Soil Transport by Winds on Mars

The eolian transport of surface material on the planet Mars is estimated from results of low-pressure wind tunnel testing and theoretical considerations. A semiempirical re ation is developed that will estimate the total amount of surface material moving in eolian saltation, suspension, and surface traction. The estimated total mass movement of surface material per unit width time on the surface of Mars is q = 2.61p(V, V,t)(V, + V,t)2/g (g/cm s), wherep is the density of the atmospheric gas, g is the acceleration due to gravity, and V, and V,t are the friction speed and saltation threshold friction speed, respectively. A flat surface composed ofparticles of nearly uniform size is assumed. A change in the mean particle size changes the threshold friction speed V,t. The path lengths of saltating particles and wavelengths of urface ripples can vary as much as a factor of 2 if the surface t mperature varies from 150 to 250 K. The angles between particle paths and the horizontal surface are calculated to be lower on Mars than on earth, and particles travel much faster on Mars than on earth. The ratio of final particle velocity to threshold friction speed, VF/V,t, is found to be several times that of saltation on earth.