Dust Testing
Dust testing splits into four separate problems with separate rigs: how much dust is on the surface and how it got there, how the dust wears material away, whether the dust gets past a seal into a bearing, and whether an active removal system works. Nine dust-caused hazards were identified from Apollo experience: obscured vision, clogged equipment, coated surfaces, loss of surface traction, inhaled dust, degraded radiators, fooled instruments, failed seals, and abrasion [1].
Applying the dust
Section titled “Applying the dust”An abrasion or coverage result is only as repeatable as the deposition. The Uniform Dust Deposition System at Glenn deposits simulant on test articles up to 60 cm in diameter and 15 cm high, in dry air below 1 percent relative humidity, with the operator isolated from aerosolized dust [2]. An imaging subsystem counts particles and measures size by machine learning, predicting surface deposition density from images alone at a coefficient of determination of 0.93, and coverage uniformity reaches a coefficient of variation below 0.11.
Single-run accuracy is the weak point: standard deviation of 18 to 24 mg, or 0.839 to 1.184 mg/cm2, over a 5 cm diameter area [2]. Building the deposit up over multiple runs tightens this to 0.2 to 0.6 mg, or 0.076 to 0.227 mg/cm2, over the same area [2].
Abrasion
Section titled “Abrasion”Two-body scratch testing establishes the volumetric wear measurement from a single particle on a flat surface. Three-body testing is closer to the lunar case: a rotating rubber wheel loads a specimen while loose abrasive is fed into the contact, following ASTM B611 but with the water omitted. Mass loss is converted to wear volume through the specimen density [3].
Abrasives and specimens run in that campaign, and the result that matters for simulant selection:
| Abrasive | Note |
|---|---|
| JSC-1A-F, nominal size distribution | Consistently more abrasive than the sieved version of the same simulant |
| JSC-1A-F sieved below 25 um | Less abrasive than nominal |
| NU-LHT-2M | Lunar highland simulant |
| Alumina, 50 um average, per ASTM G76 | Dominated the abrasion; not representative of lunar dust |
| Silica, 50/70 mesh, per ASTM G65 | Simulants resembled silica sand only on the softer specimens, aluminum and PMMA |
Source: [3].
Specimens were PMMA, hardened 1045 steel, 6061-T6 aluminum and 1018 steel; the simulants abraded all of them [3].
The grain size result is repeated in fabric testing. Abrasion of Orthofabric, the outer layer of the Apollo suit, is more likely with larger grains than with the finest fraction, measured across a tumbler method, the Martindale method and an Accelerotor [4]. Ceramic coatings are tested against the same problem: air plasma sprayed alumina and 8 wt percent yttria-stabilized zirconia were compared by mass loss at intervals, surface roughness by profilometer, and microscopy, with alumina showing better wear resistance than 8YSZ, though 8YSZ remains attractive because it can be tailored. That campaign also established that the choice of wear medium has a distinct effect on the abrasion result, so the medium is a test variable rather than a background condition [5].
Textile screening for the VIPER mobility barrier used a Martindale abrasion test with a 150-grit garnet abradant at a 1 psi (6.89 kPa) load on a 1 inch (2.54 cm) plate for 10,500 cycles, with the abradant replaced every 10 percent of the test [6]. Garnet at 6.5 to 7.5 on the Mohs scale was chosen to match the upper range of JSC-1A. Evaluation covered air permeation, thickness and weight after wear cycles, flexibility and visual wear. The baseline air permeation of 22.5 cfm (38.23 m3/h) let all sizes of JSC-1A pass freely, which is what a candidate barrier has to beat [6].
Seals and bearings
Section titled “Seals and bearings”Bearings are the mechanism elements most prone to failure from dust intrusion, which is why the sealing effort concentrates on them, and the seal materials themselves degrade: a spring-energized PTFE seal is damaged faster by larger particles, so it is placed last in a series behind coarser barriers [6]. Bushings carry a lower risk of failure from dust intrusion than bearings, and self-lubricating Vespel SP-3 bushings are used at pin joints for that reason, since a wet-lubricated joint attracts particulate.
The VIPER mobility system stacked four barrier types in series, in order of decreasing particle size admitted :
| Barrier | Function and sizing |
|---|---|
| Global softgoods barrier (“Sock”) | Kevlar with integrated MLI over the whole mobility appendage; Nomex woven textile with a 0.5 inch (1.2 cm) graphite grid for surface resistivity; must survive thousands of motion cycles |
| Labyrinth | Coarse rejection of gravel-sized clasts; gaps sized by manufacturability at about 0.76 mm radial and 1.00 to 1.27 mm axial; three full teeth on the best-oriented application |
| Nomex felt, face or radial | Fine debris; face seals at 20 percent compression of seal thickness, from MER and MSL experience, against 5 to 10 percent suggested by Tri-ATHLETE |
| Spring-energized PTFE | Finest particles, placed last in the series because larger particles damage PTFE; rides on a surface held to Ra 0.8 um, lubricated with Braycote 600 |
Source: [6].
Grease damming at tight shaft clearances is used as a fifth, informal barrier, and on the suspension load cell bearing, where drag torque does not matter because motion is minimal, a deliberately thick grease application is the primary mitigation.
Radial seals are sized against parasitic torque: interference is swept while torque is measured at ambient and then at the actuator temperature extremes using an oven and chiller at ambient pressure, and drag torque is tracked at every seal interface against the actuator torque margin.
System-level dust exposure testing
Section titled “System-level dust exposure testing”The VIPER dust box held a mobility module inside a global seal with 1419 g of JSC-1A agitated by two fans every hour, with the drive, steering and suspension actuators sweeping continuously for 57 hours and 35 minutes, representing about 10 km of early mission traverse [6]. Current draw and internal temperatures stayed nominal; on teardown no measurable simulant was found inside the barrier or on internal hardware, and the mylar layers at high-flexion locations were undamaged [6].
Deposition on the article inside such a chamber is not uniform unless it is made so, which is the reason for a separate deposition standard [2].
Wheel-to-barrier interference was life tested separately at ambient for 40 km equivalent travel, about twice expected mission life, by cycling the mechanisms through full range of motion at the greatest inducible interference [6]. The germanium outer coating wore visibly, including at seams the wheel could not have touched; the Kevlar showed only minor stretching. The flight units delete the germanium coating in the interference regions as a result [6].
Active removal
Section titled “Active removal”The Electrodynamic Dust Shield is a substrate carrying interdigitated electrodes driven with out-of-phase high voltage pulses, producing a traveling electrodynamic wave that moves adherent dust off the surface by the dielectrophoretic force. It has been tested in vacuum chambers with lunar simulants and with Apollo regolith samples, and on reduced gravity flights that combine lunar gravity with vacuum. Twelve panels of glass, polyimide and prototype spacesuit fabric, some with a lotus leaf coating and some with thermal paint, flew on MISSE-11 in the wake position of the ISS for one year: two were energized and returned current and voltage data against a ground baseline, the remaining ten were passive and were to be operated in a vacuum chamber after return, and all twelve were imaged monthly to track change with time. Preflight ground testing on non-flight panels covered vibration and thermal vacuum, and early thermal runs failed by electrical breakdown across debonded surfaces before the final panels cleared dust nominally both before and after thermal testing [8].
The Apollo brushing precedent
Section titled “The Apollo brushing precedent”A pre-mission study using soil returned from Apollo 12 concluded that a nylon bristle brush would remove lunar soil and dust effectively. Brushing was used on the Lunar Roving Vehicle radiators during Apollo 15, 16 and 17 and was almost wholly ineffective: the brush did not remove the finest particles and radiator thermal performance degraded despite it [7]. Re-testing the same technology under simulated lunar conditions found that two brushes, a Zephyr fiberglass fingerprint brush and an Escoda nylon fan brush, removed over 90 percent of the dust from AZ93 and aluminized FEP and recovered 80 percent or more of the original solar absorptance to emittance ratio after 20 strokes and 90 percent or more after 200 strokes. Absolute brush performance depends on which simulant is used, so the transferable result is the ranking, not the percentage.
What dust testing does not reproduce
Section titled “What dust testing does not reproduce”Ambient pressure. The VIPER dust box, the Martindale campaign and the seal torque sweeps were all run at ambient pressure [6]. Dust cohesion and adhesion change character below a few torr, and adhesion to a specific surface pair changes at pressures far lower than that, so an ambient exposure test bounds mechanical infiltration but not the adhesive behavior [1].
Quantified exposure. The VIPER team states directly that it is very difficult to quantitatively define the expected dust exposure to a mechanism, and that its approach was to overdesign and run conservative tests rather than to specify an exposure [6]. Ingress gaps across the mechanism designs, labyrinths included, were never assessed against a specific debris size and were left large for manufacturability.
Seal comparison. No published basis exists for choosing between labyrinth, felt, spring-energized PTFE and grease damming on measured performance, nor for the design variables within each, such as felt compression and width [6]. Labyrinth seal effectiveness against gap size in isolation is explicitly named as future work.
Charge transfer. Terrestrial atmosphere dissipates surface charge, so tribocharging measured in air does not transfer. The Martian case is measured in a 10 mbar CO2 atmosphere with dust driven onto a cylindrical insulator by an impeller fan, using JSC Mars-1 alongside its separate mineral constituents [9].
Abrasive fidelity. The standard abrasives named in the wear standards are harder and more aggressive than lunar simulant: alumina dominated the three-body result and is not representative, while the simulants matched silica sand only on soft specimens [3]. A result quoted against ASTM G65 or G76 media is therefore not a lunar wear rate.
No combined-environment standard. There is no standardized, accessible method for evaluating materials and mechanisms in a facsimile of the harsh lunar environment, so abrasive regolith, vacuum, temperature and radiation are usually applied to an article separately rather than together, and that gap is itself a brake on dust-tolerant technology [10].
References
- Gaier, J. R. and Sechkar, E. A. (2007). Lunar Simulation in the Lunar Dust Adhesion Bell Jar
. AIAA Aerospace Sciences Meeting and Exhibit, NASA/TM-2007-214704. Source
BibTeX
@inproceedings{gaier2007lunar, title = {Lunar Simulation in the Lunar Dust Adhesion Bell Jar}, author = {Gaier, James R. and Sechkar, Edward A.}, booktitle = {AIAA Aerospace Sciences Meeting and Exhibit}, number = {NASA/TM-2007-214704}, institution = {NASA}, year = {2007}, doi = {10.2514/6.2007-963}, abstract = {The Lunar Dust Adhesion Bell Jar has been assembled at the NASA Glenn Research Center to provide a high fidelity lunar simulation facility to test the interactions of lunar dust and lunar dust simulant with candidate aerospace materials and coatings. It has a sophisticated design which enables it to treat dust in a way that will remove adsorbed gases and create a chemically reactive surface. It can simulate the vacuum, thermal, and radiation environments of the Moon, including proximate areas of illuminated heat and extremely cold shadow. It is expected to be a valuable tool in the development of dust repellant and cleaning technologies for lunar surface systems.} } - Gerdts, S., Jimenez, N. and Dunlap, P. H. J. (2021). Lunar Simulant Deposition Technique for Dust Tolerance Studies
. NASA, 20210024128. Source
BibTeX
@techreport{gerdts2021lunar, title = {Lunar Simulant Deposition Technique for Dust Tolerance Studies}, author = {Gerdts, Stephen and Jimenez, Nathan and Dunlap, Patrick H., Jr.}, number = {20210024128}, institution = {NASA}, year = {2021}, url = {https://ntrs.nasa.gov/citations/20210024128}, abstract = {A renewed interest in lunar exploration has spawned an array of development efforts for lunar surface assets. These systems depend on the reliable operation of mechanisms and components that may be susceptible to performance degradations or failure due to dust. The Uniform Dust Deposition System was developed at the NASA Glenn Research Center to provide repeatable, uniform, and automated deposition of simulants on surfaces of interest for dust mitigation testing. The system is capable of depositing simulants on test articles up to 60 cm in diameter and 15 cm high in a dry air environment with less than 1 percent relative humidity while keeping users safe from aerosolized dust. The automation of the system allows for high testing throughput while not sacrificing test quality and allows the user to reduce data in parallel. The additional development of a simulant preparation technique complements the repeatability of the deposition physics during testing. The system includes an imaging subsystem that leverages the power of machine learning to count simulant particles and measure their size, thereby allowing for accurate predictions of surface deposition densities (coefficient of determination R^(2) = 0.93) from images alone. The coverage of dust on a surface was shown to be uniform (coefficient of variation CV < 0.11), allowing developers to accurately evaluate the performance of their technology with a prescribed amount of lunar simulant, information that can be used to develop and refine models. The accuracy of the system is currently less than desired for a single deposition run, with a standard deviation (SD) ranging from 18 to 24 mg, or 0.839 to 1.184 mg/sq. cm , for a 5-cm-diameter area. However, the accuracy can be improved by performing multiple deposition runs to build dust to a desired level. Testing has shown that a SD of 0.2 to 0.6 mg, or 0.076 to 0.227 mg/sq. cm, can be achieved for a 5-cm-diameter area using this technique. } } - Kobrick, R. L., Budinski, K. G., Street, K. W. J. and Klaus, D. M. (2010). Three-Body Abrasion Testing Using Lunar Dust Simulants to Evaluate Surface System Materials
. International Conference on Environmental Systems, NASA/TM-2010-216781. Source
BibTeX
@inproceedings{kobrick2010three, title = {Three-Body Abrasion Testing Using Lunar Dust Simulants to Evaluate Surface System Materials}, author = {Kobrick, Ryan L. and Budinski, Kenneth G. and Street, Kenneth W., Jr. and Klaus, David M.}, booktitle = {International Conference on Environmental Systems}, number = {NASA/TM-2010-216781}, institution = {NASA}, year = {2010}, doi = {10.2514/6.2010-6077}, abstract = {Numerous unexpected operational issues relating to the abrasive nature of lunar dust, such as scratched visors and spacesuit pressure seal leaks, were encountered during the Apollo missions. To avoid reoccurrence of these unexpected detrimental equipment problems on future missions to the Moon, a series of two- and three-body abrasion tests were developed and conducted in order to begin rigorously characterizing the effect of lunar dust abrasiveness on candidate surface system materials. Two-body scratch tests were initially performed to examine fundamental interactions of a single particle on a flat surface. These simple and robust tests were used to establish standardized measurement techniques for quantifying controlled volumetric wear. Subsequent efforts described in the paper involved three-body abrasion testing designed to be more representative of actual lunar interactions. For these tests, a new tribotester was developed to expose samples to a variety of industrial abrasives and lunar simulants. The work discussed in this paper describes the three-body hardware setup consisting of a rotating rubber wheel that applies a load on a specimen as a loose abrasive is fed into the system. The test methodology is based on ASTM International (ASTM) B611, except it does not mix water with the abrasive. All tests were run under identical conditions. Abraded material specimens included poly(methyl methacrylate) (PMMA), hardened 1045 steel, 6061-T6 aluminum (Al) and 1018 steel. Abrasives included lunar mare simulant JSC-1A-F (nominal size distribution), sieved JSC-1A-F (μm particle diameter), lunar highland simulant NU-LHT-2M, alumina (average diameter of 50 μm used per ASTM G76), and silica (50/70 mesh used per ASTM G65). The measured mass loss from each specimen was converted using standard densities to determine total wear volume in cm3. Abrasion was dominated by the alumina and the simulants were only similar to the silica (i.e., sand) on the softer materials of aluminum and PMMA. The nominal JSC-1A-F consistently showed more abrasion wear than the sieved version of the simulant. The lunar dust displayed abrasivity to all of the test materials, which are likely to be used in lunar landing equipment. Based on this test experience and pilot results obtained, recommendations are made for systematic abrasion testing of candidate materials intended for use in lunar exploration systems and in other environments with similar dust challenges.} } - Black, J. and Fritz, A. (2023). Investigating Abrasion Effects of Lunar Simulant Grain Sizes on Candidate Spacesuit Fabric
. IEEE Aerospace Conference, 20230000758. Source
BibTeX
@inproceedings{black2023investigating, title = {Investigating Abrasion Effects of Lunar Simulant Grain Sizes on Candidate Spacesuit Fabric}, author = {Black, Jacquelyne and Fritz, Amy}, booktitle = {IEEE Aerospace Conference}, number = {20230000758}, pages = {1-15}, institution = {NASA}, year = {2023}, doi = {10.1109/aero55745.2023.10115674}, abstract = {Lunar dust is identified as one of the most significant challenges during the Apollo exploration missions due to its extremely abrasive and electrostatic characteristics. As NASA and the space industry prepare for the upcoming Artemis missions, researching and testing with lunar simulant is quintessential to understanding the effects of lunar dust on the systems and equipment that will be deployed on the lunar surface. Testing will also provide paths that lead to developing technologies and cleaning tools that could be used for dust mitigation. Additionally, it is expected that any hardware that will be exposed to the dusty environment should undergo rigorous testing to ensure it will maintain long-term performance and operate on the lunar surface. For this study, exterior spacesuit fabric was observed. Abrasion is one of the main concerns of lunar dust exposure for spacesuit fabric. Three different abrasion methods were chosen: a rotary tumbler, the Martindale method, and Accelerotor. These abrasion methods were tested on coated and uncoated spacesuit material, Orthofabric, to understand the abrasion rates of sieved lunar simulant and investigate if the addition of ceramic coating mitigated dust abrasion. To summarize, the testing results provided that larger grains are more abrasive than smaller grains, and the selected ceramic coatings did not minimize abrasion during the controlled abrasion tests. It is important to note that the selected ceramic coatings were not designed or intended to provide protection from the abrasive lunar environment. It is recommended to select additional ceramic coatings with an elevated TRL of 5 or greater for testing with Orthofabric and lunar simulant. As an additional note, contact angle measurements were not accounted for in coating selection and should be a factor when selecting adhesion resistant coatings for lunar dust.} } - Stein, Z., Tirado-Pujols, A., Wohl, C., Wiesner, V. and Raghavan, S. (2024). Wear-Resistance Investigations on Ceramic Coatings for Lunar Dust Mitigation
. 75thInternational Astronautical Congress, 20240012146. Source
BibTeX
@inproceedings{stein2024wear, title = {Wear-Resistance Investigations on Ceramic Coatings for Lunar Dust Mitigation}, author = {Stein, Zachary and Tirado-Pujols, Ashley and Wohl, Christopher and Wiesner, Valerie and Raghavan, Seetha}, booktitle = {75thInternational Astronautical Congress}, number = {20240012146}, institution = {NASA}, address = {Milan}, year = {2024}, url = {https://ntrs.nasa.gov/citations/20240012146}, abstract = {Lunar dust has posed a major challenge to exploration efforts due to abrasion and impact. This work focuses on fundamental studies on ceramic coatings as candidates for enhanced resistance to impact and wear. As a first step, standard and modified approaches to the method of abrasion testing were explored for options to incorporate lunar regolith as wear media, the effects of which were presented for AL6061-T6 control samples. Following this, wear results for air plasma-sprayed (APS) alumina coatings were investigated due to their superior strength and surface hardness. In addition, APS 8 wt % yttria-stabilized zirconia (8YSZ) coatings were studied for their strength and martensitic transformation toughness. Measurements were made by assessing the mass loss, with a standard scale at various intervals. In addition, surface roughness was measured with a profilometer and features identified with a high-resolution microscope. The findings demonstrated that wear media has a distinct effect on the abrasion. The alumina coatings demonstrated improved wear over 8YSZ. However, the tailorability of 8YSZ makes it an attractive option to continue to modify as a wear-resistant coating to protect against lunar dust abrasion. The results of these measurements provide insight into the wear behavior of future directions in candidate ceramic coatings for the harsh lunar environment.} } - McBryan, E., Francis, P. and Sobey, A. (2025). Dust Mitigation for the VIPER Mobility System
. International Conference on Environmental Systems, 20250005201. Source
BibTeX
@inproceedings{mcbryan2025dust, title = {Dust Mitigation for the VIPER Mobility System}, author = {McBryan, Emily and Francis, Parker and Sobey, Alexander}, booktitle = {International Conference on Environmental Systems}, number = {20250005201}, institution = {NASA}, year = {2025}, doi = {10.32865/2346/108814}, abstract = {NASA’s Volatiles Investigating Polar Exploration Rover (VIPER) is built to prospect, provide ground truth measurements, and build regional maps of the volatiles at the lunar South Pole that were previously detected by Lunar Reconnaissance Orbiter (LRO), Lunar Crater Observation and Sensing Satellite (LCROSS), and Chandrayaan-1. The rover’s mobility system, responsible for navigating the moon’s partially defined terrain, is the part of VIPER that is most exposed to the lunar surface environment. To ensure it can survive the thermal extremes and lunar regolith, the VIPER project utilized resources across NASA centers to create and evaluate a multi-functional environmental protection strategy. The project’s approach combined thermal insulation with dust protection in a flexible barrier across dynamic actuated joints to serve as the first defense between the hardware and the environment. Additionally, the VIPER project integrated a selection of seals (labyrinth, Nomex felt, and spring-energized PTFE) with individual mechanisms to further mitigate dust infiltration and abrasion risk to the bearings, motors, and sensors. In stages, the project performed extensive testing through a matrix of simulated environmental parameters to evaluate performance margins from the component level to the integrated mobility system. This paper addresses the project’s lessons learned, with an emphasis on systems integration and how this work can affect future long-duration lunar surface systems, such as crewed unpressurized rovers and in-situ resource utilization robotics.} } - Gaier, J. R., Journey, K., Christopher, S. and Davis, S. (2011). Evaluation of Brushing as a Lunar Dust Mitigation Strategy for Thermal Control Surfaces
. International Conference on Environmental Systems, NASA/TM-2011-217231. Source
BibTeX
@inproceedings{gaier2011evaluation, title = {Evaluation of Brushing as a Lunar Dust Mitigation Strategy for Thermal Control Surfaces}, author = {Gaier, James R. and Journey, Khrissaundra and Christopher, Steven and Davis, Shanon}, booktitle = {International Conference on Environmental Systems}, number = {NASA/TM-2011-217231}, institution = {NASA}, address = {Portland, OR}, year = {2011}, url = {https://ntrs.nasa.gov/citations/20120000070}, abstract = {Evaluation of brushing to remove lunar simulant dust from thermal control surfaces is described. First, strip brushes made with nylon, PTFE, or Thunderon (Nihon Sanmo Dyeing Company Ltd.) bristles were used to remove JSC-1AF dust from AZ93 thermal control paint or aluminized FEP (AlFEP) thermal control surface under ambient laboratory conditions. Nylon and PTFE bristles removed a promising amount of dust from AZ93, and nylon and Thunderon bristles from AlFEP. But when these were tested under simulated lunar conditions in the lunar dust adhesion bell jar (LDAB), they were not effective. In a third effort, seven brushes made up of three different materials, two different geometries, and different bristle lengths and thicknesses were tested under laboratory conditions against AZ93 and AlFEP. Two of these brushes, the Zephyr fiberglass fingerprint brush and the Escoda nylon fan brush, removed over 90 percent of the dust, and so were tested in the fourth effort in the LDAB. They also performed well under these conditions recovering 80 percent or more of the original thermal performance (solar absorptance/thermal emittance) of both AZ93 and AgFEP after 20 strokes, and 90 or more percent after 200 strokes} } - Johansen, M. R., Dupuis, M. A., Phillips III, J. R., Malissa, J. D., Wang, J. J., Hogue, M. D. and Calle, C. I. (2019). Electrodynamic Dust Shield Testing on the Materials on International Space Station Experiment 11
. International Astronautical Congress, IAC-19-C2.6.2. Source
BibTeX
@inproceedings{johansen2019electrodynamic, title = {Electrodynamic Dust Shield Testing on the Materials on International Space Station Experiment 11}, author = {Johansen, Michael R. and Dupuis, Michael A. and Phillips III, James R. and Malissa, Joel D. and Wang, Jerry J. and Hogue, Michael D. and Calle, Carlos I.}, booktitle = {International Astronautical Congress}, number = {IAC-19-C2.6.2}, address = {Washington, Washington}, year = {2019}, url = {https://ntrs.nasa.gov/citations/20205006073}, abstract = {Dust is a major concern for lunar exploration. To combat the effects of dust, NASA, academia, and industry are developing solutions to the dust problem. One potential technology solution for this problem is the Electrodynamic Dust Shield (EDS). Many years of research and development have gone into this technology. The Materials on International Space Station Experiment – 11 (MISSE-11) provides a long term space exposure platform for this technology to verify compatibility of materials and manufacturing processes to the space environment. The MISSE-11 EDS experiment consists of 12 EDS panels. These panels are made of glass, polyimide, or prototype spacesuit fabric. Some panels are covered with a lotus leaf coating while others are covered with thermal paint. They are flown in the wake position of the ISS to simulate the lunar environment. Two panels are in an active configuration and are energized with a high voltage power supply, which generates high-voltage pulses to activate the dust shields. Current and voltage data are recovered from each of these trials to compare to baseline data. Also, each of the EDS panels are imaged on a monthly basis to track any changes with time that may occur with the EDS variants. In this paper, we report preliminary data and analysis from this spaceflight experiment.} } - Mantovani, J. G. (2001). A Study of the Electrostatic Interaction Between Insulators and Martian/Lunar Soil Simulants
. NASA Kennedy Space Center, 20020050541. Source
BibTeX
@techreport{mantovani2001study, title = {A Study of the Electrostatic Interaction Between Insulators and Martian/Lunar Soil Simulants}, author = {Mantovani, James G.}, number = {20020050541}, institution = {NASA Kennedy Space Center}, year = {2001}, url = {https://ntrs.nasa.gov/citations/20020050541}, abstract = {Using our previous experience with the Mars Environmental Compatibility Assessment (MECA) electrometer, we have designed a new type of aerodynamic electrometer. The goal of the research was to measure the buildup of electrostatic surface charge on a stationary cylindrical insulator after windborne granular particles have collided with the insulator surface in a simulated dust storm. The experiments are performed inside a vacuum chamber. This allows the atmospheric composition and pressure to be controlled in order to simulate the atmospheric conditions near the equator on the Martian surface. An impeller fan was used to propel the dust particles at a cylindrically shaped insulator under low vacuum conditions. We tested the new electrometer in a 10 mbar CO2 atmosphere by exposing two types of cylindrical insulators, Teflon (1.9 cm diameter) and Fiberglass (2.5 cm diameter), to a variety of windborne granular particulate materials. The granular materials tested were JSC Mars-1 simulant, which is a mixture of coarse and fine (<5microns diameter) particle sizes, and some of the major mineral constituents of the Martian soil. The minerals included Ottawa sand (SiO2), iron oxide (Fe2O3), aluminum oxide (Al2O3) and magnesium oxide (MgO). We also constructed a MECA-like electrometer that contained an insulator capped planar electrode for measuring the amount of electrostatic charge produced by rubbing an insulator surface over Martian and lunar soil simulants. The results of this study indicate that it is possible to detect triboelectric charging of insulator surfaces by windborne Martian soil simulant, and by individual mineral constituents of the soil simulant. We have also found that Teflon and Fiberglass insulator surfaces respond in different ways by developing opposite polarity surface charge, which decays at different rates after the particle impacts cease.} } - Wiesner, V. L., King, G. C., Domack, C. S., Widener, B. M., Gordon, K. L. and Wohl, C. J. (2024). Testbed for Lunar Extreme Environment Wear Tolerant Applications
. Aerospace Mechanisms Symposium. Source
BibTeX
@inproceedings{wiesner2024testbed, title = {Testbed for Lunar Extreme Environment Wear Tolerant Applications}, author = {Wiesner, Valerie L. and King, Glen C. and Domack, Christopher S. and Widener, Brandon M. and Gordon, Keith L. and Wohl, Christopher J.}, booktitle = {Aerospace Mechanisms Symposium}, address = {Hampton, Virginia}, year = {2024}, url = {https://ntrs.nasa.gov/citations/20240003704}, abstract = {The abrasive dust from lunar regolith poses significant long-term durability and performance challenges to materials, vehicles, mechanisms and structures that will be used for the next generation of lunar exploration. The development of advanced materials, coatings and device technologies that can withstand these abrasive particles and extreme environmental conditions is critical. However, the lack of standardized and accessible methods for evaluating such materials and devices in a facsimile of the harsh lunar environment hinders progress in dust-tolerant technologies. To address this challenge, NASA Langley Research Center is creating an extreme environment testbed. This reconfigurable testbed will allow rapid, repeatable wear testing of material and candidate mechanisms under vacuum conditions, facilitating the development of critical materials technologies for lunar exploration. Preliminary results from exposing an actuating mechanism similar to a pin joint to lunar regolith simulant under high vacuum are reported.} }