Flowability of lunar regolith simulants under reduced gravity and vacuum in hopper-based conveying devices

Hager, Philipp; Hoehn, A.; Rott, M.; Walter, Ulrich

doi:10.1016/j.jterra.2014.04.005

Cited by 9 publications

(8 citation statements)

References 8 publications

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“…The mechanical characteristics of granular media under different gravity conditions have been experimentally investigated, and it was found that their flow dynamics explicitly depend on the gravitational acceleration 27 . The angle of repose is constant regardless of the gravitational acceleration 28 , 29 , while the friction angle slightly increases as the gravity decreases 30 .…”

Section: Introductionmentioning

confidence: 99%

“…The wheel mobility performance under reduced gravity has also been investigated 31 . The abovementioned studies 27 – 31 employed parabolic flights or drop tower facilities for simulating reduced gravity environments on Earth. These facilities, however, can simulate only limited campaigns: short duration (e.g., a few tens of seconds in parabolic flights), fewer test trials, and unstable gravity conditions 32 .…”

Section: Introductionmentioning

confidence: 99%

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Granular flow experiment using artificial gravity generator at International Space Station

et al. 2023

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Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for space exploration. In this study, we propose an experimental approach to examine a granular flow under stable artificial gravity conditions for a long duration generated by a centrifuge at the International Space Station. We also perform a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verify that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the experimental results reveals that the mass flow rate of granular flow quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Granular flow experiment using artificial gravity generator at International Space Station

et al. 2023

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“…This results in highly cohesive and abrasive particles which can stick to tools and themselves. These properties affect the flow characteristics of regolith, which can lead to clogging, for example, of funnels (Reiss et al, 2014). It is important to consider these characteristics when developing collection and processing equipment, as a blockage could impact the success of the mission (Otto et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Verification of a virtual lunar regolith simulant

Louca,

Vrublevskis,

Eder

et al. 2024

Front. Space Technol.

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Introduction: Physical regolith simulants are valuable tools for developing In-Situ Resource Utilisation hardware. However, using virtual models of regolith instead can reduce costs, limit exposure to hazardous materials, and offer a practical method of testing the effects of reduced gravity.Methods: We verify a virtual model of regolith as macroparticles against physical tests. Using space partitioning techniques to identify neighbouring particles, we present a scalable model of regolith, in which the computation time increases roughly proportionally with the number of particles. We evaluated the performance of this virtual simulant vs. a physical simulant (Exolith LMS-1) by comparing the flow rate through funnels of various diameters, and the resultant angle of repose of material on both large (500 g) and small (16 g) scale tests.Results: For large scale tests, the flow rates were within the predicted range for macroparticles with radii 3–7 mm, with the greatest accuracy achieved for radii 4–5 mm. However, the macroparticles blocked the simulated funnels more easily than in the physical trials, due to their high cohesion. The angle of repose was not accurately represented by this model for either of the tests.Discussion: The high efficiency of this model makes it best suited for applications which require large scale approximations of regolith with real-time execution, such as virtual training for robot operators or providing visual and haptic feedback in model-mediated teleoperation systems. The results of this model in reduced gravity could be further verified against data from upcoming lunar missions in future work.

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“…The wheel mobility performance under reduced gravity has also been investigated 31 . The abovementioned studies [27][28][29][30][31] employed parabolic flights or drop tower facilities for simulating reduced gravity environments on Earth. We note that these facilities can simulate only limited campaigns: short duration (e.g., a few tens of seconds in parabolic flights), fewer test trials, and unstable gravity conditions 32 .…”

Section: Introductionmentioning

confidence: 99%

Granular flow experiment using artificial gravity generator on International Space Station

Ozaki

Ishigami

Otsuki

et al. 2021

Preprint

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Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for space exploration. We performed a granular flow experiment under stable artificial gravity conditions generated by a centrifuge on the International Space Station. We also performed a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verified that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the granular flow results revealed that the mass flow rate quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.

show abstract

Flowability of lunar regolith simulants under reduced gravity and vacuum in hopper-based conveying devices

Cited by 9 publications

References 8 publications

Granular flow experiment using artificial gravity generator at International Space Station

Granular flow experiment using artificial gravity generator at International Space Station

Verification of a virtual lunar regolith simulant

Granular flow experiment using artificial gravity generator on International Space Station

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