Surface Cleanliness Effect on Lunar Soil Shear Strength

Perko, Howard A.; Nelson, John D.; Sadeh, Willy Z.

doi:10.1061/(asce)1090-0241(2001)127:4(371)

Cited by 111 publications

(82 citation statements)

References 14 publications

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“…Moreover, the adhesive force between particles is weakened by surface roughness, because of the increased separation between the surfaces of the particles. 19,20 Therefore, the observed rapid drop in the solid conductivity from the EMB-49.5 to the FGB glass beads is attributed to the difference in the surface texture of the beads. Additionally, the surface texture of the FGB samples differed as seen in FIG.…”

Section: A Effect Of Particle Sizementioning

confidence: 99%

Thermal conductivity model for powdered materials under vacuum based on experimental studies

et al. 2017

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The thermal conductivity of powdered media is characteristically very low in vacuum, and is effectively dependent on many parameters of their constituent particles and packing structure. Understanding of the heat transfer mechanism within powder layers in vacuum and theoretical modeling of their thermal conductivity are of great importance for several scientific and engineering problems. In this paper, we report the results of systematic thermal conductivity measurements of powdered media of varied particle size, porosity, and temperature under vacuum using glass beads as a model material. Based on the obtained experimental data, we investigated the heat transfer mechanism in powdered media in detail, and constructed a new theoretical thermal conductivity model for the vacuum condition. This model enables an absolute thermal conductivity to be calculated for a powder with the input of a set of powder parameters including particle size, porosity, temperature, and compressional stress or gravity, and vice versa. Our model is expected to be a competent tool for several scientific and engineering fields of study related to powders, such as the thermal infrared observation of air-less planetary bodies, thermal evolution of planetesimals, and performance of thermal insulators and heat storage powders. © 2017 Author (s)

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Section: A Effect Of Particle Sizementioning

confidence: 99%

Thermal conductivity model for powdered materials under vacuum based on experimental studies

et al. 2017

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“…From the literature, the factor K is about 5e-2 kg/s 2 and S is about 0.8 [18] [19]. According to [20], it seems impossible to launch particles submitted to such a force (1 µm size dusts undergo a 10 -8 N force).…”

Section: ) Dust Charging On the Surfacementioning

confidence: 99%

New SPIS Capabilities to Simulate Dust Electrostatic Charging, Transport, and Contamination of Lunar Probes

Hess

Sarrailh

Matéo‐Vélez

et al. 2015

IEEE Trans. Plasma Sci.

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Abstract-The Spacecraft Plasma interaction Software (SPIS) has been improved to allow for the simulation of lunar and asteroid dust emission, transport, deposition and interaction with a spacecraft on or close to the lunar surface. The physics of dust charging and of the forces that they are subject to has been carefully implemented in the code. It is both a tool to address the risks faced by lunar probes on the surface, and a tool to study the dust transport physics. We hereby present the details of the physics that has been implemented in the code, as well as the interface improvements that allow for a user friendly insertion of the lunar topology and of the lander in the simulation domain. A realistic case is presented that highlights the capabilities of the code as well as some general results about the interaction between a probe and a dusty environment.

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“…This phenomenon is in agreement with the test results of the Surveyor 7 spacecraft on the lunar surface. 20) At any moment during the sampling process, the real-time positions, velocities and forces of all the lunar regolith particles are monitored. The final mass of the sample soil in the bucket is counted as 287.07 g. Figure 9 shows the applied force and torque curves of the bucket during the sampling process.…”

Section: Dynamic Simulation Of Lunar Soilmentioning

confidence: 99%

Simulation and Analysis of the Lunar Regolith Sampling Process Based on the Discrete Element Method

Liu

Cheng

Liang

et al. 2014

Trans. Japan Soc. Aero. S Sci.

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The regolith sampling process is risky but a key procedure in planet exploration. It not only accounts for the uncertainty of the soil particles that interacted with the bucket, but also the automated operation of the sampling manipulator. In this paper, the sampling process for lunar regolith, which involves the coupling between the microscopic lunar soil particles and macroscopic sampling mechanism, is analyzed. A discrete element model (DEM) that considers the torsion, bending and equivalent attraction between two particles is proposed for lunar soil modeling, whose microscopic parameters are calibrated based on tri-axial experimental results. Then a dynamic model for a lunar sampling manipulator is established using Lagrange formulations, and operation space control is applied to the manipulator to make the bucket move along the expected excavation trajectory. The numerical results show the whole sampling procedure, which considers the interaction between lunar soil and the bucket approaching a realistic situation. The operation space control schema is validated during the excavation simulation process, confirming the methods and model can support the performance analysis and design of a sampling mechanism for lunar explorations.

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Surface Cleanliness Effect on Lunar Soil Shear Strength

Cited by 111 publications

References 14 publications

Thermal conductivity model for powdered materials under vacuum based on experimental studies

Thermal conductivity model for powdered materials under vacuum based on experimental studies

New SPIS Capabilities to Simulate Dust Electrostatic Charging, Transport, and Contamination of Lunar Probes

Simulation and Analysis of the Lunar Regolith Sampling Process Based on the Discrete Element Method

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