Mars Global Surveyor
Mars Orbiter Camera

Mars Orbiter Camera Views the "Face on Mars"

Shortly after midnight Sunday morning (5 April 1998 12:39 AM PST), the Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft successfully acquired a high resolution image of the "Face on Mars" feature in the Cydonia region. The image was transmitted to Earth on Sunday, and retrieved from the mission computer data base Monday morning (6 April 1998). The image was processed at the Malin Space Science Systems (MSSS) facility 9:15 AM and the raw image immediately transferred to the Jet Propulsion Laboratory (JPL) for release to the Internet. The images shown here were subsequently processed at MSSS.

The picture was acquired 375 seconds after the spacecraft's 220th close approach to Mars. At that time, the "Face", located at approximately 40.8° N, 9.6° W, was 275 miles (444 km) from the spacecraft. The "morning" sun was 25° above the horizon. The picture has a resolution of 14.1 feet (4.3 meters) per pixel, making it ten times higher resolution than the best previous image of the feature, which was taken by the Viking Mission in the mid-1970's. The full image covers an area 2.7 miles (4.4 km) wide and 25.7 miles (41.5 km) long.

Weather Conditions at the Time of Imaging

Winter clouds cover much of the northern hemisphere of Mars above 40° N latitude at this time of the martian year. An image of the Viking Lander 2 site (at 44° N) taken just over a day ago was completely obscured by clouds. The image below shows a color composite made from the red and blue wide angle cameras (the green component is synthesized from the average of the red and blue frames). The small box marks the location of the high resolution image. As can be seen, fortuitously, the area imaged was relatively clear, although the lack of surface definition in many nearby areas, and the low contrast of the raw MOC high resolution image, suggests haze or fog over much of the area.


Color Wide Angle Image of Cydonia taken at same time as High Resolution Image
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Location Images

The first two images below this paragraph are the best Viking pictures of the area in Cydonia where the "Face" is located. For more information about the "Face" and the Viking images, see http://www.msss.com/education/facepage/face.html. Marked on the two images is the "footprint" of the high resolution (narrow angle) camera. Also marked on the second of the images is a dashed box outlining the area seen in enlarged views.

The third view is a one-quarter scale version of the full MOC image, presented to show the "Face" in relation to the features in its immediate vicinity. This image has been processed to enhance features and project it into a mercator map perspective.


035a72.map
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070a13.map
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Full swath at 1/4th resolution
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Raw and Raw stretched

The images below this paragraph are portions of the raw image, and a slightly contrast enhanced version of the raw image, that include the "Face." The full raw image can be retrieved from the JPL WWW site by selecting either the MGS icon (the upper right of the four icons shown on that page) or by going to one of the many JPL Mars mirror sites.

NOTE: The raw images shown immediately below (and on the JPL site) are flipped left to right from the others shown on this page because of the scan direction of the camera. All other images shown have had their orientation corrected for this scan relationship.


Section of raw image
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Contrast enhanced raw image
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Processing

Image processing has been applied to the images in order to improve the visibility of features. This processing included the following steps:

  1. The image was processed to remove the sensitivity differences between adjacent picture elements. This removes the vertical streaking.

  2. The contrast and brightness of the image was adjusted, and "filters" were applied to enhance detail at several scales.

  3. The image was then geometrically warped to meet the computed position information for a mercator-type map. This corrected for the left-right flip, and the non-vertical viewing angle (about 45° from vertical), but also introduced some vertical "elongation" of the image for the same reason Greenland looks larger than Africa on a mercator map of the Earth.

  4. A section of the image, containing the "Face" and a couple of nearly impact craters and hills, was "cut" out of the full image and reproduced separately, as seen below.

For additional information on image processing, see:

http://www.msss.com/education/facepage/vikingproc.html.


Calibrated, mercator map-projected (flipped left to right), contrast enhanced, filtered
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Brightness-inverted (dark to light) version of calibrated, mercator map-projected (flipped left to right), contrast enhanced, filtered
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Just the "Face"
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Comparison of the Best Viking and Reduced Resolution MOC Images

In the comparison below, the best Viking image has been enlarged to 3.3 times its original resolution, and the MOC image has been decreased by a similar 3.3 times, creating images of roughly the same size. In addition, the MOC images have been geometrically transformed to a more overhead projection (different from the mercator map projection of the preceding images) for ease of comparison with the Viking image. The left image is a portion of Viking Orbiter 1 frame 070A13, the middle image is a portion of MOC frame 22003 shown normally, and the right image is the same MOC frame but with the contrast reversed (that is, light features were forced to be dark, and dark features were forced to be light) to simulate the approximate lighting conditions of the Viking image.


Comparison of best Viking with two versions of MOC image
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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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Contact: info@msss.com