Experimental simulation of high mobility processes and exotic pseudolevitation

Planetary surfaces are transformed by various processes at different atmospheric pressures. On Mars, fluids are expected to have flowed at reduced atmospheric pressure during the last 3 billion years. Nevertheless, the influence of low pressure on surface processes has been investigated in only a few studies. Our understanding of the influence of gas in fluids on Martian surface morphologies is poor due to the low number of experiments performed at low atmospheric pressure ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>∼</mml:mo> </mml:math> 7 mbar) and the limited potential analogs on Earth. Here, we present laboratory and numerical experiments to explore the influence of gas production on fluid-sand mobility at low atmospheric pressure. Energetic cohesive sand pellets uplifted by escaping gas were generated, forming narrow channels with levees with lengths of 80–90 cm, which were approximately 1800 times their widths. The maximum experimentally determined velocity of the pellets ranged from 60 to 150 cm/s. The channel morphologies were formed by a pseudo-levitation mechanism corresponding to transport with reduced friction. We propose that the mechanisms observed in our experiments at low atmospheric pressure may explain some past Martian surface changes.