Mars Global Surveyor
Mars Orbiter Camera
Valley Network in Terra Tyrrhena
MGS MOC Release No. MOC2-155, 19 July 1999
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Small valleys in the martian cratered highlands are often quite old
and have been modified by erosion and wind action. They are thought to
have been formed by water. MOC images obtained over the past two
years suggest that most of these formed by sapping and flow of
groundwater. However, the possibility that the oldest valleys required
rainfall cannot be ruled out, because the valleys are so old and
modified. The lack of tiny tributary valleys on the upland surrounding
the big valley shown here suggests that rainfall played no role in
this particular case. This valley and its tributaries are located on
the rim of a crater at 16.8°S, 295.3°W in Terra Tyrrhena.
The fluids that once flowed in this valley would have moved from
the top toward the bottom of the image.
The small ridges on the floor of the valley are windblown sand dunes.
Illumination is from the left in this April 1999 picture.
Malin Space Science Systems and the California Institute of Technology
built the MOC using spare hardware from the Mars Observer mission. MSSS
operates the camera from its facilities in San Diego, CA. The Jet Propulsion
Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor
spacecraft with its industrial partner, Lockheed Martin Astronautics, from
facilities in Pasadena, CA and Denver, CO.
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