Mars Global Surveyor
Mars Orbiter Camera
Ridged Terrain on the Floor of Melas Chasma
MGS MOC Release No. MOC2-232, 22 May 2000
50% Size View 810 KBytes
Full Resolution View 3.1 MBytes
Are these dunes? One of the most puzzling findings of the Mars Global
Surveyor Mars Orbiter Camera investigation has been the discovery of
many surfaces of sharp, parallel ridges and grooves that---at first
glance---look like dunes, but upon closer inspection turn out to be
something else. They aren't dunes because they occur too close
together, their crests are too sharp, and their slopes are too symmetrical.
In most places that they occur on Mars, they appear to be occurring
within a specific layer of (usually) dark material.
Exactly what processes make these ridges is a mystery, but it
clearly involves some sort of erosion. Dark mesas in this picture of
the floor of Melas Chasma in the Valles Marineris system are
developing sharp, parallel troughs and pits that appear to eventually
erode to become the fields of ridges seen throughout the rest of the
image. Dark, ridged surfaces like this are common in the central
floors of Valles Marineris and elsewhere in the equatorial regions of
Mars, and present a type of surface that may need to be avoided by
future Mars landers. This image, illuminated by sunlight from the
left, covers an area 3 kilometers (1.9 miles) wide and 14.5 kilometers
(9 miles) long. The scene is located near 8.8°S, 76.8°W and
was acquired on March 22, 1999.
Image 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.
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