Mars Global Surveyor
Mars Orbiter Camera

Evidence for Recent Liquid Water on Mars:
Gullies in Gorgonum Chaos

MGS MOC Release No. MOC2-236, 22 June 2000


(A) Gullies Close-up

50%-size Color 280 KBytes
Full Resolution Color 935 KBytes

50%-size B&W 225 KBytes
Full Resolution B&W 755 KBytes

(B) The Long View

Small Color 570 KBytes
Large Color 2.1 MBytes

Small B&W 490 KBytes
Large B&W 1.9 MBytes

(C) Viking Context View

60%-size Context 140 KBytes
100%-size Context 305 KBytes

50% Viking Image 300 KBytes
100% Viking Image 990 KBytes

The first two pictures (above) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture on the left (A) is a portion of the picture in the middle (B). The Viking view (C) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping ground water emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region.

The MOC pictures were taken on January 22, 2000. The sample on the left (A) is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (B) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (C) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.

Images Credit: NASA/JPL/Malin Space Science Systems

For Media/Print purposes:

Here are full-resolution views of the long Gorgonum Chaos image. These are too long for some web browsers (in these cases, you must save the link to your desktop and view with other software):

A brief description of how the color was generated:

The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallete of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to each gray level. This is only a crude approximation of martian color and should only be considered representative of Mars. It is likely Mars would not look like this to a human observer at Mars.

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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