23. February 2022
Mission Mars Express

Blown by the wind – the Medusae Fos­sae For­ma­tion on Mars

Landscape shaped by the wind in Eumenides Dorsum
Land­scape shaped by the wind in Eu­menides Dor­sum
Image 1/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Landscape shaped by the wind in Eumenides Dorsum

Since Jan­uary 2004, the High Res­o­lu­tion Stereo Cam­era (HRSC) op­er­at­ed by the DLR In­sti­tute of Plan­e­tary Re­search on board ESA's Mars Ex­press or­biter has been map­ping Mars in high res­o­lu­tion, in colour and in '3D'. In the im­ages, gen­er­at­ed us­ing da­ta ac­quired on 14 May 2021 dur­ing or­bit 21,948, have a res­o­lu­tion of ap­prox­i­mate­ly 19 me­tres per pix­el. The land­scape is char­ac­terised by long-term wind ero­sion. In the cen­tre of the im­age, nu­mer­ous par­al­lel ridges and troughs, known as yardan­gs and wind gul­lies, can be seen. Nu­mer­ous 'blowouts' – saucer- or trough-shaped de­pres­sions cre­at­ed by wind ero­sion of pre-ex­ist­ing sand de­posits – can be seen in the area to the right of the im­age. North is on the right of the im­age. The size of the area in the im­age is ap­prox­i­mate­ly 180 by 80 kilo­me­tres.
Oblique perspective view of a landscape near Eumenides Dorsum
Oblique per­spec­tive view of a land­scape near Eu­menides Dor­sum
Image 2/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Oblique perspective view of a landscape near Eumenides Dorsum

Dig­i­tal ter­rain mod­els gen­er­at­ed us­ing da­ta ac­quired by the stereo im­age chan­nels of the HRSC cam­era sys­tem on ESA's Mars Ex­press or­biter can be used to cre­ate per­spec­tive views of the Mar­tian land­scape. This im­age shows a view of a land­scape near the Eu­menides Dor­sum moun­tain range, part of the Medusae Fos­sae For­ma­tion. Here, the wind has act­ed on an eas­i­ly erodi­ble sur­face for a long time. This has cre­at­ed 'yardan­gs' and wind gul­lies – ridges and troughs 'carved out' by the wind – as well as 'blowouts' – de­pres­sions with an ac­cu­mu­la­tion of sand in the shape of a cres­cent – which al­low con­clu­sions to be drawn about the pre­vail­ing wind di­rec­tion.
Oblique perspective view of a landscape near Eumenides Dorsum
Oblique per­spec­tive view of a land­scape near Eu­menides Dor­sum
Image 3/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Oblique perspective view of a landscape near Eumenides Dorsum

This per­spec­tive view shows a land­scape near the Eu­menides Dor­sum moun­tain range. It is part of the Medusae Fos­sae For­ma­tion (MFF), which ex­tends along the high­land-low­land bound­ary be­tween the vol­canic cen­tres of Thar­sis and Ely­si­um. This re­gion con­sists to a large ex­tent of eas­i­ly erodi­ble ma­te­ri­al. The wind has left its mark here in the form of 'yardan­gs' and wind gul­lies, which are par­al­lel nar­row ridges and troughs. They were cre­at­ed by grains of sand car­ried by the wind, which 'carved' these shapes out of the rock as if us­ing a sand­blaster.
The Eumenides Dorsum mountain range
The Eu­menides Dor­sum moun­tain range
Image 4/6, Credit: NASA/JPL (MOLA); FU Berlin

The Eumenides Dorsum mountain range

The Eu­menides Dor­sum moun­tain range is part of the Medusae Fos­sae For­ma­tion (MFF). This ex­tends over 5000 kilo­me­tres be­tween the vol­canic cen­tres around Thar­sis and Ely­si­um along the high­land-low­land (di­choto­my) bound­ary on the Mar­tian equa­tor. Al­most the en­tire area con­sists of eas­i­ly erodi­ble ma­te­ri­al. The DLR-op­er­at­ed HRSC stereo cam­era on ESA’s Mars Ex­press or­biter ac­quired im­ages of the land­scape on 14 May 2021 dur­ing or­bit 21,948, with the cen­tre of the im­age at ap­prox­i­mate­ly 192 de­grees east and 2 de­grees north. The land­scape shown in the im­ages pre­sent­ed here lies with­in the small­er white rect­an­gle. The large rect­an­gle marks the en­tire im­age strip ac­quired by HRSC dur­ing this or­bit.
The topography of the Eumenides Dorsum region
The to­pog­ra­phy of the Eu­menides Dor­sum re­gion
Image 5/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The topography of the Eumenides Dorsum region

The DLR High Res­o­lu­tion Stereo Cam­era (HRSC) on ESA's Mars Ex­press or­biter ac­quires im­ages of the Mar­tian sur­face at dif­fer­ent an­gles and with four colour chan­nels us­ing its nine sen­sors, which are ar­ranged across the line of flight. From the four stereo chan­nels look­ing at an an­gle and the nadir chan­nel point­ing per­pen­dic­u­lar­ly at Mars, teams of sci­en­tists at the DLR In­sti­tute of Plan­e­tary Re­search and Freie Uni­ver­sität Berlin com­pute dig­i­tal ter­rain mod­els that as­sign el­e­va­tion in­for­ma­tion to each pix­el. The colour scale at the top right of the im­age shows the dif­fer­ences in al­ti­tude in the re­gion. The flat moun­tain peaks in the south and east (north is on the right of the im­age) rise be­tween 1500 and 2000 me­tres above the turquoise de­pres­sions in the west at the top of the im­age. Be­tween the el­e­va­tions of the moun­tain range of Eu­menides Dor­sum, one can see the low­er-ly­ing area with its yardan­gs, wind gul­lies and blowouts, which were cre­at­ed by long-term wind ero­sion.
3D view of the landscape in Eumenides Dorsum
3D view of the land­scape in Eu­menides Dor­sum
Image 6/6, Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

3D view of the landscape in Eumenides Dorsum

Anaglyph im­ages can be gen­er­at­ed us­ing da­ta ac­quired by the nadir chan­nel of the DLR-op­er­at­ed HRSC cam­era sys­tem on ESA's Mars Ex­press or­biter, which is di­rect­ed per­pen­dic­u­lar­ly to the sur­face of Mars, and one of the four oblique stereo chan­nels. When used with red-blue or red-green glass­es, they pro­vide a three-di­men­sion­al view of the land­scape. North is to the right in this im­age. The to­pog­ra­phy of the land­scape, which is strong­ly in­flu­enced by the wind, is clear­ly vis­i­ble. In the north, on the right of the im­age, nu­mer­ous 'blowouts' can be seen. These are round­ed de­pres­sions with a cres­cent-shaped ac­cu­mu­la­tion of sand around them. The left half of the im­age is char­ac­terised by nu­mer­ous par­al­lel troughs that have been 'carved out' by the wind as if us­ing a sand­blaster.
  • Images from DLR's High Resolution Stereo Camera show a landscape around the mountain range Eumenides Dorsum in the Medusae Fossae region, which is strongly influenced by the wind. Wind has been the most significant force reshaping the surface of the Red Planet for two billion years.
  • For 19 years, the DLR-developed stereo camera HRSC on board ESA's Mars Express mission has been mapping Mars in high-resolution, colour and in 3D.
  • Focus: Space exploration, Solar System exploration, Mars

These images, created using data acquired by the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express orbiter, show a landscape formed as a result of intense wind erosion. It is located on the Eumenides Dorsum mountains, a north-south oriented mountain range on Mars. This is an impressive example of the erosive effects of wind on Mars, which has been the most significant force involved in reshaping the surface of the Red Planet for two billion years.

HRSC was developed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and is operated by its Institute of Planetary Research in Berlin-Adlershof. Since 2004, it has been mapping Mars in high resolution, in three dimensions and in colour. The data acquired by HRSC are an important resource for current and future Mars research. The findings already obtained in the course of the mission have greatly changed researcher's theories about the geological evolution of the Red Planet.

The Medusa Fossae on the 'back' of the goddesses of vengeance

The Eumenides Dorsum mountain range is named after the vengeful goddesses in Greek mythology, the Eumenides – also known as the Furies – and is part of the Medusae Fossae Formation (MFF). This extends over 5000 kilometres between the volcanic centres around Tharsis and Elysium, along the highland-lowland boundary (Martian dichotomy), and has a surface area comparable in size to India. The word fossae, Latin for trenches, indicates that tectonic processes also played a role in shaping the landscape here. The rigid crust was stretched by rising magma bubbles. In the process, it broke open, giving rise to the formation of numerous tectonic grabens.

The MFF seems to consist of easily erodible materials. These are probably pyroclastic flows that originated from the volcanoes of the Tharsis region or Olympus Mons approximately 3.8 to 3 billion years ago (in the Hesperian period). These deposits are formed when red-hot rock fragments ejected by volcanoes are bonded together in a mixture of hot gases and ash to form more or less solidified rock such as tuff and pumice. However, these volcanic deposits do not have a high density and are therefore relatively prone to erosion.

Yardangs and blowouts – evidence of long-term wind erosion

In general, the surface features of the formation in this area of about 180 by 80 kilometres are smooth and gently undulated, as can be seen in the upper left part of images 1, 5 and 6 . In other regions, the wind has formed narrow ridges and troughs, sometimes kilometres long, running parallel to each other. The narrow ridges are known as yardangs and have been carved out of the rock by the grains of sand carried by the wind, as if someone had used a sandblaster. If the wind blows in the same direction over a longer period of time, the elongated troughs can also form wind gullies, in which the wind is accelerated as if by nozzles, ultimately intensifying the erosion process. Yardangs are clearly visible as small, streamlined ridges in the upper centre of the oblique perspective images and in the lower left part of images 1, 5 and 6. These structures bear a strong resemblance to desert features in Central Asia, where they were first described in in 1902 in the Lop Nor desert by the Swedish explorer Sven Hedin after his expedition. The Uyghur word for these landforms has thereby become part of the scientific terminology.

Dozens of crescent-shaped ridges can be seen, each with a central depression, can be seen in the lower right of the vertical plan views. These depressions, which appear to have been excavated by the wind, are referred to as 'blowouts'. A blowout is a saucer- or trough-shaped depression created by wind erosion of a pre-existing sand deposit and formed together with an adjoining sand accumulation referred to as a depositional lobe or blowout dune. Their formation process is relatively simple – wind transports sand, eroding the soft surface. When this hits a buried object, such as a rock or simply a somewhat resistant sedimentary deposit, the wind is forced to blow around it. This creates a vortex at the front of the obstacle. The wind is then driven downwards, around the obstacle and then upwards again, creating a depression as the sand is lifted from the base of the obstacle and deposited behind it.

Only a few craters are found in this area. This is an indication that wind erosion was the most recent change process after the deposition of MFF to have affected the surface here. In the upper right of the perpendicular images, some impact craters can be seen, revealing the underlying older rocks that were covered by the MFF. The MFF is thought to be the largest sediment deposit on the planet as well as the largest single source of dust on Mars.

Image processing

These images were created using data acquired by the High Resolution Stereo Camera (HRSC) on 14 May 2021 during orbits 21,948 of the Mars Express spacecraft. The image resolution is approximately 19 metres per pixel. The centre of the image is located at approximately 192 degrees east and 2 degrees north. 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 views were computed using a Digital Terrain Model (DTM) and data acquired by the nadir and colour channels of HRSC. The colour-coded topographic view is based on a DTM of the region from which the topography of the landscape can be derived. The reference body for the HRSC DTM is a Martian equipotential surface (areoid).

The HRSC was developed and is operated at the German Aerospace Center (DLR) in cooperation with German industry. 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 (Airbus, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). The science team, which is headed by Principal Investigator (PI) Thomas Roatsch, consists of 50 co-investigators from 34 institutions in 11 countries.

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

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  • Ulrich Köhler
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
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  • Thomas Roatsch
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Rutherfordstraße 2
    12489 Berlin
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