NASA Mars Picture of the Day: Polygon/Cracked Sedimentary Rock

Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-930, 4 December 2004

NASA/JPL/Malin Space Science Systems

Exposures of sedimentary rock are quite common on the
surface of Mars. Less common, but found in many craters
in the regions north and northwest of the giant basin,
Hellas, are sedimentary rocks with distinct polygonal
cracks in them.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
image shows an example from the floor of an unnamed crater
near 21.0°S, 311.9°W. Such cracks might have
formed by desiccation as an ancient lake dried up, or
they might be related to ground ice freeze/thaw cycles
or some other stresses placed on the original sediment
or the rock after it became lithified. The 300 meter
scale bar is about 328 yards long. The scene is illuminated
by sunlight from the upper left.

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, California.
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,
California and Denver, Colorado.