A lower-than-expected saltation threshold at Martian pressure and below

Abstract

Aeolian sediment transport is observed to occur on Mars as well as other extraterrestrial environments, generating ripples and dunes as on Earth. The search for terrestrial analogues of planetary bedforms, as well as environmental simulation experiments able to reproduce their formation in planetary conditions, are powerful ways to question our understanding of geomorphological processes towards unusual environmental conditions. Here, we perform sediment transport laboratory experiments in a closed-circuit wind tunnel placed in a vacuum chamber and operated at extremely low pressures to show that Martian conditions belong to a previously unexplored saltation regime. The threshold wind speed required to initiate saltation is only quantitatively predicted by state-of-the art models up to a density ratio between grain and air of $4\times 10^5$, but unexpectedly falls to much lower values for higher density ratios. In contrast, impact ripples, whose emergence is continuously observed on the granular bed over the whole pressure range investigated, display a characteristic wavelength and propagation velocity essentially independent of pressure. A comparison of these findings with existing models suggests that sediment transport at low Reynolds number but high grain-to-fluid density ratio may be dominated by collective effects associated with grain inertia in the granular collisional layer.

arXiv comment38 pages, 21 figures

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Cited by in corpus (11)

• Modeling high-speed gas-particle flows relevant to spacecraft landings: A review and perspectives
• Aeolian sand transport: Scaling of mean saltation length and height and implications for mass flux scaling
• Coevolving aerodynamic and impact ripples on Earth
• Single-dopant band bending fluctuations in MoSe${}_2$ measured with electrostatic force microscopy
• Anomalous Scaling of Aeolian Sand Transport Reveals Coupling to Bed Rheology
• Scaling laws for planetary sediment transport from DEM-RANS numerical simulations
• Hydrodynamic roughness induced by a multiscale topography
• Aerodynamic roughness of rippled beds under active saltation at Earth-to-Mars atmospheric pressures
• Emergence of wind ripples controlled by mechanics of grain-bed impacts
• From lab to landscape-scale experiments for the morphodynamics of sand dunes
• Ejected Particles after Impact Splash on Mars: Aggregates and Aerodynamics