Ares Vallis Cataract
NASA/JPL/UArizona
Ares Vallis Cataract
PSP_003538_1885  Science Theme: Fluvial Processes
This observation shows a dry cataract within Ares Vallis. A cataract is a large waterfall where there is a high, steep drop. The presence of this large cataract in Ares Vallis confirms that this channel was carved by water, probably in one or many large catastrophic flooding events.

This feature has many of the same characteristics as the cataracts on Earth associated with the flood that carved the Channelled Scablands in Washington state, including horseshoe-shaped headcuts and longitudinal grooves. These grooves in the lower portion of the image lead up to the cataract, with the water flowing from the south to the north in this image. It then flowed down the cataract into the smaller incised channel.

The horseshoe-shaped headcut here is only part of a larger cataract system, and probably formed during the last stage of flooding. The inner channels are now filled with dunes formed by wind blowing along the channel floor.



Written by: Alexandra Davatzes  (16 May 2007)

This is a stereo pair with PSP_004171_1885.
 
Acquisition date
29 April 2007

Local Mars time
15:28

Latitude (centered)
8.380°

Longitude (East)
335.605°

Spacecraft altitude
275.9 km (171.5 miles)

Original image scale range
27.6 cm/pixel (with 1 x 1 binning) so objects ~83 cm across are resolved

Map projected scale
25 cm/pixel and North is up

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Equirectangular

Emission angle
1.2°

Phase angle
57.0°

Solar incidence angle
58°, with the Sun about 32° above the horizon

Solar longitude
228.1°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  337.5°
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POSTSCRIPT
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.