"Safely Rooted on Earth, Scientists Solve an Icy Martian Puzzle," by HenryFountain, The New York Times, March 30, 2004, Section F, page 3.
With attention focused on the surface of Mars, another discovery has beenmade about the "Red Planet," but without the benefit of the rovers. As described in the April issue of Geology, scientist Dr. Jon Pelletier used one modifiedform of the Fitzhugh-Nagumo equations to model an unusual feature of the Martian landscape: the spiral troughs in its polar ice caps.Previous attempts to explain this phenomenon have included such complex factors as wind erosion and ice flows. Pelletier found that a model basedupon "accublation" - the process of ice being heated enough to turn to gas on the sun-facing side of a trough, and then accumulating as ice on theopposite (shadowed) side - was sufficient to generate the spiral patterns. But the spirals on Mar's surface are not perfect: Dr. Pelletier's next stepwill be to create a more realistic model that addresses such factors as initial conditions, climate change, and landforms beneath the ice. Some nice images are on line.
--- Claudia Clark