Mars Global Surveyor
Mars Orbiter Camera

Mars Orbiter Camera (MOC) High Resolution Images

July 20, 1998
Moon/Mars Landing Commemorative Release:
Gusev Crater and Ma'adim Vallis


Mars Global Surveyor Mars Orbiter Camera Release:          MOC2-58a, -58b, -58c, -58d
Mars Global Surveyor Mars Orbiter Camera Image ID:         577869444.25905
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(A) Gusev Crater and Ma'adim Vallis. Gusev Crater is approximately 150 kilometers (93 miles) across. Ma'adim Vallis is the nearly straight canyon that enters Gusev Crater from the lower right. White box indicates the location of MOC image 25905, shown below in (C). Picture is a high resolution digital image mosaic of Viking Orbiter images prepared by the U.S. Geological Survey. North is up, illumination is from the upper left.

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(B) Close-up of southern Gusev Crater and the location (white box) of MOC image 25905. Ma'adim Vallis is the canyon that enters Gusev Crater at the lower center of the frame. Compare with (A) for context. Picture is a U.S. Geological Survey digital image mosaic of Viking Orbiter images. The white box is approximately 15 kilometers (9.3 miles) wide and 35.5 kilometers (22 miles) long. North is up, illumination is from the upper left.

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(C) The MOC image 25905, shown at 40% of its original size. At this size, the image resolution is 18.3 meters (60 feet) per pixel. The white box indicates the location of the subframe shown at full resolution in (D). North is approximately up, illumination is from the lower right.

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(D) Floor of Ma'adim Vallis, seen at 7.3 meters (24 feet) per pixel. Subframe of MOC image 25905. See (C) above for context. North is approximately up, 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.


On July 20, 1969, the first human beings landed on the Moon. On July 20, 1976, the first robotic lander touched down on Mars. This July 20th-- 29 years after Apollo 11 and 22 years since the Viking 1 Mars landing-- we take a look forward toward one possible future exploration site on the red planet.

One of the advantages of the Mars Global Surveyor Mars Orbiter Camera (MOC) over its predecessors on the Viking and Mariner spacecraft is resolution. The ability to see--resolve--fine details on the martian surface is key to planning future landing sites for robotic and, perhaps, human explorers that may one day visit the planet.

At present, NASA is studying potential landing sites for the Mars Surveyor landers, rovers, and sample return vehicles that are scheduled to be launched in 2001, 2003, and 2005. Among the types of sites being considered for these early 21st Century landings are those with "exobiologic potential"--that is, locations on Mars that are in some way related to the past presence of water.

For more than a decade, two of the prime candidates suggested by various Mars research scientists are Gusev Crater and Ma'adim Vallis. Located in the martian southern cratered highlands at 14.7° S, 184.5° W, Gusev Crater is a large, ancient, meteor impact basin that--after it formed--was breached by Ma'adim Vallis.

Viking Orbiter observations provided some evidence to suggest that a fluid--most likely, water--once flowed through Ma'adim Vallis and into Gusev Crater. Some scientists have suggested that there were many episodes of flow into Gusev Crater (as well as flow out of Gusev through its topographically-lower northwestern rim). Some have also indicated that there were times when Ma'adim Vallis, also, was full of water such that it formed a long, narrow lake.

The possibility that water flowed into Gusev Crater and formed a lake has led to the suggestion that the materials seen on the floor of this crater--smooth-surfaced deposits, buried craters, and huge mesas near the mouth of Ma'adim Vallis--are composed of sediment that eroded out of the highlands to the south of Gusev Crater. In 1995, the Exobiology Program Office at NASA Headquarters produced a report, An Exobiological Strategy for Mars Exploration (NASA SP-530), that included Gusev Crater as a possible priority site for future Mars exploration because it might once have been a lake.

At 12:17 a.m. (PDT) on April 24, 1998--during Mars Global Surveyor's 259th orbit--MOC obtained the high resolution image of Gusev Crater and Ma'adim Vallis shown above, in part to test some of the proposed hypotheses. The raw image has a scale of 7.3 meters (24 feet) per pixel. At this scale, there are no obvious shorelines that would indicate the past presence of a lake in either Ma'adim Vallis or Gusev Crater. There are several alternative explanations for this absence, including:

When Mars Global Surveyor achieves its Mapping Orbit in March 1999, MOC will have the ability to obtain pictures with resolutions around 1.5 meters (5 feet) per pixel. Sometime during the mapping mission, it may be possible to image Gusev Crater again to look for potential lake features and possible future landing sites.

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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