[meteorite-list] Mars Express Images: Crater Holden and Uzboi Vallis

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon May 9 15:24:12 2005
Message-ID: <200505091923.j49JNdM15777_at_zagami.jpl.nasa.gov>

http://www.esa.int/SPECIALS/Mars_Express/SEM9YX2IU7E_0.html

Crater Holden and Uzboi Vallis
European Space Agency
Mars Express
9 May 2005

These images, taken by the High Resolution Stereo Camera (HRSC) on board
ESA's Mars Express spacecraft, show the outlet channel of the Uzboi
Vallis system into Crater Holden on Mars.
 
 

Map showing crater and valley in context

The HRSC obtained these images during orbit 511 with a ground resolution
of approximately 45 metres per pixel. The scenes show the region of
Noachis Terra, over an area centred at about 26? South and 325? East.

The valley of Uzboi Vallis begins in the region of Argyre Planitia and
crosses the southern highlands in the direction of the northern
lowlands. It connects several large impact craters, such as the 140
kilometre-wide Crater Holden seen in the main image.

 
 
Black and white image of Crater Holden and Uzboi Vallis

Due to a layer of haze close to the base of Holden, the area within the
crater appears lighter coloured and slightly less detailed than the
surrounding area.

A small, dark dune-field can be seen in the eastern half of the crater
floor. It indicates the role of wind in the morphological evolution of
Crater Holden.

 
 
3D image of Crater Holden and Uzboi Vallis

The terrain within Crater Holden is the result of a long and varied
evolution. The numerous smaller craters inside Holden indicate that the
crater is old.

Many smaller craters on the floor of Holden are covered with sediments,
which were deposited after the formation of these craters and indicate
that they are older than the unfilled small craters.

The central mount of Holden is partly hidden, because it has also been
covered by sediments. The rim of the crater has been cut by gullies,
which sometimes form small valley networks.

 
 
Alluvial fan in Crater Holden

In the southern part of Crater Holden, well-preserved "alluvial fans"
(fan-shaped deposits of water-transported material) are visible at the
end of some gullies (see close-up left).

In other parts of the crater rim, the alluvial fans are less distinct
and partly covered by younger "talus cones" (cone-shaped piles of debris
from rock falls at the base of slopes).

 
 
Landslide blocks channel

Uzboi Vallis enters Crater Holden from the south-west. Two distinct
phases of its development can be seen. In the first phase, a valley was
formed up to 20 kilometres wide.

Later, a smaller channel was cut into the valley floor. The end of the
small channel has been blocked by a landslide from the crater rim (see
close-up 2).

 
 
Perspective view across Crater Holden, looking west

The deepest parts of the valley floor are more than 1600 metres below
the surrounding area. The numerous valleys at the flanks of Uzboi Vallis
indicate that water probably played a major role in the formation and
evolution of this region. Most of the valleys have been covered by
younger sediments, indicating they have been inactive in recent
geological time.
 
 
Perspective view of Crater Holden and Uzboi Vallis, looking south
 
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.
Image resolution has been decreased for use on the internet.
Received on Mon 09 May 2005 03:23:38 PM PDT