NASA Mars Odyssey THEMIS Image: Kasei Vallis Topography

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Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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Kasei Vallis is our topic for the weeks of April 18 and 25.

Originating on the margin of Lunae Planum, the Kasei Vallis

complex contains two main channels that run east-west

across Tempe Terra and empty into Chryse Planitia. During

the week of April 18th we will concentrate on the northern

branch of Kasei Vallis. The week of April 25 will be

devoted to the southern branch.

The formation of Kasei Vallis is still being studied and several

theories exist. It is thought that volcanic subsurfaceing

heating in the Tharsis/Lunae Planum region resulted in a release

of water, which carved the channels and produced the landforms

seen within the channels. One theory is that this was a one-time

catastropic event, another theory speculates that several flooding

events occurred over a long time period. Others have proposed

that some of the landforms (especially scour marks and teardrop

shaped “islands”) are the result of glacial flow rather than

liquid flow. Teardrop shaped islands are common in terrestrial

rivers, where the water is eroding material in the channel.

A glacial feature called a drumlin has the exact same

shape, but is formed by deposition beneath continental glaciers.

This VIS image illustrates the complex topography

within Kasei Vallis. The smoother appearing section is the

lowest in elevation and has been filled by deposition. To

either side are eroded banks. The parallel striations running

from lower-left to upper-right can represent: rock layers

eroded to show the layering, terracing – erosion of the rock

by different depths of flow, or scouring caused by material

being ground against the banks by the downstream flow. Terracing

is usually associated with action by liquid water; scour is

generally associated with glacial (ice) flow.

[Source: ASU THEMIS Science Team]

NASA’s Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA’s Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Image Credit: NASA/JPL/Arizona State University