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NASA NTRS2008

Extant and Extinct Lunar Regolith Simulants: Modal Analyses of NU-LHT-1M and -2m, OB-1, JSC-1, JSC-1A and -1AF,FJS-1, and MLS-1

This work is part of a larger effort to compile an internally consistent database on lunar regolith (Apollo samples) and lunar regolith simulants. Characterize existing lunar regolith and simulants in terms of: a) Particle type; b) Particle size distribution; c) Particle shape distribution; d) Bulk density; and e) Other compositional characteristics. Evaluate regolith simulants (Figure of Merit) by above properties by comparison to lunar regolith (Apollo sample) This presentation covers new data on lunar simulants.

Schrader, Christian↗
NASA NTRS2006

Development of Standardized Lunar Regolith Simulant Materials

Lunar exploration requires studies using standardized testing procedures. Previous lunar simulants focused on physical aspects of the lunar regolith. Renewed lunar exploration requires standardized lunar regolith simulant (SLRS) materials that simulate the physical, chemical, and mineralogical properties of the regolith [l]. A root simulant models an end-member, and a derivative is formed by addition of material [2]. The 2005 Workshop recommended a low-Ti mare basalt and a high-Ca highland anorthosite set of roots. Derivatives involve addition of ilmenite and glassy agglutinates [3]. An ideal SLRS material is homogeneous. Geochemical standards are finely-ground to reduce chemical variability, but lunar simulants have a grain size variation and mineralogy that must match the lunar regolith. The simulant homogeneity is monitored using major, minor, and trace element data of progressively smaller samples compared to bulk material. Both chemical and geotechnical properties depend on the contrast from grain to grain. The variability of simulant material is an inherent property that must be taken into account. Simulant production requires monitoring of adherence to simulant requirements and homogeneity during production. Quality control establishes a traceability to a master set of reference standards.

Carpenter, P.↗
NASA NTRS2023

RF Metrology of Lunar Highlands Regolith Simulant NU-LHT-2M

Understanding the electrical properties of lunar regolith is vital to modeling radiofrequency(RF) propagation on the lunar surface a fundamental step in planning lunar surface missions. Near the lunar south pole, the regolith has yet to be directly sampled and thus there remains uncertainty in the electrical properties of the regolith. The regolith simulant NU-LHT-2M is a highlands simulant that is representative of the expected chemical composition of the regolith near the lunar south pole. Previous studies have investigated properties of NU-LHT at UHF and S-band[1]. Future missions to the lunar south pole are expected to utilize X and Ka-band for direct-to-Earth links and UHF, S-band, C-band, and Ka-band for lunar surface communication[2]. As a result, it is necessary to electrically characterize the lunar regolith at these frequencies. In this paper, coaxial impedance dielectric reflectometry is performed on the NU-LHT-2M simulant using a commercially available soil permittivity measurement device. This study serves as a preliminary measurement of the simulant and may lead to enhanced efficacy of the measurement hardware for future applications.

simulant↗
NASA NTRS2006

Standard Lunar Regolith Simulants for Space Resource Utilization Technologies Development: Effects of Materials Choices

As NASA turns its exploration ambitions towards the Moon once again, the research and development of new technologies for lunar operations face the challenge of meeting the milestones of a fastpace schedule, reminiscent of the 1960's Apollo program. While the lunar samples returned by the Apollo and Luna missions have revealed much about the Moon, these priceless materials exist in too scarce quantities to be used for technology development and testing. The need for mineral materials chosen to simulate the characteristics of lunar regoliths is a pressing issue that is being addressed today through the collaboration of scientists, engineers and NASA program managers. The issue of reproducing the properties of lunar regolith for research and technology development purposes was addressed by the recently held 2005 Workshop on Lunar Regolith Simulant Materials at Marshall Space Flight Center. The recommendation of the workshop of establishing standard simulant materials to be used in lunar technology development and testing will be discussed here with an emphasis on space resource utilization. The variety of techniques and the complexity of functional interfaces make these simulant choices critical in space resource utilization.

Sibille, Laurent↗
NASA NTRSDate not supplied

Quantitative Characterization of Lunar Regolith Simulants for Direct Comparison to Apollo Soil Samples

Introduction: Sustained characterization efforts of lunar regolith simulant properties are not only integral for verification of commercially-produced material designed for a wide array of testing applications but are also necessary in establishing a comprehensive comparison to a lunar reference source. As a resource for the lunar science and engineering communities, the Simulant Development Lab (SDL) within the Astromaterials Research & Exploration Science (ARES) division at the Johnson Space Center (JSC) is actively pursuing closure of existing knowledge gaps in fundamental simulant attributes, including chemistry, mineralogy, particle size distribution, particle geometry, bulk and relative density, magnetic susceptibility, and shear strength (i.e., cohesion and angle of internal friction), as well as producing Figures of Merit for comparison of lunar simulants to Apollo regolith samples.

R. Kovtun↗
NASA NTRS2006

Development of Standardized Lunar Regolith Simulant Materials

Lunar exploration requires scientific and engineering studies using standardized testing procedures that ultimately support flight certification of technologies and hardware. It is necessary to anticipate the range of source materials and environmental constraints that are expected on the Moon and Mars, and to evaluate in-situ resource utilization (ISRU) coupled with testing and development. Physical properties of the regolith dominate processes such as excavation and drilling, while chemical properties dominate processes such as elemental extraction. We describe here the development of standardized lunar regolith simulant (SLRS) materials that are traceable interlaboratory standards for testing and technology development. These SLRS materials must simulate the lunar regolith in terms of physical, chemical, and mineralogical properties. A comprehensive simulant development program has been outlined and is in progress. A summary of these issues is contained in the 2005 Workshop on Lunar Regolith Simulant Materials

Carpenter, P.↗
NASA NTRS2006

Characterization of Standardized Lunar Regolith Simulant Materials

Lunar exploration requires scientific and engineering studies using standardized testing procedures that ultimately support flight certification of technologies and hardware. This motivates the development of traceable, standardized lunar regolith simulant (SLRS) materials. For details, refer to the 2005 Workshop on Lunar Regolith Simulant Materials.

Carpenter, P.↗
NASA NTRSDate not supplied

RF Metrology of Lunar Highlands Regolith Simulant NU-LHT-2M

*Presentation for the publication* Understanding the electrical properties of lunar regolith is vital to modeling radiofrequency (RF) propagation on the lunar surface, a fundamental step in planning lunar surface missions. Near the lunar south pole, the regolith has yet to be directly sampled and thus there remains uncertainty in the electrical properties of the regolith. The regolith simulant NU-LHT-2M is a highlands simulant that is representative of the expected chemical composition of the regolith near the lunar south pole. Previous studies have investigated properties of NU-LHT at UHF and S-band[1]. Future missions to the lunar south pole are expected to utilize X and Ka-band for direct-to-Earth links and UHF, S-band, C-band, and Ka-band for lunar surface communication [2]. As a result, it is necessary to electrically characterize the lunar regolith at these frequencies. In this paper, coaxial impedance dielectric reflectometry is performed on the NU-LHT-2M simulant using a commercially available soil permittivity measurement device. This study serves as a preliminary measurement of the simulant and may lead to enhanced efficacy of the measurement hardware for future applications.

simulant↗
NASA NTRS2009

Elements of Regolith Simulant's Cost Structure

The cost of lunar regolith simulants is much higher than many users anticipate. After all, it is nothing more than broken rock. This class will discuss the elements which make up the cost structure for simulants. It will also consider which elements can be avoided under certain circumstances and which elements might be altered by the application of additional research and development.

Rickman, Douglas L.↗
NASA NTRS2011

Hydrogen Reduction of Lunar Regolith Simulants for Oxygen Production

Hydrogen reduction of the lunar regolith simulants JSC-1A and LHT-2M is investigated in this paper. Experiments conducted at NASA Johnson Space Center are described and are analyzed utilizing a previously validated model developed by the authors at NASA Glenn Research Center. The effects of regolith sintering and clumping, likely in actual production operations, on the oxygen production rate are studied. Interpretations of the obtained results on the basis of the validated model are provided and linked to increase in the effective particle size and reduction in the intra-particle species diffusion rates. Initial results on the pressure dependence of the oxygen production rate are also presented and discussed

Hegde, U.↗
NASA NTRSDate not supplied

Behaviors of Lunar Regolith Simulant Under Varying Gravitational Conditions

Understanding the behavior of regolith in varying gravity conditions is critical for space exploration and future missions. In this work, the gravity-driven hopper flow of lunar regolith simulant in different gravitational accelerations (terrestrial, lunar) is first observed experimentally. Numerical simulations (DEM) are then developed to understand the role which cohesive inter-particle forces play in such gravity-driven flow, using the theoretical framework of granular Bond number. Qualitative comparison between a terrestrial experiment and numerical simulation validated this framework. Following that, we numerically studied the dynamic behavior under varying gravitational conditions (from terrestrial to lunar to asteroid gravitational accelerations). We find that this behavior is extremely sensitive to the interplay of the gravity conditions and the attractive/cohesive forces among particles. The numerical and experimental results show that the complex interaction of these forces can drastically change the dynamics of the material producing effects relevant for variable gravity applications.

Soft Matter↗
NASA NTRS2008

Analysis of Lunar Highland Regolith Samples from Apollo 16 Drive Core 64001/2 and Lunar Regolith Simulants - An Expanding Comparative Database

We present modal data from QEMSCAN(registered TradeMark) beam analysis of Apollo 16 samples from drive core 64001/2. The analyzed lunar samples are thin sections 64002,6019 (5.0-8.0 cm depth) and 64001,6031 (50.0-53.1 cm depth) and sieved grain mounts 64002,262 and 64001,374 from depths corresponding to the thin sections, respectively. We also analyzed lunar highland regolith simulants NU-LHT-1M, -2M, and OB-1, low-Ti mare simulants JSC-1, -lA, -1AF, and FJS-1, and high-Ti mare simulant MLS-1. The preliminary results comprise the beginning of an internally consistent database of lunar regolith and regolith simulant mineral and glass information. This database, combined with previous and concurrent studies on phase chemistry, bulk chemistry, and with data on particle shape and size distribution, will serve to guide lunar scientists and engineers in choosing simulants for their applications. These results are modal% by phase rather than by particle type, so they are not directly comparable to most previously published lunar data that report lithic fragments, monomineralic particles, agglutinates, etc. Of the highland simulants, 08-1 has an integrated modal composition closer than NU-LHT-1M to that of the 64001/2 samples, However, this and other studies show that NU-LHT-1M and -2M have minor and trace mineral (e.g., Fe-Ti oxides and phosphates) populations and mineral and glass chemistry closer to these lunar samples. The finest fractions (0-20 microns) in the sieved lunar samples are enriched in glass relative to the integrated compositions by approx.30% for 64002,262 and approx.15% for 64001,374. Plagioclase, pyroxene, and olivine are depleted in these finest fractions. This could be important to lunar dust mitigation efforts and astronaut health - none of the analyzed simulants show this trend. Contrary to previously reported modal analyses of monomineralic grains in lunar regolith, these area% modal analyses do not show a systematic increase in plagiociase/pyroxene as size fraction decreases.

Schrader, Christian M.↗
NASA NTRS2005

DEVELOPMENT OF STANDARDIZED LUNAR REGOLITH SIMULANT MATERIALS

Lunar exploration activities require scientific and engineering studies that use standardized testing procedures and ultimately support flight certification of hardware and the development of technologies for their use on the lunar surface. It is necessary to anticipate the full range of source materials and environmental constraints that are expected on the Moon and Mars, and to evaluate in-situ resource utilization (ISRU) coupled with testing and development. Historical use of lunar simulants has focused on physical aspects of the lunar regolith for landing and transportation activities. Lunar mare simulants MLS-1 and JSC-1 have been developed, but supplies have been exhausted. Renewed emphasis on exploration and ISRU activities requires development of standardized simulant reference materials that are traceable interlaboratory standards for testing and simulate the lunar regolith in terms of physical, chemical, and mineralogical properties. This new generation of lunar regolith simulants must therefore support both technological development and testing methods. These issues were extensively discussed at the 2005 Lunar Regolith Simulant Materials Workshop.

Carpenter, P.↗
NASA NTRS2022

Regolith Simulant Preparation and Geotechnical Characterization for Plume Surface Interaction Testing

Descent engine plumes interact with the lunar surface and accelerate regolith particles to potentially high velocities. These ejecta create risks to surface assets that have yet to be fully assessed. To better understand these risks, plume surface interactions can be simulated on the ground by firing a test engine plume into a bin of lunar regolith simulant under vacuum conditions. The dynamics of the resultant ejecta can then be recorded. In this technical memorandum we discuss the processes used in preparing a 150 kg bin of lunar regolith simulant for plume surface interaction ground tests under vacuum conditions for the NASA STMD Plume Surface Interaction project. We present our approach to mitigating regolith simulant eruptions during pump-down, the methods used to fill and reset the regolith simulant bin for each test, and the techniques used to characterize the consistency of regolith simulant geotechnical properties before each new firing. The challenges of preparing a regolith simulant test bin below an ambient pressure of one atmosphere, particularly on the large scale, could largely be overcome with a system that could fill the test bin with simulant inside the chamber and under vacuum conditions.

lunar regolith↗
NASA NTRSDate not supplied

Gas Permeability of Lunar Regolith Simulants

Lunar lander descent engines produce plume-surface interactions (PSI) effect that can generate high-speed regolith ejecta which can pose a risk to surface and orbital assets. The physics of plume-surface interactions during the descent and landing of a lunar lander depends on the gas permeability of the lunar surface regolith. This presentation will discuss gas permeability measurements that have been performed at NASA Kennedy Space Center to help inform the development of plume-surface interaction models and large-scale PSI ground tests. Results will be presented of gas permeability measurements for lunar regolith simulants that were conducted under vacuum conditions as a function of the granular mineral material's mass density, compaction, and water content.

gas permeability↗
NASA NTRS2013

Preparation of a Frozen Regolith Simulant Bed for ISRU Component Testing in a Vacuum Chamber

In-Situ Resource Utilization (ISRU) systems and components have undergone extensive laboratory and field tests to expose hardware to relevant soil environments. The next step is to combine these soil environments with relevant pressure and temperature conditions. Previous testing has demonstrated how to incorporate large bins of unconsolidated lunar regolith into sufficiently sized vacuum chambers. In order to create appropriate depth dependent soil characteristics that are needed to test drilling operations for the lunar surface, the regolith simulant bed must by properly compacted and frozen. While small cryogenic simulant beds have been created for laboratory tests, this scale effort will allow testing of a full 1m drill which has been developed for a potential lunar prospector mission. Compacted bulk densities were measured at various moisture contents for GRC-3 and Chenobi regolith simulants. Vibrational compaction methods were compared with the previously used hammer compaction, or "Proctor", method. All testing was done per ASTM standard methods. A full 6.13 m3 simulant bed with 6 percent moisture by weight was prepared, compacted in layers, and frozen in a commercial freezer. Temperature and desiccation data was collected to determine logistics for preparation and transport of the simulant bed for thermal vacuum testing. Once in the vacuum facility, the simulant bed will be cryogenically frozen with liquid nitrogen. These cryogenic vacuum tests are underway, but results will not be included in this manuscript.

Klenhenz, Julie↗
NASA NTRS2008

Analysis of Lunar Highland Regolith Samples From Apollo 16 Drive Core 64001/2 and Lunar Regolith Simulants - an Expanding Comparative Database

This slide presentation reviews the work to analyze the lunar highland regolith samples that came from the Apollo 16 core sample 64001/2 and simulants of lunar regolith, and build a comparative database. The work is part of a larger effort to compile an internally consistent database on lunar regolith (Apollo Samples) and lunar regolith simulants. This is in support of a future lunar outpost. The work is to characterize existing lunar regolith and simulants in terms of particle type, particle size distribution, particle shape distribution, bulk density, and other compositional characteristics, and to evaluate the regolith simulants by the same properties in comparison to the Apollo sample lunar regolith.

Schrader, Christian M.↗
NASA NTRSDate not supplied

ISRU Pilot Excavator Wheel Testing in Lunar Regolith Simulant

The ISRU Pilot Excavator, or IPEx, is a robotic excavator funded by NASA’s Space Technology Mission Directorate (STMD). The Concept of Operations for IPEx involves the robot driving on the lunar surface up to 70 km at a speed of up to 30 cm/s. As such, it is critical to the mission’s success to optimize the design of the wheels for performance in lunar conditions, specifically in lunar regolith. To achieve this, an array of tests was completed to observe the effects of various wheel design choices on the driving performance of the wheels in lunar regolith simulant. In order to facilitate testing, we designed a 12” dia. configurable wheel to allow for interchangeability between various wheel formations. Two types of wheel parts were designed to be swapped: cleats, which form the tread of the wheel; and grousers, which protrude from the treads. The test variables that we considered were as follows: square vs. round wheel shape, solid vs. perforated cleats, cleat spacing, grouser height, and grouser spacing. By combining different settings of each of these test variables, ten discrete wheel designs were created and tested. The configurable test wheels were mounted on the Regolith Advanced Surface Systems Operations Robot (RASSOR) developed at NASA’s Kennedy Space Center. In our experiments, the robot was driven at a controlled speed across a prepared surface of BP-1 lunar regolith simulant. Four types of tests were conducted: circle driving, straight driving, slope driving, and drawbar pull. The driving tests were chosen to mimic a variety of conditions in which IPEx may be expected to operate, and the drawbar pull test was chosen to provide a standard of comparison with existing wheel design literature. The circle and straight driving tests were each performed at different levels: for the circle driving test, the robot was driven at a constant linear speed and three different angular speeds, while for the straight driving test, the robot was driven at three different linear speeds. The data collected from these tests included the power usage from each of the wheels, measurements of the tread patterns left in the regolith surface, and the amount of slip the wheels experienced, which was calculated using data from an OptiTrack motion capture system. From the results of these experiments, we found that certain test variables were more significant than others in determining performance for each type of test, and no single wheel design clearly outperformed the others in all areas. The details of our findings will be discussed further in this paper. This data will be utilized to inform the design of the wheels for IPEx and can provide a basis for the design of wheels for future lunar terrain vehicles.

RASSOR↗