.

Some of the graben show dark deposits stretching along their upper edges. It is conceivable that these are emerging dark, fine-grained ash layers that are the source of the widespread black sand dunes on Mars. It is also striking that these dark lines occur mainly on the side of the slope facing the Sun. Scientists therefore assume that the emergence of the ash layers from below the cover layer of ice, debris and dust was facilitated by solar radiation. Accordingly, the ice sublimated on the heated slopes, thereby allowing the covering layer of debris and dust, which was no longer held in place, to slip off or be worn away. As a result, the ash layer appeared.

  • Image processing

    The images were acquired by the High Resolution Stereo Camera (HRSC) during Mars Express Orbit 15,804 on 21 June 2016. The image resolution is 15 metres per pixel. The centre of the image is at about 101 degrees east and 39 degrees north. The colour view was created from the nadir channel oriented perpendicular to the surface of Mars and the colour channels of the HRSC; the perspective angle view was calculated from the HRSC stereo channels. The anaglyph image, which conveys a three-dimensional impression of the landscape when viewed with red-blue or red-green glasses, was derived from the nadir channel and one stereo channel. The view, encoded in rainbow colours, is based on a digital terrain model of the region from which the topography of the landscape can be derived. The reference unit for the HRSC-DTM is a Martian globe.

  • The HRSC experiment

    The High Resolution Stereo Camera was developed at 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 over 40 co-investigators from 33 institutions and ten countries. The camera is operated by the DLR Institute of Planetary Research in Berlin-Adlershof. The images shown here were generated by the Institute of Geological Sciences at FU Berlin in conjunction with the DLR Institute of Planetary Research in Berlin.

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
  • 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
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