MGS MOC Release No. MOC2-264, 4 December 2000
Color Composite of subframes of MOC
images M01-00824 and M01-05269
Subframe of MOC
Subframe of MOC image M19-00309
Located in Pollack Crater, a 95 km- (59 mi-) wide impact basin at 7.9°S, 334.7°W, White Rock is the light-red/orange feature with the rectangular white box drawn on it in the context view (Picture A) above. The white box indicates the location of a sub-frame of a MGS Mars Orbiter Camera (MOC) image acquired in September 2000, shown in Picture B. The light-toned material that gives White Rock its name forms steep cliffs with valleys between them covered by dark, windblown, rippled sand. Picture C shows a close-up of a portion of Picture B, illustrating that the bright material is layered (arrow, "layers") and that there is an old impact crater (arrow, "crater") that has been partly uncovered from beneath the White Rock material.
The layering in White Rock suggests that the material is sediment deposited at some time in the distant past within Pollack Crater. The fact that the material erodes to form steep cliffs suggests that it is hard like rock. Thus, White Rock is interpreted to be an outcrop of sedimentary rock. It is probably a small remnant of a larger body of rock that may have once covered the entire floor of Pollack Crater; this view is supported by the observation that more extensive layered rocks are seen in other craters across the surface of the red planet (e.g., the crater at 8°N, 7°W).
All three pictures shown here are illuminated by sunlight from the upper left, north is up. Pollack Crater was named in 1997 for James B. Pollack (1938-1994), a NASA Ames Research Center scientist known in the Mars research community for his atmospheric research with Mariner 9 and Viking data and the development of key computer models used to investigate the red planet's winds, storms, and climate.
(A) Pollack Context:
(C) Layers and Partly-Exhumed Crater:
(D) MOC Narrow Angle Views of "White Rock" from the MSSS MOC Gallery:
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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