Red Planet: Catabatic Winds

Mars 2001 Odyssey
North Polar Cap (Released 25 October 2004)
Image Credit: NASA/JPL/Arizona State University

On Earth, gravity-driven south polar cap winds are termed "catabatic" winds. They are caused by the downward motion of cold air. 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 Antarctic 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 one sees 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.

Mars 2001 Odyssey
North Polar Cap (Released 27 October 2004)
Image Credit: NASA/JPL/Arizona State University

The dry valleys in Antarctica are a favorite spot for geologists and microbiologists to look for unusual terrestrial phenomenon. Mars itself is often compared to these low-humidity regions, the only continental part of Antarctica that is largely devoid of ice. Despite the harsh conditions, plants and microbial life are not absent, a result that offers intriguing clues to adaptability of life on Earth.

2001 Mars Odyssey launched on April 7, 2001, and arrived at Mars on October 24, 2001. The mission is mapping the amount and distribution of chemical elements and minerals that make up the Martian surface. The spacecraft especially looks for hydrogen, most likely in the form of water ice, in the shallow subsurface of Mars.

One of its three primary instruments is called THEMIS (Thermal Emission Imaging System), for determining the distribution of minerals, particularly those that can only form in the presence of water. It also provides the communications relay for U.S. and international landers, including missions in NASA’s Mars Program, the Mars Exploration Rovers. The name "2001 Mars Odyssey" was selected as a tribute to the vision and spirit of space exploration as embodied in the works of renowned science fiction author Arthur C. Clarke.

Related Web Pages

Jet Propulsion Laboratory
Malin Space Systems
Mars Global Surveyor
Arizona State THEMIS
Mars 2001 Odyssey