[meteorite-list] Charitum Montes: A Cratered Winter Wonderland (Mars Express)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 6 Dec 2012 13:52:51 -0800 (PST)
Message-ID: <201212062152.qB6LqpRu017594_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaCP/SEMH7W2ABAH_index_0.html

Charitum Montes: a cratered winter wonderland
European Space Agency
6 December 2012

[Image]
The high-resolution stereo camera on ESA's Mars Express imaged the
Charitum Montes region of the Red Planet on 18 June, near to Gale crater
and the Argyre basin featured in our October and November image releases.
 
The brighter features, giving the image an ethereal winter-like feel in
the colour images, are surfaces covered with seasonal carbon dioxide frost.

Charitum Montes are a large group of rugged mountains extending over
almost 1000 km and bounding the southernmost rim of the Argyre impact
basin.

They can be seen from Earth through larger telescope and were named by
Eugene Michel Antoniadi (1870-1944) in his 1929 work "La Planete Mars."
 
[Image]
Annotated Image
 
The images in this release all show the region's old and highly-sculpted
terrain, pockmarked with many large craters, all of which have been
substantially filled in. The whole region is dusted with brighter carbon
dioxide frost.

[Image]
Perspective view
 
Numerous smaller "pedestal craters" can also be seen in the 3D and 2D
images. These are impact craters where the ejecta have formed a higher
relief above the surroundings. One striking example is visible on the
smooth plain to the lower right in the annotated image (Box A).
 

[Image]
Topographic view
 
The ejecta surrounding pedestal craters form erosion-resistant layers,
meaning that the immediate vicinity around the crater erodes more slowly
than the surrounding terrain. The resistant ejecta layer is largely
untouched, forming the pedestal.
 
[Image]
Perspective view
 
Another well-preserved example of a pedestal feature surrounding an
impact crater can be seen within the large, old and heavily-degraded
crater on the lower-left side of the annotated image (Box B).

In the centre of the 2D images and dominating the perspective images is
a crater some 50 km wide filled with thick sedimentary deposits.

These deposits appear to have been introduced through one of several
breaches in the northern crater rim (Box C in the annotated image).

Dendritic channels appear to emanate from a completely filled-in crater
in this region (Box D), at the periphery of the large crater's northern
edge.

Within the large crater, near to where the breach (C) in the crater wall
occurred, though unconnected to this event, we can also see a small dune
field (Box E).

A region of significant interest to scientists lies within the large
crater towards the top left of the first image (Box F). This crater
shows a diverse range of filling material, with layers of varying colour
and texture.
 
[Image]
Charitum Montes in context
        

The uppermost layer appears to be bright and smooth, taking on the
appearance of a relatively thin blanket with some impact craters.

This layer interfaces with the underlying darker layer via some very
sharply defined edges, possibly as a result of erosion.

The underlying darker material has a much rougher and mottled
appearance, and planetary geologists are still studying possible causes.

To the left of the crater interior, another layer of sediments clearly
sets itself apart from the underlying strata, partly forming flat-topped
structures (Box G).
 
[Image]
3D view
 
The complexity and diversity of some areas in this winter wonderland
would doubtless give Father Christmas a hard time in finding somewhere
safe to land, but images like these are giving planetary geologists yet
another fascinating region of the Red Planet to study.
Received on Thu 06 Dec 2012 04:52:51 PM PST