Threshold Velocity of Wind-Blown Sand on Low-Pressure Martian Surface

Wind-blown sand transport is a prominent process on Mars; however, current models may systematically overestimate the threshold friction velocity u*t critical for predicting aeolian processes. We remeasured the u*t of a new Martian soil simulant in a low-pressure wind tunnel and examined its variation under ambient pressures ranging from 700 Pa to 1500 Pa. The results indicate that u*t values are approximately 38.7% lower than those predicted by earlier models and experimental measurements. A calibrated model predicts a minimum threshold friction velocity of 0.96 m s-1, corresponding to near-surface wind speeds between 9.3 m s-1and 23 m s-1 at a height of 1.5 m above the Martian surface, with a shear stress of approximately 0.02 Pa, which is consistent with the data recorded by the NASA Perseverance rover during dust-lifting events. The newly determined u*t further resolves the discrepancies between Martian-based observations, theoretical models, and terrestrial-based measurements, providing a more robust basis for reliable estimates of Martian aeolian sediment transport. The results contribute to advancing understanding of the mechanisms driving Martian wind-blown sand activity and their role in shaping the planet's geomorphological evolution.