NASA Mars Picture of the Day: Defrosting Patterns 09-18-2003

Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-487, 18 September 2003

NASA/JPL/Malin Space Science Systems

This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
picture shows patterns created by defrosting processes on the
south polar seasonal ice cap. Seasonal cap refers to the part of
the polar cap that comes and goes with the seasons, as opposed to
the residual cap, which lasts throughout the summer. The area shown
here, in summer, will have no frost. This picture was taken during
southern spring. As the seasonal frost begins to sublime away,
dark cracks form a polygon pattern, and wind blows material to
form varied bright and dark streaks. What is unknown
is whether the dark streaks consist of sand and silt from beneath
the seasonal frost, or whether they, too, consist of frost that has
been transformed into coarse-grained particles that can be mobilized
by wind. Alternatively, the streaks represent erosion and removal
of frost, rather than deposition of granular material. The bright
streaks are most likely made of frost—whether they are water ice or
carbon dioxide ice remains to be determined. The bulk of the frosted
surface shown here is carbon dioxide ice. The image is located
near 87.3°S, 192.4°W. The picture covers an area 3 km
(1.9 mi) wide and 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.