Thermal properties of postulated lunar surface materials.
Thermal conductivity of simulated lunar surface materials
TEMPERATURE MEASUREMENT↗
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An experimental study of fluidization processes under lunar conditions
Fluidized ash flow in simulated lunar soils
FLUIDIZED BED↗
Regolith-structure modeling
Early lunar missions have provided a basic understanding of the physical and strength properties of lunar regolith, which have been shown to differ from those of dry terrestrial granular soils. Lunar regolith is predominantly a fine sand of which nearly 40 percent can be characterized as silt with a particle size smaller than 100 micrometers. The top 10 to 20 cm of the regolith can be characterized as being in a loose to medium-loose state. The density of the regolith, however, rapidly increases below a depth of 20 cm. The highly irregular and angular shapes of the regolith particles tend to interlock and create relatively strong mechanical bonds that give the particulate mass substantial cohesive properties and smaller amounts of tensile strength properties. In addition, the friction angle of lunar regolith at medium to high densities is quite high and often exceeds 55 degrees. These known properties of lunar regolith have been matched in a terrestrially-manufactured analog known as Minnesota Lunar Simulant. A variety of experiments were conducted using this simulant to both verify existing information and generate new information on the physical and constitutive properties of lunar regolith. These experiments include maximum and minimum density determinations, specific mass of solids, grain-size distribution, conventional triaxial compression and extension, isotropic compression, one-dimensional compression, direct shear, and direct tension. Direct shear experiments were conducted under atmospheric and vacuum conditions. Results of the physical and strength experiments compare closely to results obtained from lunar missions. Results of simulant strength experiments performed in vacuum indicated no observable difference from results obtained in air. A test bed currently under study is one involving a regolith shield covering a first-generation human habitat module. It is understood that regolith in depths ranging from 3 to 5 meters is required for radiation shielding for habitation and workspace. The habitat module is treated as a rigid cylindrical tube with a smooth exterior. By making the cylinder rigid, a complex interaction problem is reduced to a situation where we can consider the support regolith and the shielding regolith as behaving independently of the structural properties of the cylindrical structure. Medium-dense lunar simulant was placed around a scaled model of the habitat module to provide a radiation shield. This embankment-type shield was constructed in relatively thin but fine layers by compacting, by mechanical vibratory means, layer upon layer of simulant placed adjacent to the horizontally-aligned cylinder. The slope angles were constructed at 55 degrees. The model described above was studied in a geotechnical centrifuge, which allows for the scaling of model dimensions to prototype dimensions by increasing the acceleration of gravity on the model. The deformation response can be scaled up to prototype dimensions to provide an assessment of the deformation patterns of the lunar structure. The actual process of local and/or global growth of instabilities or skip planes can also be observed.
Ko, Hon-Yim↗
Lunar Development & Test Facility, JSC B351
In anticipation of extended operations on the lunar sur-face, JSC Building B351 has been prepared to meet test needs to mature technologies that extract resources from lunar regolith, handle lunar regolith or must perform in a dusty lunar environment. Domains such as In-Situ Re-source Utilization (ISRU), dust mitigation, power generation and distribution, robotics and surface tools will all require testing with lunar regolith/simulants to demonstrate flight readiness. The Lunar Development and Test Facility (LDTF) houses environmental test capabilities, including lunar simulants, geared toward advancing Technical Readiness Level (TRL) of these lunar surface technologies. Seen as an agency need to enable and demonstrate new technologies, a portion of the facility capability was developed under the “Dirty Lunar Surface Simulation “project in FY2020, funded by the NASA Game Changing Development program. Some current uses include testing of an oxygen extraction from lunar regolith test, a spacesuit cleaning tool evaluation, and a study to measure dust effects on space radiators (thermal management).
Michael Reddington↗
Synthesis and Stability of Iron Nanoparticles for Lunar Environment Studies
Simulant of lunar dust is needed when researching the lunar environment. However, unlike the true lunar dust, today s simulants do not contain nanophase iron. Two different processes have been developed to fabricate nanophase iron to be used as part of the lunar dust simulant: (1) Sequentially treating a mixture of ferric chloride, fluorinated carbon, and soda lime glass beads at about 300 C in nitrogen, at room temperature in air, and then at 1050 C in nitrogen. The product includes glass beads that are grey in color, can be attracted by a magnet, and contain alpha-iron nanoparticles (which seem to slowly lose their lattice structure in ambient air during a period of 12 months). This product may have some similarity to the lunar glassy regolith that contains Fe(sup 0). (2) Heating a mixture of carbon black and a lunar simulant (a mixed metal oxide that includes iron oxide) at 1050 C in nitrogen. This process simulates lunar dust reaction to the carbon in a micrometeorite at the time of impact. The product contains a chemically modified simulant that can be attracted by a magnet and has a surface layer whose iron concentration increased during the reaction. The iron was found to be alpha-iron and Fe3O4 nanoparticles, which appear to grow after the fabrication process, but stabilizes after 6 months of ambient air storage.
Hung, Ching-cheh↗
A borehole jack for deformability, strength, and stress measurements in a 2-inch borehole
A borehole jack devised for lunar exploration is described and results of its use in simulated lunar solids are presented. A hydraulic cylinder mounted between two stiff plates acts to spread the plates apart against the borehole walls when pressured. The spreading is measured by a displacement transducer and the load is measured hydraulically. The main improvement over previous instruments is the increased stroke, which allows large deformations of the borehole. Twenty-eight pistons are used to obtain a high hydraulic efficiency, and three return pistons are also provided. Pressure-deformation curves were obtained for each test on Lunar Soil Simulant No. 2, a light gray silty basalt powder.
Goodman, R. E.↗
Lunar regolith densification
Core tube samples of the lunar regolith obtained during the Apollo missions showed a rapid increase in the density of the regolith with depth. Various hypotheses have been proposed for the possible cause of this phenomenon, including the densification of the loose regolith material by repeated shaking from the seismic tremors which have been found to occur at regular monthly intervals when the moon and earth are closest to one another. A test bed was designed to study regolith densification. This test bed uses Minnesota Lunar Simulant (MLS) to conduct shaking experiments in the geotechnical centrifuge with an inflight shake table system. By reproducing realistic in-situ regolith properties, the experiment also serves to test penetrator concepts. The shake table system was designed and used for simulation experiments to study effects of earthquakes on terrestrial soil structures. It is mounted on a 15 g-ton geotechnical centrifuge in which the self-weight induced stresses are replicated by testing an n-th scale model in a gravity field which is n times larger than Earth's gravity. A similar concept applies when dealing with lunar prototypes, where the gravity ratio required for proper simulation of lunar gravity effects is that between the centrifugal acceleration and the lunar gravity. Records of lunar seismic tremors, or moonquakes, were obtained. While these records are being prepared for use as the input data to drive the shake table system, records from the El Centro earthquake of 1940 are being used to perform preliminary tests, using a soil container which was previously used for earthquake studies. This container has a laminar construction, with the layers free to slide on each other, so that the soil motion during the simulated earthquake will not be constrained by the otherwise rigid boundaries. The soil model is prepared by pluviating the MLS from a hopper into the laminar container to a depth of 6 in. The container is mounted on the shake table and the centrifuge is operated to generate an acceleration of 10 times Earth's gravity or 60 times the lunar gravity, thus simulating a lunar regolith thickness of 30 ft. The shake table is then operated using the scaled 'moonquake' as the input motion. One or more model moonquakes are used in each experiment, after which the soil is analyzed for its density profile with depth. This is accomplished by removing from the soil bed a column of soil contained within a thin rubber sleeve which has been previously embedded vertically in the soil during pluviation. This column of soil is transferred to a gamma ray device, in which the gamma ray transmission transversely through the soil is measured and compared with standard calibration samples. In this manner, the density profile can be determined. Preliminary results to date are encouraging, and the Center plans to study the effects of duration of shaking, intensity of the shaking motion, and the frequency of the motion.
Ko, Hon-Yim↗
Ultrasonic modeling of lunar approach of the lunar excursion module
Ultrasonic modeling system for simulating lunar excursion module landing trajectory on lunar surface
LUNAR EXCURSION MODULE /LEM/↗
Exploratory study of man's self-locomotion capabilities with a space suit in lunar gravity
Human performance in pressurized suit in simulated lunar gravity environment compared to performance in earth gravity
EARTH↗
An Evidence-based Approach to Developing a Management Strategy for Medical Contingencies on the Lunar Surface: The NASA/Haughton-Mars Project (HMP) 2006 Lunar Medical Contingency Simulation at Devon Island
The lunar architecture for future sortie and outpost missions will require humans to serve on the lunar surface considerably longer than the Apollo moon missions. Although the Apollo crewmembers sustained few injuries during their brief lunar surface activity, injuries did occur and are a concern for the longer lunar stays. Interestingly, lunar medical contingency plans were not developed during Apollo. In order to develop an evidence-base for handling a medical contingency on the lunar surface, a simulation using the moon-Mars analog environment at Devon Island, Nunavut, high Canadian Arctic was conducted. Objectives of this study included developing an effective management strategy for dealing with an incapacitated crewmember on the lunar surface, establishing audio/visual and biomedical data connectivity to multiple centers, testing rescue/extraction hardware and procedures, and evaluating in suit increased oxygen consumption. Methods: A review of the Apollo lunar surface activities and personal communications with Apollo lunar crewmembers provided the knowledge base of plausible scenarios that could potentially injure an astronaut during a lunar extravehicular activity (EVA). Objectives were established to demonstrate stabilization and transfer of an injured crewmember and communication with ground controllers at multiple mission control centers. Results: The project objectives were successfully achieved during the simulation. Among these objectives were extraction from a sloped terrain by a two-member crew in a 1 g analog environment, establishing real-time communication to multiple centers, providing biomedical data to flight controllers and crewmembers, and establishing a medical diagnosis and treatment plan from a remote site. Discussion: The simulation provided evidence for the types of equipment and methods for performing extraction of an injured crewmember from a sloped terrain. Additionally, the necessary communications infrastructure to connect multiple centers worldwide was established from a remote site. The surface crewmembers were confronted with a number of unexpected scenarios including environmental, communications, EVA suit, and navigation challenges during the course of the simulation which provided insight into the challenges of carrying out a medical contingency in an austere environment. The knowledge gained from completing the objectives will be incorporated into the exploration medical requirements involving an incapacitated astronaut on the lunar surface.
Scheuring, R. A.↗
Materials Requirements for Standard Lunar Highlands Regolith Simulants as Defined by the NASA Simulant Development Program
The development of surface technologies for NASA's human and robotic lunar program beyond 2010 has begun. The multitude of projects underway and future ones will soon rely on the availability of lunar regolith simulant materials chosen to simulate the characteristics of lunar regoliths in order to design, test and qualify prototype hardware and flight equipment. The selection and development of standard lunar regolith simulants (SLRS) for the use of NASA technology programs was one of the main recommendations of the 2005 Workshop on Lunar Regolith Simulant Materials at Marshall Space Flight Center. The realization of that objective is now underway through the NASA simulant development program at the Marshall Space Flight Center. The approach adopted to define materials requirements for standard simulants of regolith from the Highlands regions of the Moon will be presented along with a discussion of limitations inherent to such an endeavor.
Sibille, Laurent↗
HERA in the Artemis ERA
As NASA shifts its mission objectives to the lunar surface and the return of humans to the moon in the next few years, analogs that simulate lunar transit or surface exploration are in a unique position to support spaceflight research that is aligned with future Artemis missions, especially a sustained lunar presence. NASA’s spaceflight analogs have historically focused on mission scenarios and operations for Mars exploration, including recent campaigns staged at the Human Exploration Research Analog (HERA) analog at Johnson Space Center. However, beginning in Campaign 8, future HERA missions are planned to mimic lunar operations and support research objectives that directly address knowledge gaps for lunar exploration and habitation. The Research Operations and Integration (ROI) HERA team will present a look-back over HERA mission scenarios and operations supporting NASA’s Human Research Program and international partners’ spaceflight research. An overview of critical capabilities in HERA and other similar analogs will also be presented, such as methods of simulating EVAs. Presenters will then discuss the transition to a high-fidelity lunar surface exploration mission scenario envisioned for Campaign 8, slated to begin in 2026. Operations changes that will be discussed will include simulated lunar surface exploration using a two-person simulated pressurized rover in combination with virtual reality, lunar-relevant communication delays, changes to concepts of how crew communicate with Earth-based mission supports, increased access to family & friends’ communication compared to prior campaigns, and a new mission scenario referencing Artemis mission objectives and tasks. ROI analog mission designs are driven by science objectives. The ROI HERA team will describe how the changes for Campaign 8 support ongoing spaceflight research interests and provide opportunities for investigators to design experiments more closely aligned to lunar missions. A questions and answers session will follow with attendees encouraged to ask questions.
B J Caldwell↗
Lunabotics Robotic Mining Competition for Universities
Space Mining for resources such as water ice, and regolith, which contain many elements in the form of metals, minerals, volatiles and other compounds, is a necessary step for In-Situ Space Resource Utilization (ISRU). One of the primary goals is to extract propellants from the regolith and water ice, such as oxygen and hydrogen which could then be used for in-space transportation. In addition, the space mining system can be used for various construction tasks that can benefit human and robotic exploration as well as scientific investigations based on excavated exposed topography, such as the side walls of trenches. The National Aeronautics & Space Administration (NASA) “Lunabotics” Robotic Mining Competition (RMC) is a university-level competition designed to engage and retain students in science, technology, engineering and mathematics (STEM). NASA has directly benefited from the competition by encouraging the development of innovative lunar excavation concepts from universities which has resulted in clever ideas and solutions which could be applied to an actual lunar excavation device or payload. The challenge is for students to design and build a remote controlled or autonomous 80 kg mass lightweight excavator, called a “lunabot”, which can collect and deposit a minimum of 10 kilograms of lunar simulant within 15 minutes. In recent years the goal has been changed to excavate a minimum of 1 kg of simulated icy regolith which is found under an overburden of regolith simulant. The complexities of the challenge include the abrasive characteristics of the lunar regolith simulant, the weight and size limitations of the lunabot, and the ability to control the lunabot from a remote mission control center or operate it autonomously. This presentation will summarize the results of the Lunabotics Robotic Mining Competitions held in May 2022. Each year, since 2010, over 50 university teams have attended, resulting in over 500 lunabot designs and subsequent prototypes. Over 6,000 university students have been part of the on-site competition at KSC, and many are employed in the space sector today with thriving careers. Even more students and the public were engaged via internet broadcasting and social networking media. Examples of how this translates to hiring opportunities for commercial sponsors will also be discussed. Overall, this competition has proven to be popular with multi-disciplinary university senior design classes and a valuable tool for NASA and academia in educating and inspiring the next generation of space engineers.
Lunabotics↗
Moonwalking: Physical Simulation of the Lunar South Pole Lighting Environment
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Lunar↗
The effects of lunar gravity on metabolic rates
Effects of simulated lunar gravity on metabolic rates while wearing pressure suits
Robertson, W. G.↗
Thermal infrared spectra of the Moon
Contrary to recent assertions in the literature, lunar emission spectra obtained at an altitude of 32 km with a balloon-borne telescope are virtually undistorted by atmospheric absorption, except in the ozone region. These spectra have been found to correlate closely with laboratory emission spectra of returned lunar samples measured in a simulated lunar environment. Thus, lunar spectra obtained with the balloon-borne telescope system are the standards against which groundbased spectral measurements of the Moon should be compared. Comparison of balloon-borne measurements with recent groundbased spectral measurements suggests that the latter suffer from some source of systematic error. When high-quality lunar spectra are available, they will be best interpreted by comparison with returned lunar samples, rather than terrestrial minerals or rocks, because of subtle spectral differences between lunar and terrestrial minerals perhaps associated with incipient alteration of the latter.
Salisbury, John W.↗
Millimeter Wave Doppler Radar Testing Using the Lunar Regolith Ejecta Simulator
A linear conveyor system has been devised to maintain lunar regolith simulant at a range of velocities, distances, angles, particle densities, and particle sizes. The Lunar Regolith Ejecta Simulator (LuRES) system shall test prototype and potential flight instrumentation for measuring the velocities of regolith particles accelerated by a plume-surface interaction (PSI) and determining effects of particle number densities and particle size distributions on return signals. Here we present the results of initial LuRES testing of the Millimeter Wave Doppler Radar (MWDR) instrument. The LuRES system held a single, ~900 µm BP-1 lunar regolith simulant particle at a continuous ~5 m/s velocity. The return signal of the MWDR from this LuRES configuration was analyzed to calibrate the MWDR instrument. Further testing is planned for the remaining of 2023 to calibrate the MWDR for various particle sizes and densities at a continuous velocity. These results will be presented in the final paper.
PSI↗
Constraining Particle Variation in Lunar Regolith for Simulant Design
Simulants are used by the lunar engineering community to develop and test technologies for In Situ Resource Utilization (ISRU), excavation and drilling, and for mitigation of hazards to machinery and human health. Working with the United States Geological Survey (USGS), other NASA centers, private industry and academia, Marshall Space Flight Center (MSFC) is leading NASA s lunar regolith simulant program. There are two main efforts: simulant production and simulant evaluation. This work requires a highly detailed understanding of regolith particle type, size, and shape distribution, and of bulk density. The project has developed Figure of Merit (FoM) algorithms to quantitatively compare these characteristics between two materials. The FoM can be used to compare two lunar regolith samples, regolith to simulant, or two parcels of simulant. In work presented here, we use the FoM algorithm to examine the variance of particle type in Apollo 16 highlands regolith core and surface samples. For this analysis we have used internally consistent particle type data for the 90-150 m fraction of Apollo core 64001/64002 from station 4, core 60009/60010 from station 10, and surface samples from various Apollo 16 stations. We calculate mean modal compositions for each core and for the group of surface samples and quantitatively compare samples of each group to its mean as a measurement of within-group variance; we also calculate an FoM for every sample against the mean composition of 64001/64002. This gives variation with depth at two locations and between Apollo 16 stations. Of the tested groups, core 60009/60010 has the highest internal variance with an average FoM score of 0.76 and core 64001/64002 has the lowest with an average FoM of 0.92. The surface samples have a low but intermediate internal variance with an average FoM of 0.79. FoM s calculated against the 64001/64002 mean reference composition range from 0.79-0.97 for 64001/64002, from 0.41-0.91 for 60009/60010, and from 0.54-0.93 for the surface samples. Six samples fall below 0.70, and they are also the least mature (i.e., have the lowest I(sub s)/FeO). Because agglutinates are the dominant particle type and the agglutinate population increases with sample maturity (I(sub s)/FeO), the maturity of the sample relative to the reference is a prime determinant of the particle type FoM score within these highland samples.
Schrader, Christian M.↗