16. Roter Kamm, Namibia
Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) radar image. Radar imaging can contribute significantly to the study of desert landforms, such as the Roter Kamm Crater (and the Aorounga Crater, slides #21 and #22), because radar waves can penetrate thin layers of dry sand to reveal details of geologic structure that are invisible to other sensors. Processing involved merging multiple radar images to generate the final colored image. Roter Kamm's rim appears as a radar-bright, circular feature located in the lower central portion of the image. Geophysical data indicate that the crater fill is several hundred meters thick. Conventional imagery could not detect the brightly colored surfaces immediately surrounding the crater, because they are covered by sand. The faint blue surfaces adjacent to the rim might indicate the presence of a layer of rocks ejected from the crater during the impact. The darkest areas are thick, windblown sand deposits that form dunes and sand sheets. The sand surface is smooth relative to the surrounding granite and limestone rock outcrops and appears dark in radar image. The green tones are related primarily to larger vegetation growing on sand soil, and the reddish tones are associated with thinly mantled limestone outcrops. The bright white, irregular feature in the lower right corner is a small hill of exposed rock outcrop.
courtesy of NASA/JPL.