NASA Mars Odyssey THEMIS Image: North Polar Cap

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Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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This week we will be looking at five examples of laminar wind

flow on the north polar cap. On Earth, gravity-driven south

polar cap winds are termed “catabatic” winds. Catabatic

winds begin over the smooth expanse of the cap interior due

to temperature differences between the atmosphere and the

surface. Once begun, the winds sweep outward along the surface

of the polar cap toward the sea. As the polar surface slopes

down toward sealevel, the wind speeds increase. Catabatic

wind speeds in the Antartic can reach several hundreds of miles

per hour.

In the images of the Martian north polar cap we can see

these same type of winds. Notice the streamers of dust

moving downslope over the darker trough sides, these

streamers show the laminar flow regime coming off the cap.

Within the trough we see turbulent clouds of dust, kicked

up at the trough base as the winds slow down and enter a

chaotic flow regime.

The horizontal lines in these images are due to framelet

overlap and lighting conditions over the bright polar cap.

[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