Saturday, December 4, 2010

Geology of Tethys


Geologic faults among craters on Saturn's moon Tethys are depicted in this image captured during a flyby of the moon by NASA's Cassini spacecraft on August 14, 2010.

The brightly illuminated, prominent impact crater near the bottom middle of this image has been dissected by numerous parallel faults that run diagonally across the image. The presence of the faults that cut through the crater and the movement of surface materials have made the crater outline somewhat non-circular. Near the center of the image, running diagonally from the left to right, is an old graben, or linear depression of terrain between faults. See PIA07736 and PIA07734 for images showing geologic features on Tethys taken during an earlier flyby.

Below these faults and near the middle top of the image is a large ancient impact crater that is so highly overprinted by more recent craters that it can barely be recognized.

On the left of the image, there are some horizontal lines that can be seen very faintly cutting across craters. These lines are artifacts of missing data in the raw image that could not be eliminated through processing the image.

This view looks toward the leading hemisphere of Tethys (1062 kilometers, 660 miles across). The view is centered on terrain at 59 degrees North latitude, 79 degrees West longitude.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 40,000 kilometers (25,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 103 degrees. Image scale is 234 meters (767 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

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