Microgravity Repose Angle
In collaboration with NASA Glenn Research Center, Carthage students developed and carried out experiments to measure the repose angle of lunar regolith simulants in vacuum under lunar gravity conditions aboard NASA’s reduced gravity aircraft.
Repose angles for lunar mare simulants were measured in rotating drum experiments aboard NASA’s microgravity aircraft, Weightless Wonder. We measured both the maximum critical angle of stability and the static angle of repose for simulants JSC-1A and GRC-3 as a function of drum rotation rate. These measurements were conducted under vacuum to simulate conditions of the 1/6 − g lunar environment, and under standard atmospheric pressure to examine the effects of interstitial gasses on inter-particle cohesivity.
We further investigated a plausible scaling relationship for the dependence of repose angles on effective gravitational acceleration.
The lunar repose experiment consists of three stainless steel drums with quartz viewing windows. Each drum contains a unique regolith simulant and is rotated at precise rates driven by software-controlled PWM units. The regolith dust climbs the wall of the drum until the dynamic angle of repose is achieved and the pile collapses. Maximum angles are measured as a function of drum rotation speed and the relevant scaling parameter (Froude Number) is calculated. The drums can be evacuated to milliTorr levels to approximate the (harder) vacuum of the lunar surface.
2009 NASA SEED
Erin Martin, Samantha Kreppel, Bradley Frye, Isa Fritz, Joseph Monegato
Posters and Presentations
Scaling Relationships for Repose Angles of Lunar Mare Simulants
Reports and Publications
Scaling Relations for Repose Angles of Lunar Mare Simulants (Proceedings Abstract)
(Crosby, K. M.; Fritz, I.; Kreppel, S.; Martin, E.; Pennington, C.; Frye, B.; Agui, J.), Annual Meeting of the Lunar Exploration Analysis Group, held November 16-19, 2009 in Houston, Texas.
Repose Angles of Lunar Mare Simulants in Microgravity
(Isa Fritz, ’10; Samantha Kreppel, ’10; Kevin Crosby; Erin Martin, ’09; Caitlin Pennington, ’09; Brad Frye, ’10; Jose Monegato, ’09; and Agui, J.), Proceedings of the 19th Annual Wisconsin Space Grant (2009).