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Mars Global Surveyor
Mars Orbiter Camera

Mars Orbiter Camera (MOC) Low Resolution Images
SPO-2 Observations:

Martian North Polar Cap on September 12, 1998


Mars Global Surveyor Mars Orbiter Camera Release:          MOC2-67a, -67b
Mars Global Surveyor Mars Orbiter Camera Image ID:         590062431.55001
							   P550-1 (red wa);
							   P550-2 (blue wa)
(A) 550_1_2_proj_30perc.gif
365 KByte JPEG image

(A) MGS MOC view of the north polar region of Mars obtained on September 12, 1998. The swirled pattern at the top center of the picture is an area of polar layered deposits covered in part by the permanent north polar ice cap. This color composite does not represent the "true" color of Mars. To make the composite, MOC images 55001 (red-band) and 55002 (blue-band) were combined with a green-band synthesized by averaging the red and blue bands. The images have been reprojected to simulate the view that a person would have if the person was located about 1200 kilometers (740 miles) above the planet at 65°N, 275° W.

(B) 55001_ICON.gif
72 KByte GIF image

(B) MOC image 55001 shown at 15% of its original size. This is what the original image looks like before it is projected to a sphere, as was done in (A), above. The image was obtained line-by-line starting from from the right; that is, the spacecraft moved toward the polar cap from the right side of the image, and then moved southward towards the left side of the image. The region shown stretches from about 71°N latitude on the right, over the north pole--90°N--near the center, and down to about 75°N latitude on the left.

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.


Mars Global Surveyor's Mars Orbiter Camera obtained its last SPO-2 images of Mars on September 12, 1998. SPO-2, or "Science Phasing Orbit-2", took place between early June and mid-September 1998. Shown above are MOC wide angle (red and blue band) images of the martian north polar region obtained around 3:15 a.m. PDT on September 12, 1998. The color composite ((A) above) was made using red and blue wide angle MOC images 55001 and 55002--these were the last pictures taken of the planet until the camera resumes its work in late-March 1999.

The north polar layered deposits, a terrain believed composed of ice and dust deposited over millions of years, dominates this view. The swirled pattern in the images above are channels eroded into this deposit. The pattern is accentuated by the illumination and seasonal frost differences that arise on sun-facing slopes during the summer. The permanent portion of the north polar cap covers most of the region with a layer of ice of unknown thickness.

At the time this picture was obtained, the martian northern hemisphere was in the midst of the early Spring season. The margin of the seasonal carbon dioxide frost cap was at about 67° N, so the ground throughout this image is covered by frost. The frost appears pink rather than white; this may result from textural changes in the frost as it sublimes or because the frost is contaminated by a small amount of reddish martian dust. Please note that these pictures have not been "calibrated" and so the colors are not necessarily accurately portrayed.

In addition to the north polar cap, the pictures also show some clouds (bluish-white wisps in (A)). Some of the clouds on the right side of the images are long, linear features that cast similar long, dark shadows on the ground beneath them.

When the MOC resumes imaging of Mars in March 1999, summer will have arrived in the north polar regions and the area surrounding the permanent polar cap will appear much darker than it does here. The dark features surrounding the cap are sand dunes, and these are expected to darken over the next several months as seasonal ice sublimes and is removed from the surface.

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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