Status Report

NASA Mars Picture of the Day: 4 Mars Years of Change

By SpaceRef Editor
May 23, 2005
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Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-1100, 23 May 2005

NASA/JPL/Malin Space Science Systems

These two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
images were acquired a little more than four Mars years
apart. One Mars year is about 687 Earth days long. The two
images show a portion of the south polar cap, which is composed
of frozen, layered, carbon dioxide. Each Mars year since MGS
has been observing the planet, the mesas and buttes composed
of carbon dioxide have gotten a little bit smaller, and the
pits and holes have become a little bit wider. The scarps
formed in frozen carbon dioxide in the south polar region
are retreating at an average rate of about 3 meters per
Mars year. The example shown here includes an image obtained
in August 1999, and a more recent picture from April 2005.
Arrow “1” points to a dramatic example of the changes that
have occurred; in this case a mesa shrank to a small butte in
just four martian years. Arrow “2” indicates pits that developed
in the cap layer of a carbon dioxide mesa that eroded
during the same interval. Acquired during early southern
spring, both images are 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.

SpaceRef staff editor.