Mars Global Surveyor
Mars Orbiter Camera
Alternating Light- and Dark-toned Layers in Holden Crater
MGS MOC Release No. MOC2-262, 4 December 2000
(A) Holden Crater Context
Image source: Viking Orbiter Mosaic, U.S. Geological Survey
|
(B) Layers in Holden Crater
"Colorized" subframe of MOC image M03-02733
|
While many of the layered outcrops in craters and chasms on Mars are
seen as stair-stepped series of cliffs and benches composed of similar
materials with similar thicknesses (e.g., as in the crater at 8°N, 7°W and in Candor Chasma), other layer outcrops are
expressed on relatively smooth, rounded slopes as alternating light
and dark bands. The best example of this variety of layered
sedimentary material is found in southern Holden Crater. Holden is
located at 26.5°S, 33.9°W, and has a diameter of 141 km (88
mi). The context in Picture A, above, shows that a valley, Uzboi
Vallis, enters the crater on its southwestern side. Not too far from
where Uzboi Vallis meets Holden Crater, rounded slopes and buttes
consisting of alternating light and dark bands are seen. The origin
of these layers is not known, but like those found in other craters on
Mars, they might have resulted from deposition of sediment in a lake
that would have occupied Holden Crater. Alternatively, these are
materials deposited by falling out of the air, the same way that volcanic
ash is deposited on Earth. The Viking mosaic (Picture A) images are
illuminated by sunlight from the upper right. The MOC image (Picture
B) is illuminated from the upper left. North is up.
Additional Image Viewing Options:
(A) Holden Crater Context:
(B) Layers in Holden Crater:
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 palette 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
the colors would not look like this to a human observer at Mars.
Images Credit: NASA/JPL/Malin Space Science Systems
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.
To MSSS Home Page
