Tuesday, August 14, 2012

Exposed Clasts in Gale Crater


This color image from NASA's Curiosity rover shows an area excavated by the blast of the Mars Science Laboratory's descent stage rocket engines. This is part of a larger, high-resolution color mosaic made from images obtained by Curiosity's Mast Camera.

With the loose debris blasted away by the rockets, details of the underlying materials are clearly seen. Of particular note is a well-defined, topmost layer that contains fragments of rock embedded in a matrix of finer material. Shown in the inset in the figure are pebbles up to 1.25 inches (about 3 centimeters) across (upper two arrows) and a larger clast 4 inches (11.5 centimeters) long protruding up by about 2 inches (10 centimeters) from the layer in which it is embedded. Clast-rich sedimentary layers can form in a number of ways. Their mechanisms of formation can be distinguished by the size, shape, surface textures and positioning with respect to each other of the fragments in the layers.

The images in this mosaic were acquired by the 34-millimeter Mastcam over about an hour of time on August 8, 2012 PDT (Aug. 9, 2012 EDT), each at 1,200 by 1,200 pixels in size.

In the main version, the colors portrayed are unmodified from those returned by the camera. The view is what a cell phone or camcorder would record since the Mastcam takes color pictures in the exact same manner that consumer cameras acquire color images. The second version (Figure 1), shows the colors modified as if the scene were transported to Earth and illuminated by terrestrial sunlight. This processing, called "white balancing," is useful for scientists to be able to recognize and distinguish rocks by color in more familiar lighting.

Photo credit: NASA/JPL-Caltech/MSSS

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