Saltation impact as a means for raising dust on Mars

Experiments were conducted under atmospheric pressures appropriate for Earth and Mars to determine the e,ciency of sand in saltation as a means for raising dust into the atmosphere under wind speeds which would otherwise be too low for dust entrainment. Experiments involving intimate mixtures of sand and dust (1:1 ratio by mass) showed that after an initial .urry of activity of a few seconds duration, the bed stabilized with little movement of either sand or dust. In contrast, sands set into saltation upwind from dust beds were e,cient in injecting the dust into suspension, with low-pressure Martian conditions being some 4ve times more e,cient than terrestrial conditions. This result is attributed to the higher kinetic energies of the saltating grains on Mars, which is a consequence of the higher velocities of the grains. These results suggest that sands saltating across dust beds on Mars are an e8ective means for setting dust into suspension. ? 2002 Published by Elsevier Science Ltd.