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Mars Global Surveyor
Mars Orbiter Camera

Mars Orbiter Camera (MOC) High Resolution Images:
Springtime Close-up of the Permanent South Polar Ice Cap


Mars Global Surveyor Mars Orbiter Camera Release:          MOC2-36A, -36B, -36C, -36D
Mars Global Surveyor Mars Orbiter Camera Image ID:         567897744.7709
(A) fig6a_cntxA_ICON.gif

222z (A) Color mosaic of Viking Orbiter images from NASA's "Planetary Photojournal". The bright feature is the permanent south polar ice cap, it is about 400 km (249 miles) across from left to right. The outline of (B) is shown as a box. Sun illumination is from top.

(B) fig6a_cntxB_ICON.gif

(B) Portion of Viking Orbiter 2 image 421B74, reproduced here at full resolution of about 174 meters (568 feet) per picture element. The outlines of (C) and (D) are shown as black boxes. North is up, sun illumination is from the upper right.

(C) fig6a_cntxC_ICON.gif

(C) Highest-resolution pre-Mars Global Surveyor view. Image is a portion of Mariner 9 DAS #7900063. It is shown here at full spatial resolution of about 100 meters (327 feet) per pixel. Box indicates location of MOC image (D). North is toward the upper right (compare with (B)), sun illumination is from the left.

(D) fig6a_7709_ICON.gif

(D) Subframe of MOC image 7709 reproduced at full resolution, about 50 meters/pixel (164 feet/pixel). Picture shows an area approximately 30 x 29 km (18.6 x 18.0 miles) in size. Sun illumination is from the lower right.

You may need to adjust the images for the gamma of your monitor to insure proper viewing.

Note: This MOC image is made available in order to share with the public the excitement of new discoveries being made via the Mars Global Surveyor spacecraft. The image may be reproduced only if the image is credited to "Malin Space Science Systems/NASA". Release of this image does not constitute a release of scientific data. The image and its caption should not be referenced in the scientific literature. Full data releases to the scientific community are scheduled by the Mars Global Surveyor Project and NASA Planetary Data System. Typically, data will be released after a 6 month calibration and validation period.

Click Here for more information on MGS data release and archiving plans.


Textures on the surface of the permanent south polar ice cap are visible in this MOC image taken in late southern spring. The Mariner 9 (C) and Viking (A & B) images show what this area would look like in summer--the large diagonal lineation that has a curved "hook" at the lower right of the MOC subframe is defrosted in the summertime views from Viking and Mariner 9. The MOC frame, however, was taken at a time when it was still cold enough that the region, including this lineation, is covered with ice and snow. The south polar cap on Mars is known from previous study to contain a mixture of water ice, frozen carbon dioxide ("dry ice") and dust. Typical temperatures here are as low as -125°C (-193°F) or more.

The rough and pitted textures on this portion of the polar cap are probably caused by a combination of factors: (a) the removal of ice in the spring and summer seasons, (b) wind erosion, and (c) removal and/or erosion of ice and dust over long time periods (millions of years). When the ice cap warms in spring and summer, it does not melt. Instead, the ice (water and carbon dioxide) changes directly from solid to gas without melting (i.e., without creating liquid), a process called sublimation. Frozen carbon dioxide ("dry ice") behaves like this at room temperature on Earth--on Mars, water also behaves this way because the present atmosphere so thin. Some of the textures created by the sublimation of the polar cap include surprising circular mesas that resemble giant medicinal pills (see center right of the MOC image!).

The MOC picture is a subframe of image #7709, centered approximately at 86.86°S latitude, 76.27°W longitude. It was taken on December 29, 1997, at 3:22 PM PST, on Mars Global Surveyor's 77th orbit around Mars. The Mariner 9 image (DAS #7900063) was taken in 1972 and was the best-resolution image previously acquired. The Viking images date to 1977. The MOC subframe of #7709 was featured as Figure 6a in Malin et al., "Early Views of the Martian Surface from the Mars Orbiter Camera of Mars Global Surveyor," Science, v. 279, no. 5357, pp. 1681-1685.

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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