NASA Mars Odyssey THEMIS Image: North Polar Cap (26 October 2004)

Image Context:


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.

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