* Astronomy

Blobrana · L

RE: Aram Chaos

Blobrana · L

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express spacecraft, show Aram Chaos, 280-km-wide circular structure characterised by chaotic terrain.

The HRSC obtained these images during orbit 945 with a ground resolution of approximately 14 metres per pixel. The images show the region of Aram Chaos, at approximately 2° North and 340° East.

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Credit ESA

Aram Chaos is a 280-km-wide almost-circular structure located between the outflow channel Ares Vallis and Aureum Chaos. It is one of many regions located east of Valles Marineris and characterised by chaotic terrain.
As the name 'chaos' suggests, this terrain comprises large-scale remnant massifs, large relief masses that have been moved and weathered as a block. These are heavily eroded and dominate the circular morphology, or structure, which may have formed during an impact. As seen in the colour image, these remnant massifs range from a few kilometres to approximately ten kilometres wide and have a relative elevation of roughly 1000 metres.

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-- Edited by Blobrana at 00:33, 2006-06-06

Blobrana · L

Mars Global Surveyor Mars Orbiter Camera

This picture is a mosaic of two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of sedimentary rock outcrops in Aram Chaos, near Ares Vallis, Mars.
Aram Chaos is an impact crater that was nearly completely filled with material, some of which is light-toned, layered sedimentary rock.
The MGS Thermal Emission Spectrometer team detected crystalline hematite in Aram Chaos, attesting to its potential similarity to some of the rocks in Meridiani Planum, where the Mars Exploration Rover (MER-B), Opportunity, has been operating.

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During April 2005, an opportunity arose to acquire a MOC narrow angle camera image that would mosaic with a previous picture, (R11-02268).
The figure shown here is a mosaic of that earlier image, obtained in November 2003, and the newer picture, from April 2005. Sunlight illuminates the scene from the right, and north is toward the bottom.

A steep slope is seen near the top of the image. It formed in light-toned sedimentary rock, and it has shed debris to form a suite of darker-toned talus deposits.
These deposits are the products of dry mass movement; the darker tone of the debris might be an indication that the material is less weathered or coarse-grained.

Evident below the scarp are several light-toned yardangs, sculpted by wind.
Erosion of the yardang-forming material, interpreted to be sedimentary rock, has revealed dark-toned blocks, separated by troughs.
The blocks pre-date the deposition of the yardang-forming material.
The presence of these broken-up blocks suggests that a chaotic terrain pattern formed in Aram Chaos long ago, before subsequent deposition of material that later became the light-toned, sedimentary rock.
The geologic history recorded in Aram Chaos is no less complex than has been observed by MOC in other large craters, such as Gale.