[meteorite-list] Mars Express Images: The Channels of Reull Valli

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Dec 9 13:51:29 2004
Message-ID: <200412091851.KAA11436_at_zagami.jpl.nasa.gov>

http://www.esa.int/export/SPECIALS/Mars_Express/SEM1EQWDE2E_0.html

The channels of Reull Vallis
European Space Agency
Mars Express
7 December 2004

These images, taken by the High Resolution Stereo Camera (HRSC) on board
ESA's Mars Express spacecraft, show a region of Reull Vallis in the
southern hemisphere of Mars.
 
 
Map showing Reull Vallis in context

The images show an area located at about latitude 42? South and
longitude 102? East. The image was taken with a ground resolution of
about 21 metres per pixel during Mars Express orbit 451 in May 2004.

Reull Vallis is an outflow channel that extends 1500 kilometres across
Promethei Terra in the direction of Hellas Basin. It is approximately 20
kilometres wide and has cut into the surrounding plain to a depth of
1800 metres. It is the major outflow channel in the region and exhibits
a high degree of surface modification, suggesting a complex evolution.

 
 

Reull Vallis in colour

In these images, Reull Vallis extends from the east to the north-west
and is connected to a tributary in the south (Teviot Vallis). Distinct
parallel structures are visible in the channels, possibly caused by
glacial flow of loose debris mixed with ice. Small depressions, located
on the flow features, are probably caused by the sublimation of ice.

Numerous impact craters, visible on the flanks of the valley, have been
filled with material from these flows. Distinct flow features can be
recognised within impact craters, for example, the 15-kilometre wide
crater in the west (bottom) of the image.

 
 

3D anaglyph of Reull Vallis
 
There is a clear morphological distinction between the heavily eroded
south-west and the plains of the north-east, which have experienced much
less erosion. While most landforms throughout the image have a rounded,
softened appearance, younger structures have a distinctly sharp and
raised morphology.
 
 

Reull Vallis detail 1

On the southern and western edges of the colour image, large impact
craters are visible. Their diameters range from 15 to 35 kilometres.
These craters have heavily eroded rims and are partly filled with
material. Erosion has left distinct, branched gully systems at the edge
of the large crater that is located on the southern edge of the image.
 
 

Perspective view of Reull Vallis, looking west
 
Image resolution has been decreased for use on the internet. The colour
images were processed using the HRSC nadir (vertical view) and three
colour channels. The perspective views were calculated from the digital
terrain model derived from the stereo channels.
 
 
The 3D anaglyph image was created from the nadir channel and one of the
stereo channels. Stereoscopic glasses are needed to view the 3D image.
Received on Thu 09 Dec 2004 01:51:24 PM PST