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Generation and Evaluation of Lunar Dust Adhesion Mitigating Materials

Particulate contamination is of concern in a variety of environments. This issue is especially important in confined spaces with highly controlled atmospheres such as space exploration vehicles involved in extraterrestrial surface missions. Lunar dust was a significant challenge for the Apollo astronauts and will be of greater concern for longer duration, future missions. Passive mitigation strategies, those not requiring external energy, may decrease some of these concerns, and have been investigated in this work. A myriad of approaches to modify the surface chemistry and topography of a variety of substrates was investigated. These involved generation of novel materials, photolithographic techniques, and other template approaches. Additionally, single particle and multiple particle methods to quantitatively evaluate the particle-substrate adhesion interactions were developed.

Wohl, Christopher J.↗

Evaluation of Materials and Surfaces for Lunar Regolith Adherence Characterization (RAC) Payload Samples

As the quest for long term lunar exploration and habitation comes closer to reality, widespread efforts are ongoing to effectively mitigate lunar dust surface contamination and infiltration. This dust is hazardous to humans and tends to adhere tenaciously to all exposed surfaces, causing performance issues and ultimately failure. While several active and passive technologies have been developed to address this challenge, assessing the performance of these technologies in the actual lunar environment is extremely important. The regolith adherence characterization (RAC) experiment payload provides an important opportunity for this evaluation. The RAC payload is designed by Alpha Space for the National Aeronautics and Space Administration (NASA)and scheduled to be flown to the moon in 2023 on the Firefly Aerospace Blue Ghost lander. As there were a limited number of slots available for materials to be chosen for this mission, it was critical to make an informed selection. Two polymers, a carbon fiber reinforced composite and a metal alloy were chosen to be a diverse selection of structural materials from NASA Langley Research Center. Each material was topographically modified using laser ablation patterning. This article briefly describes the selection and testing procedure and some of the results obtained for the passive dust mitigating materials and surfaces selected for this lunar surface experiment.

Lunar Dust↗

Developing Materials and Coating Technologies for Mitigation of Lunar Dust Adhesion and Abrasion

Lunar regolith was first identified as a major issue during the Apollo missions. There are three characteristics of lunar regolith that cause issues: small size, rough surface topology, and particle charge. The lack of a magnetosphere allows solar wind to bombard the lunar surface which results in the regolith becoming charged. These charged particles will adhere to most surfaces and degrade thermal control systems. The lack of atmosphere and surface liquids on the lunar surface results in the regolith’s small particle size, abrasive topology, and chemical reactivity. When the dust adheres to a surface, or the lunar lander exhaust kicks up dust regolith, it can impair instrument or thermal control system function, abrade optical surfaces, diminish range of motion, and mechanically degrade soft-goods such as gloves and astronaut suits. All of these examples were experienced during the Apollo missions. The objective of this study was to select and evaluate abrasion-resistant ceramic materials for application on the lunar landing equipment.

materials↗

Patch Plate Materials Compatibility Assessment

Lunar dust proved to be a greater problem during the Apollo missions than was originally anticipated. The highly angular, charged dust particles stuck to seals, radiators, and visors; clogged mechanisms; and abraded space suits. As reported by Apollo 12 astronaut Pete Conrad "We must have had more than a hundred hours suited work with the same equipment, and the wear was not as bad on the training suits as it is on these flight suits in just the eight hours we were out.". Dust clinging to surfaces was also transport-ed into habitable spaces leading to lung and eye irritation of the astronauts. The Apollo astronauts were on the Lunar surface less than 24 hours and experienced many dust related problems. With the Artemis program, we are planning longer stays on the surface, with more activities that have the potential to put the astronauts and equipment in contact with greater quantities of Lunar dust. The success of these missions will depend on our understanding of material interactions with Lunar dust and the development of ways to mitigate dust effects in cases where exposure to dust will lead to failure of components, unacceptable loss of power or thermal control, unacceptable loss of visibility, or health issues. Through the Lunar Surface In-novation Initiative (LSII), we are initiating a Patch Plate Materials Compatibility Assessment project. The overall goal of the three year project is to develop passive approaches to mitigate Lunar dust adhesion to surfaces for technologies that are currently at TRL levels 2-3 to bring them to TRL level 5 through ground-based assessment, culminating in a demonstration flight experiment on a Commercial Lunar Payload Services (CLPS) lander in 2022-2023. This paper discusses the detailed technical objectives and approach for this project. References: Gaier, J.R. "The Effects of Lunar Dust on EVA Systems During the Apollo Missions," NASA/TM-2005-213610/REV1, (2005), Apollo 12 Technical Crew Debriefing, December 1, 1969, pp. 10-54.

Miller, S. K. R.↗

Space Technology Mission Directorate - Game Changing Development Program: FY22 Dust Mitigation Standards Annual Review Presentation

Develop an accessible, understandable, comprehensive, and refereed guide to avoiding lunar dust problems during surface operations, both for inexperienced mechanisms designers in academia or small companies *and* for seasoned mission veterans. Extensive references into the detailed technical literature provide a “how to” lunar dust mitigation reference.

Dust Mitigation↗

Survive the Dust: Dust Mitigation Technology to Enable Survive the Night Capabilities

Introduction: As we return to the Moon, the lunar regolith (i.e. lunar dust) covering the surface will be an obstacle to nominal operations. Accounts from Apollo astronauts and analysis of hardware returned from the surface illustrate just how deleterious the dust can be [1]. During Apollo missions, the lunar dust adhered to hardware mechanically and electrostatically [2]. Surviving the Night: Mitigating the lunar dust will be critical to surviving the night. Going hand-in-hand with other extreme environment considerations, dust mitigation is critical to mission success. Dust Impacts on Other Systems: The lunar dust can have negative implications for power, thermal, mechanisms, and several other systems or sub-systems. For example, Apollo encountered marked degradation of performance in heat rejection systems for the lunar roving vehicle, science packages, and other components because of the lunar dust [1]. For power alone, dust can cause internal clogging for power connectors, heat rejection issues, excessive dust on reflective surfaces, reduced power output for solar arrays, and so on. Dust Mitigation Strategy: In addition to considering technology solutions, it is important for hardware, systems, and or components to have a dust mitigation strategy. At a high level, hardware that will encounter the lunar dust should consider these things when defining a dust mitigation strategy: • Understand Natural Environment • Understand Induced Environment • Understand Tolerance to Dust • Write Dust Requirements • Select Dust Mitigation Solutions • Test Hardware in Dusty Environment More information on each of these can be provided to hardware owners. Dust Mitigation Technology Development: NASA has a series of technologies that may be available for hardware that needs to survive the lunar night. Many of these solutions are leveraging dust mitigation technology development efforts from NASA’s Space Technology Mission Directorate (STMD), as well as efforts from ESDMD programs, industry, and academia. Through a series of STMD programs (both internal to NASA and through partnerships), there are several technologies in development as considerations as dust mitigation solutions for hardware. Within STMD, the Game Changing Development Program (GCD) has funded several internal dust mitigation projects including low to mid TRL development, demonstrations on CLPS landers of high TRL solutions, and creating standards and best practices for dust mitigation. STMD dust mitigation efforts also include a series of partnerships for developing technologies and advancing the state of dust mitigation at NASA. This includes the Lunar Surface Innovation Consortium (LSIC), Small Business Innovation Research, Early Stage Innovations (ESI), Space Technology Research Grants (STRG), Announcement of Collaboration Opportunities (ACOs) and Tipping Points (TPs), and Challenges and Crowdsourcing, among others. There are also a series of dust mitigation solutions that have been widely used terrestrially, or during Apollo. In recent years, several studies have produced more data on the efficacy of these potential solutions in the lunar environment. Dust Mitigation Solutions: Dust mitigation solutions generally fall into four categories: • Dust Tolerant Mechanisms • Passive Dust Mitigation Capabilities • Active Dust Mitigation Capabilities • Dust Measurement Capabilities There are a series of solutions that may prove beneficial for hardware that needs to survive the lunar night, including new technology development as well as proven, terrestrial solutions. This presentation will discuss in more detail what some of these solutions are for payloads going to the surface. References: [1] J. R. Gaier, NASA/TM—2005-213610, The Effects of Lunar Dust on EVA Systems During the Apollo Missions [2] T. J. Stubbs, et al. Impact of Dust on Lunar Exploration, 2005

dust mitigation↗

Dust Mitigation Technology to Enable Survive the Night Capabilities

Introduction: As we return to the Moon, the lunar regolith (i.e. lunar dust) covering the surface will be an obstacle to nominal operations. Accounts from Apollo astronauts and analysis of hardware returned from the surface illustrate just how deleterious the dust can be [1]. During Apollo missions, the lunar dust adhered to hardware mechanically and electrostatically [2]. Surviving the Night: Mitigating the lunar dust will be critical to surviving the night. Going hand-in-hand with other extreme environment considerations, dust mitigation is critical to mission success. Dust Impacts on Other Systems: The lunar dust can have negative implications for power, thermal, mechanisms, and several other systems or sub-systems. For example, Apollo encountered marked degradation of performance in heat rejection systems for the lunar roving vehicle, science packages, and other components because of the lunar dust [1]. For power alone, dust can cause internal clogging for power connectors, heat rejection issues, excessive dust on reflective surfaces, reduced power output for solar arrays, and so on. Dust Mitigation Strategy: In addition to considering technology solutions, it is important for hardware, systems, and or components to have a dust mitigation strategy. At a high level, hardware that will encounter the lunar dust should consider these things when defining a dust mitigation strategy: • Understand Natural Environment • Understand Induced Environment • Understand Tolerance to Dust • Write Dust Requirements • Select Dust Mitigation Solutions • Test Hardware in Dusty Environment More information on each of these can be provided to hardware owners. Dust Mitigation Technology Development: NASA has a series of technologies that may be available for hardware that needs to survive the lunar night. Many of these solutions are leveraging dust mitigation technology development efforts from NASA’s Space Technology Mission Directorate (STMD), as well as efforts from ESDMD programs, industry, and academia. Through a series of STMD programs (both internal to NASA and through partnerships), there are several technologies in development as considerations as dust mitigation solutions for hardware. Within STMD, the Game Changing Development Program (GCD) has funded several internal dust mitigation projects including low to mid TRL development, demonstrations on CLPS landers of high TRL solutions, and creating standards and best practices for dust mitigation. STMD dust mitigation efforts also include a series of partnerships for developing technologies and advancing the state of dust mitigation at NASA. This includes the Lunar Surface Innovation Consortium (LSIC), Small Business Innovation Research, Early Stage Innovations (ESI), Space Technology Research Grants (STRG), Announcement of Collaboration Opportunities (ACOs) and Tipping Points (TPs), and Challenges and Crowdsourcing, among others. There are also a series of dust mitigation solutions that have been widely used terrestrially, or during Apollo. In recent years, several studies have produced more data on the efficacy of these potential solutions in the lunar environment. Dust Mitigation Solutions: Dust mitigation solutions generally fall into four categories: • Dust Tolerant Mechanisms • Passive Dust Mitigation Capabilities • Active Dust Mitigation Capabilities • Dust Measurement Capabilities There are a series of solutions that may prove beneficial for hardware that needs to survive the lunar night, including new technology development as well as proven, terrestrial solutions. This presentation will discuss in more detail what some of these solutions are for payloads going to the surface. References: [1] J. R. Gaier, NASA/TM—2005-213610, The Effects of Lunar Dust on EVA Systems During the Apollo Missions [2] T. J. Stubbs, et al. Impact of Dust on Lunar Exploration, 2005

dust mitigation↗

Advancing Dust Tolerant Mechanisms for a Sustained Exploration of the Moon

Introduction: “I think dust is probably one of our greatest inhibitors to a nominal operation on the Moon. I think we can overcome other physio-logical or physical or mechanical problems except dust.”– Gene Cernan, Apollo 17 Technical Debrief The Apollo missions revealed the impact of lu-nar dust on mechanisms. Lunar dust particles are jagged and electrostatically charged, giving them the ability to bind or damage mechanisms and alter thermal properties. Reports documented clogged equipment and jammed mechanisms in every mission, regardless of surface duration, as well as clogged mechanisms in the Extravehicular Mobility Suit (EMS), including zippers, wrist and hose locks, faceplates, and sunshades [1-2]. Several astronauts remarked they could not have sustained surface activity much longer because clogged joints would have frozen up completely [2]. Effective dust mitigation strategies are need-ed to support longer duration stays on the lunar surface [3-4]. State of the Art: Technology for mechanisms able to operate in dusty enviroments is advancing rapidly due to the needs of both Mars rovers and the Artemis program. Vacuum-tight connectors are essential for spacesuits and habitats, and their performance can be dependent on cleaning technologies, which have proven difficult on the lunar surface. Several TRL 3-5 technologies are undergoing tests with the expectation to reach TRL 6 within 1-2 years. Some mechanisms will be infused and tested on the VIPER (Volatiles Inves-tigating Polar Exploration Rover) mission planned for mid-2020s. NASA Funded Efforts: NASA has recognized the need for dust tolerant mechanisms, and has partnered with industry to advance the state-of-the-art. At NASA GRC, KSC, and JSC, the Dust Tolerant Mechanisms Project is working to devel-op advanced actuator seals for rotary joints and rotary bearing technologies for long-term sus-tained operation in lunar dust environments. An-other NASA project at NASA GRC, partnered with GSFC, JPL, and KSC is Motors for Dusty & Ex-treme Cold Environments (MDECE). MDECE is developing an unheated magnetically-geared mo-tor that can operate continuously for a long dura-tion at an ambient temperature of -243 ºC (33 K). NASA GRC has the capability to characterize the effects of dust on seals, mechanisms, and other mating surfaces and components under lunar conditions [5]. Through the SBIR/STTR program, NASA has funded several companies to advance dust toler-ant mechanisms via the Dust Tolerant Mecha-nisms sub-topic with applications in surface mobil-ity, spacesuits, connectors, joints, and more. LSIC and Community Efforts: The Lunar Surface Innovation Consortium (LSIC) Dust Miti-gation focus group has fostered collaborations across NASA, industry, and academia to develop solutions that minimizes the impact of lunar dust on robotic and human systems. Community ef-forts have included topical meetings on dust tol-erant mechanisms, featured technology presenta-tions, and feedback to NASA on potential gaps and needs. Testing: In 2021, NASA released NASA-STD-1008 [6]. This NASA Technical Standard estab-lishes minimum requirements and provides guid-ance for testing systems and hardware to be ex-posed to dust in planetary environments. The standard has specific sections dedicated to Mechanisms Testing (e.g. bearings, gears) as well as Seals and Mating Surfaces Testing (e.g. hatches, docking systems). Gaps and Needs: NASA is tracking dust tol-erant mechanisms as a gap in a cross-directorate analysis of capability areas needed to enable fu-ture human space-flight architectures. Two high-priority gap areas include additional facilities for testing mechanisms in lunar-surface conditions, and a better understanding of vulnerabilities to the smallest, nanometer-scale dust particles. Conclusion: Understanding and mitigating lu-nar dust is critical to successful, sustained opera-tions on the lunar surface – whether autonomous or otherwise. This presentation will discuss both the state-of-the-art and open needs in lunar dust tolerant mechanisms, technology impacts, mitiga-tion approaches, testing, LSIC community efforts, and more. References: [1] Gaier, J. R. (2020). The Im-pact of Dust on Lunar Surface Equipment During Apollo. Lunar Dust 2020. [2] GRC, & Gaier, J. R. (2005). The Effects of Lunar Dust on EVA Sys-tems During the Apollo Missions. [3] Johansen, M. R. (2020). An Update on NASA’s Lunar Dust Mitigation Strategy. Lunar Dust 2020. [4] ASI, CSA, ESA, JAXA, & NASA. (2016). Dust Mitiga-tion Gap Assessment Report. [5] Jimenez, N. et al (2022), LPSC Abstract 2572. [6] NASA-STD-1008, 2021.

J I Nunez↗

System concepts for a large UV/optical/IR telescope on the moon

To assess the systems and technological requirements for constructing lunar telescopes in conjunction with the buildup of a lunar base for scientific exploration and as a waypoint for travel to Mars, the NASA Marshall Space Flight Center conducted concept studies of a 16-m-aperture large lunar telescope (LLT) and a 4-m-aperture precursor telescope, both operating in the UV/visible/IR spectral region. The feasibility of constructing a large telescope on the lunar surface is assessed, and its systems and subsystems are analyzed. Telescope site selection, environmental effects, and launch and assembly scenarios are also evaluated. It is argued that key technical drivers for the LLT must be tested in situ by precursor telescopes to evaluate such areas as the operations and long-term reliability of active optics, radiation protection of instruments, lunar dust mitigation, and thermal shielding of the telescope systems. For a manned lunar outpost or an LLT to become a reality, a low-cost dependable transportation system must be developed.

Nein, Max E.↗

Engineering the Interface: Advanced Surface Technologies for Lunar Dust Management and Equipment Longevity

Through the Artemis program, NASA intends to develop a sustainable human foothold on the Moon, ultimately paving the way for crewed exploration of Mars. The Moon's hostile environment poses numerous obstacles, including exposure to radiation, temperature extremes, micrometeoroid threats, and particularly the persistent problem of lunar dust. Lunar dust impacts nearly every aspect of surface operations through adhesion and abrasion mechanisms, with contamination from anthropogenic activities (landing, rovers) far outweighing natural phenomena. Multiple adhesion pathways contribute to surface contamination in the lunar environment, including van der Waals forces, electrostatic forces, chemical reaction, and magnetic forces from elemental iron deposits. Sharp asperities from micrometeoroid bombardment and atmospheric absence increase interaction potential and enable mechanical interlocking. Low cohesion between dust particles exacerbates these challenges, as minimal interaction potential between dust and nearby surfaces overcomes particle cohesion, causing contamination. Lunar dust adhesion mitigation technologies can be categorized as either active, requiring external energy, or passive, relying on intrinsic material properties. Ultrasonic and electrodynamic technologies have been developed to the highest technology readiness level for active approaches. Passive strategies primarily focus on surface chemistry and topography modifications. At NASA Langley Research Center, approaches include surface migration agents to reduce surface energy, topographical modification using laser ablation patterning, and tailored surface conductivity to reduce intrinsic adhesion force. Performance has been evaluated using custom-built ultrasonic and centrifuge instruments. Plume-surface interactions from lunar landers can propel micrometer-sized particles at velocities up to 1000 m s-1.8 These particles pose risks to landers, habitats and infrastructure, leading to erosion, degradation, and reduced component lifespan. A panel recovered from Surveyor III was determined to have been severely abraded because of lunar dust displaced from the Apollo 12 lunar module that landed 160 m away. The performance of metallic surfaces has been evaluated via high velocity single particle impact using the laser-induced project impact test (LIPIT) facility at the University of Utah. Peridynamics modeling, a form of continuum mechanics that uses a nonlocal approach enabling greater simulation capabilities of crack initiation and fracture, has also been utilized to gain greater insight into material response during impact events. Lunar dust contamination challenges extend to power generation systems and moving equipment. Cables, rotation stages, and other mechanisms may experience limited range of motion and reduced lifetime due to dust infiltration. NASA Langley Research Center has evaluated traditional aerospace alloys, softgoods, wear resistant ceramics, and several polymer and polymer composite materials. Test methods have included traditional techniques like Taber abrasion testing, as well as designed test configurations developed in the DUSTE (dust, ultraviolet radiation, and space thermal environmental) chamber that reproduce mechanism functions in operational environment. Beyond laboratory experiments, several flight experiments have been conducted. Materials were exposed to the low Earth orbit environment on the Materials International Space Station Experiment (MISSE) and to the lunar surface environment through the Aegis Aerospace Regolith Adherence Characterization (RAC) payload and the Honeybee Robotics PlanetVac payload. Determining lunar dust's impact on surface exploration and habitation requires comprehensive experimental and computational capabilities combined with lessons learned from initial lunar activities. Identifying the greatest environmental challenges and developing mitigation technologies provides the clearest path toward successfully, expeditiously, and efficaciously completing NASA's mission. This presentation will discuss ongoing efforts at NASA Langley Research Center and collaborator contributions to these critical objectives.

Surface Engineering↗

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.↗

Overview of Materials International Space Station Experiment 7B

Materials International Space Station Experiment 7B (MISSE 7B) is the most recent in a series of experiments flown on the exterior of International Space Station for the purpose of determining the durability of materials and components in the space environment. A collaborative effort among the Department of Defense, the National Aeronautics and Space Administration, industry, and academia, MISSE 7B will be flying a number of NASA experiments designed to gain knowledge in the area of space environmental effects to mitigate risk for exploration missions. Consisting of trays called Passive Experiment Containers, the suitcase sized payload opens on hinges and allows active and passive experiments contained within to be exposed to the ram and wake or zenith and nadir directions in low Earth orbit, in essence, providing a test bed for atomic oxygen exposure, ultraviolet radiation exposure, charged particle radiation exposure, and thermal cycling. New for MISSE 7B is the ability to monitor experiments actively, with data sent back to Earth via International Space Station communications. NASA?s active and passive experiments cover a range of interest for the Agency. Materials relevant to the Constellation Program include: solar array materials, seal materials, and thermal protection system materials. Materials relevant to the Exploration Technology Development Program include: fabrics for spacesuits, materials for lunar dust mitigation, and new thermal control coatings. Sensors and components on MISSE 7B include: atomic oxygen fluence monitors, ultraviolet radiation sensors, and electro-optical components. In addition, fundamental space environmental durability science experiments are being flown to gather atomic oxygen erosion data and thin film polymer mechanical and optical property data relevant to lunar lander insulation and the James Web Space Telescope. This paper will present an overview of the NASA experiments to be flown on MISSE 7B, along with a summary of the thermal environment to be expected during the 1 yr mission scheduled for launch in 2009.

Jaworske, Donald A.↗

Idea Evolution ... What's Next?

No research project lasts forever. Even the most wildly successful programs will eventually come to an end. The challenge in that moment, when a project ends, is how to take what was learned in that project and apply it to the next research activity you undertake. Although not always possible, information and insights from a project that is underway or coming to a close can be leveraged to identify a new research direction and advance existing tangentially related activities. In this presentation, a common thread will be followed through a series of sequential research projects where lessons learned in each activity were built into the next enabling each new research project to advance further and faster. Initial research focused on lunar dust adhesion mitigation coalesced into two major contributors to adhesion interactions; which were, not surprisingly, surface chemistry and topography. This knowledge was applied to addressing insect residue adhesion mitigation on commercial aircraft leading edge surfaces. Composite epoxy coatings formulated with controlled surface chemistry and topography were evaluated and led to identification of additional relevant considerations: dynamics and surface morphology. Collectively, these considerations were applied to address impact ice adhesion mitigation where further properties were elucidated: surface mechanical properties and durability. Seeking commonality between these research endeavors led to greater understanding of each new research objective and ultimately, identification of robust, viable pathways toward meaningful results.

Adhesion Mitigation↗

NASA LSII Lunar Simulant Project

Introduction: America has entered a new era of exploration. NASA’s Artemis program will lead humanity forward to the Moon and prepare us for the next giant leap, the exploration of Mars [1]. To champion technologies needed to live on and explore the Moon, NASA’s Space Technology Mission Directorate (STMD) established the Lunar Surface Innovation Initiative (LSII)[2].LSII's technology development portfolio includes: Utilizing the Moon’s resources; Establishing sustainable surface power; Building machinery and electronics that work in extreme environments, like super-chilly permanently shadowed craters; Mitigating lunar dust; Carrying out surface excavation, manufacturing and construction duties; and Extreme access which includes navigating and exploring the surface/subsurface. To support the development and testing of these technologies, LSII created the lunar simulant project, to create and/or acquire low-, medium-and high-fidelity lunar simulants to match the needs of STMD projects at all levels of technology readiness levels (TRL), as well as other NASA programs. There is not one bulk lunar simulant that will satisfy the needs of all projects. NASA's Approach to Simulants: Just as LSII's activities are being implemented through a combination of unique NASA work and public-private partnerships, NASA will work with commercial simulant providers to acquire simulants that meet NASA's needs. If warranted, NASA will develop simulants using government agencies, as was done with the NASA/USGS Lunar Highlands Type (NU-LHT)series of lunar simulants [3].NASA is also collaborating with the Johns Hopkins University Applied Physics Laboratory(JHUAPL) Lunar Surface Innovation Consortium (LSIC) in the development and characterization of lunar simulants [4]. Within NASA, a small team (< 10 people) is coordinating simulant activities across the agency, with team members located at several NASA centers. The overall objective of the project is to procure lunar simulants in sufficient amounts for earth-based testing of subsystems and systems in a variety of environments (i.e., laboratory, high-bay, thermal-vacuum chambers), required for Artemis missions to the Moon, as well as other missions carrying NASA lunar payloads, such as the Commercial Lunar Payload Services (CLPS)program [5]. Lunar Highlands Simulant: NASA's Artemis Program is targeting the lunar south pole region for initial human missions and the Artemis Base Camp. Hence, the LSII lunar simulant project is currently focusing on the mineralogy and properties of lunar highlands regolith [6 and 7]. Plagioclase-rich rocks (e.g., anorthosite, norite) are the dominant constituent in highlands simulants, with Shawmere, Stillwater, and White Mountain anorthosites being used in commercially available simulants. However, because these feedstocks are terrestrial in nature, they include hydrated minerals, carbon-bearing minerals, and other chemical signatures that are not present on the Moon, and these minor mineral assemblages need to be taken into account when trying to understand test procedures and results. Glass Component: While much attention has been placed on the rock/mineral component of lunar simulants, glass is just as important when creating simulants. The glass component in lunar regoliths is often greater than 50% by volume [8]. This component includes impact melt glass, dark matrix breccias, and agglutinates. However, this component is difficult, time-consuming and expensive to make. Most lunar simulants, past and current, have relied on basaltic cinder as a feedstock for glass. Getting better glass components at a lower cost, particularly agglutinates and glass with an anorthositic composition is a near-term objective that the NASA simulant project is trying to address . Characterization: It is extremely important for lunar simulants to be characterized by several analytical methods. Gruener et al. [9] and JHUAPL LSIC [10] conducted initial assessments of some of the commercially available simulants in 2019 and early 2020, before the global pandemic. Further analyses are needed to better quantify important parameters such as, modal mineralogy and glass content, particle shape, and particle size distribution. These quantified results can then be used in determining figures of merit (FOM) that show how well simulants compare to lunar regolith [11 and 12].

J E Gruener↗