Mars Global Surveyor
Mars Orbiter Camera

Martian North Polar Cap on September 12, 1998

Mars Orbiter Camera Turned Off as Global Surveyor Completes One Year in Orbit and Resumes Aerobraking


 Mars Orbiter Camera Update: 19 September 1998

The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was powered off shortly after 3 PM PDT Sunday, September 13, 1998. The camera had been on since early June 1998 while acquiring images of the northern hemisphere of Mars. The camera will remain off until March 1999, when the MGS spacecraft will reach the circular, polar orbit from which the originally planned science observations will be obtained. To achieve this orbit, MGS will soon resume skimming through the upper atmosphere of Mars to slowly reduce the size of its orbit.

Imaging activities were ended at this time in order to lessen the Jet Propulsion Laboratory's Mars Surveyor Operations Project (MSOP) workload. MSOP, and its industrial partner Lockheed Martin Astronautics, become responsible for operating two additional spacecraft within the next few months: the Mars Climate Orbiter (scheduled for launch in December 1998) and the Mars Polar Lander (to be launched in January 1999). To acquire images, the MGS spacecraft must follow a specific pointing path after each aerobraking pass through the atmosphere, before reestablishing contact with Earth. This "rollout maneuver" requires the spacecraft team to determine if the power and thermal conditions on-board the spacecraft permit such maneuvers.

During the past year, MOC has acquired about two thousand images, roughly half of which have been high resolution views (2-20 meters, or 7-66 feet, per pixel) used for geological studies, and the other half low resolution views (several kilometers--or miles--per pixel) used to study the atmosphere. With the end of data acquisition, MOC team efforts now turn to processing and collating the images. Archiving plans call for materials collected late last year to be transferred to the Planetary Data System (PDS), which acts to conserve the original data and allow public access to them, within the next few months. All data collected during the first year of operations will be deposited with the PDS by mid-March 1999.

Among the highlights of the past year's observations are the occurrence of thousands of meters of layered materials in the walls of the Valles Marineris, evidence of sustained flow within some reaches of Martian valley systems, suspected evidence of seepage and ponding, and the discovery of dunes of a variety of shapes and brightnesses that suggest different compositions and particle sizes or shapes. These and other aspects of martian geology and meteorology can be seen in the sixty-seven WWW pages devoted to MOC images posted over the past year (

With the suspension of active imaging, weekly additions to the MOC WWW image site will also be suspended. Until mapping activities begin, results will instead be posted primarily as new science findings are presented by the MGS MOC team. In the coming months, papers discussing MOC results will be presented at the American Astronomical Society's Division of Planetary Sciences Annual Meeting (mid-October 1998), the Geological Society of America Annual Meeting (late-October 1998), and the American Geophysical Union Fall Meeting (early-December 1998).

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, CA. 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, CA and Denver, CO.

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