Fig. 1: Hopper flow experiment for regolith simulant in Earth vs. Moon gravity.
From: Behaviors of lunar regolith simulants under varying gravitational conditions
Photographs show JSC-1A lunar regolith simulant flowing through a macroscopic quasi-2D hourglass (hopper angle 60°) at (A) 1.0 G and (B) 0.19 G. The JSC-1A flows smoothly through the hopper-style hourglass to completion under nominal Earth gravity (see arrows in panels A, t = 0 s,0.3 s,0.6 s). Under lunar gravity, the simulant begins to flow smoothly (arrows in panels B, t = 0 s,0.4 s), but it then jams, clogging the orifice (arrows showing clogged orifice in panel B, t = 0.8 s,1.3 s). The system remains clogged until the experiment ends. The total duration of outflow in the Earth gravity experiment is approximately 0.9 s, and 1.3 s in the lunar gravity experiment. Lunar gravity conditions were performed using the ZARM GTB active drop tower (Bremen, Germany).
