The particle size of Martian aeolian dunes

Because dunes consist of a narrow range of well-sorted, unconsolidated particles, they provide for a test of the relationship between particle size and thermal inertia calculated from midinfrared emission data for the Martian surface. Two independent approaches are used. First, thermal inertia data indicate that Martian dunes have an average particle size of about 500 ± 100 μm, or medium to coarse sand. Second, expected dune particle sizes are determined from grain trajectory calculations and the particle size transition from suspension to saltation. Both approaches indicate that Martian dune sand should be coarser than terrestrial dune sand. Results closely match the grain sizes determined from thermal inertia models, providing the first direct test of the validity of these models for actual Martian surface materials. -from Authors