Mars Global Surveyor
Mars Orbiter Camera

Valley Network in Terra Tyrrhena

MGS MOC Release No. MOC2-155, 19 July 1999


997 KByte gif -- 356 KByte gif


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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