The flowability of fine powders in reduced gravity conditions

Global documentation of gullies with the Mars Reconnaissance Orbiter Context Camera and implications for their formation

“…The new gully flows are observed on slopes as low as 10° (Dundas et al, 2012), much lower than both the typical angle of repose (26-35°depend-ing on climate and material properties (Ritter, 1986)) and slopes on which FCCFs have been observed on Earth (P24°) (Hétu et al, 1994;Hétu and Gray, 2000). This is significant as experiments aboard the NASA KC-135 spacecraft found that with decreasing gravity the dynamic angle of repose increases, scaling as a factor of p g (White and Klein, 1990;Brucks et al, 2007), while the fluidization decreases (Walton et al, 2006;Williams et al, 2007). For example, well-rounded 1.35 mm diameter glass beads under terrestrial gravity were found to have an angle of repose of 30°i n terrestrial gravity and 34°under martian gravity in experiments by White and Klein (1990).…”