Dust Testing
The problem
Section titled “The problem”Lunar dust has to be kept out of mechanisms, off optics and radiators, and out of suit fabric, and the tests that decide whether it is have to reproduce a surface that cannot be reproduced on Earth. Apollo supplied the failure record: suit joints that lost pressure as dust clogged wrist bearings, boots and trousers worn through the outer layer, and radiators that lost thermal performance [22]. The surface itself is documented from six Apollo and three Luna sites, all within about 27 degrees of the equator [21], and the electrostatically levitated fine fraction and the regolith strength profile come from those same decades-old measurements [19].
Dust testing splits into five 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, whether an active removal system works, and how the dust itself is made representative. 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]. The Apollo mission record review that sorts the same problems found that ground tests consistently underestimated dust severity, most explicitly for brushing, which worked in the chamber and poorly on the Moon [27]. Inhalation is a separate health literature, reviewed from secondary sources only [20].
The tests below are ground tests with simulant. The exceptions are the Apollo brushing record [7], the MISSE-11 exposure of electrodynamic shield panels on the ISS [8], and the Apollo suit wear that the ground campaigns try to reproduce [4].
What has flown
Section titled “What has flown”Two items have left the ground. Brushing of Lunar Roving Vehicle radiators on Apollo 15, 16 and 17 was almost wholly ineffective [7]. Twelve electrodynamic dust shield panels flew on MISSE-11 on the ISS for one year, two energized and ten passive [8]. No dust-tolerant mechanism, seal or fabric tested below has a lunar surface wear result to compare with.
What is being tried now
Section titled “What is being tried now”Each family below is a ground test unless stated. Simulant fidelity and deposition control [1][2] and chambers [18] set the test environment; abrasion, seal and active removal campaigns follow. Electrostatic traveling-wave cleaning on ITO glass reached cleaning rates of 90 percent in 10 Pa vacuum with JSC-1A and FJS-1 at 800 V, 98 percent with ultrasonic assist, and removed Apollo 11 soil (0.04 g, one trial) qualitatively; the 1/6 g improvement is a simulation, not a test [31].
Dust and simulant fidelity
Section titled “Dust and simulant fidelity”A simulant from the bottle is not lunar dust. The 2005 MSFC workshop set the root and derivative framework still used: a low-titanium mare basalt and a high-calcium highland anorthosite as end members, with agglutinates, glass, nanophase iron and size fractions added to derivatives [22]. It was a recommendation document, and the report states that the claim of about 35 Apollo-era simulants could not be corroborated [22].
Bulk mechanics are a third gap: CSM highland simulants matching the lunar average particle size distribution within one standard deviation still differ in shear strength and compressibility, and CSM-LHT-T-30 shows triaxial cohesion of 17.3 kPa against 3.8 kPa for lunar highland regolith, with every value tied to a 90 percent relative density state [32].
Surface condition is the second gap. The Glenn bell jar facility specifies stirred pumpdown, a 200 C bake at 1e-6 torr until the residual gas spectrum is constant, three thermal cycles to about -150 C, an air plasma to remove organics, and a hydrogen-helium plasma to reduce surfaces and mimic solar wind implantation; the authors say only that they hope this creates the right surface defects [1]. The same paper concludes that clean cohesion appears below a few torr while adhesion work needs 1e-7 torr or better, and it does not simulate one-sixth gravity or energetic radiation [1].
The measured simulant gap for charging is one number. Single Apollo 17 and Luna 24 grains levitated in an electrodynamic balance showed photoelectric yield falling by about an order of magnitude below roughly 1 micrometer radius, and the yields disagreed with the one earlier bulk fines measurement by factors of about 15 to 38 [12]. For wear testing, a simulant selection study ranked candidates (Exolith LHS-1, LMS-1, MGS-1, JEZ-1, TUBS-M, TUBS-T, GreenSpar, OB-1) against explicit criteria and found particle size distribution and composition documented adequately for only a subset. It measured nothing and chose by mineralogy and shape as proxies for abrasivity [11].
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].
Environmental chambers
Section titled “Environmental chambers”Chambers that hold loose simulant under vacuum face a containment problem before any test starts. The MSFC Lunar Environments Test System combined a cryopumped vessel about 2.5 ft in diameter with 75 kg of JSC-1A at 1e-7 torr, quartz lamp heating to +150 C, VUV lamps and an electron flood gun [18]. Its one reported measurement was a fall-out plate count showing that dust escapes the simulant box during pumpdown, mostly in the smallest size bins. The liquid nitrogen shroud and proton source were listed as not yet installed, so those capabilities are not demonstrated [18]. The Glenn bell jar places the diffusion pump behind five baffles and an offset antechamber for the same reason, and reaches about 1e-7 torr against a lunar surface value of 1e-10 to 1e-14 torr [1].
Vacuum changes the tribology independently of dust. The 1962 NASA bell-jar program found that steel-on-steel friction is not monotonic in pressure: 52100 on 52100 falls from 0.45 at 760 mm Hg to about 0.2 between 1e-1 and 1e-2 mm Hg, and at 1e-6 mm Hg enough oxygen remained to re-form iron oxides on transferred metal, so low friction coefficients measured there overstate what a lunar surface pair would show [15]. That is the reason an ambient abrasion number does not transfer.
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].
Fabric testing at JSC ran Orthofabric, the outer layer of the xEMU reference suit, through a rotary drum tumbler, the Martindale method and an Accelerotor. Its finding that larger grains abrade more rests on visual comparison of microscope images; the authors’ own tumbler tensile data (one sample per condition) does not correlate with it, and only the tumbler used simulant [4]. The result that is supported is negative: two consumer ceramic coatings lowered puncture strength after Accelerotor abrasion (155.75 and 192.2 lbf against 219.4 lbf uncoated) [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].
Abrasion is not the only wear mode. Plume-driven dust impacting at speed erodes surfaces, which is how Surveyor 3 was affected by the Apollo 12 landing. Shots of 250 to 350 micrometer JSC-1A at up to about 360 m/s raised aluminum roughness by a factor of 8 or more after a single impact, while silica glass lost about 25 percent of transmittance; the study used one size band, normal incidence and small samples [14]. The Mars 2020 qualification exposed a white thermal control paint, Kapton flex cable, fiber optic cable, HEPA filter and graphite composite to entrained regolith of 38 to 550 micrometers at 80 to 250 m/s, plus larger gravel on a gravelometer and gas gun, and every material survived the expected landing environment. The rigs ran at ambient pressure with basaltic particles, and the requirement rests on extrapolated Apollo-era plume models because current CFD cannot resolve a real landing [13].
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].
The IPEx actuator qualification ran a dirty vacuum test in which a dust cup continuously conveyed regolith over the rotating output and submerged the lower actuator. Significant dust penetrated the labyrinth stage, minimal dust passed the felt seal, and the actuator completed the full operations sequence, so one felt seal was sufficient there [24]. All of that testing was at 1 g [24]. The later Gen 1 actuator campaign measured a maximum seal drag torque of 0.03, under 1 percent of the overall load, in vacuum; dust exclusion itself was not tested in that campaign [29].
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.
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.
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 earlier laboratory demonstration used transparent electrodes on 5 by 5 cm commercial solar cells, and output recovered from 11 to 23 percent of baseline after dust loading to above 90 percent within about two minutes of activation with JSC-1A [16]. The test ran at 1 kPa, not high vacuum, with four electrode spacings and no lunar gravity [16]. A mitigation survey scored candidates in four layers (avoid generating dust, prevent sticking or entry, remove, tolerate) and recommended lotus leaf coatings, spring-loaded Teflon shaft seals, beta cloth for boots and bellows, the shield, and ceramic bearings. The scoring is subjective and reports no removal efficiency, adhesion force or abrasion rate [17].
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 [7].
What is not established
Section titled “What is not established”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. 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]. The one chamber built to combine them at laboratory scale had not installed its cold shroud or proton source at the time it was reported [18].
Polar regolith. The regolith property data behind simulant specification are equatorial and mid-latitude, and the sources do not qualify them for polar or permanently shadowed soil, which has been argued to be looser [23]. Dust testing for polar missions therefore starts from a surface whose mechanical state is itself inferred.
Flight validation. None of the ground abrasion, seal or coating results above is correlated against lunar surface wear data, so a ground ranking is the strongest claim any of them supports [4][5].
Gravity. The Glenn bell jar does not simulate one-sixth gravity [1], and the IPEx dirty vacuum test ran at 1 g [24]. Parabolic flight campaigns with soil and wheel both at lunar gravity show what a 1 g test omits for granular contact: reduced-weight testing at matched wheel load overstated mobility, with drawbar pull to weight down 20 percent or more and sinkage up to 40 percent in lunar gravity. Granular scaling laws came within 8.5 percent on drawbar pull and erred conservatively [25]. Cable-suspension offload of suited subjects at ARGOS has its own limits: only the body segments inboard of the attachment are offloaded, and the pivot cannot follow a center of gravity that moves with posture [28]. That work concerns wheel-soil traction, not dust ingress, and no equivalent comparison is published for dust deposition, adhesion or seal infiltration. The NASA mobility test best-practices review states that no NASA standard simulant exists for the south pole, that all simulant choices extrapolate from Apollo equatorial data, and that cone index gradient matching under a different gravity field is of uncertain validity [30].
Excavator dust exposure. The RASSOR 2.0 excavator that IPEx descends from was built and tested on BP-1 terrain without vacuum, thermal or dust testing, which the paper defers to a later vehicle [26]. Its dust tolerance rests on the later IPEx actuator test [24], not on this design record.
References
- Gaier, J. R. and Sechkar, E. A. (2007). Lunar Simulation in the Lunar Dust Adhesion Bell Jar
. AIAA Aerospace Sciences Meeting, 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}, 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.} } - Barkó, G., Kalácska, G., Keresztes, R., Zsidai, L., Shegawu, H. and Kalácska, Á. (2023). Abrasion Evaluation of Moon and Mars Simulants on Rotating Shaft/Sealing Materials: Simulants and Structural Materials Review and Selection
. Lubricants, 8. Source
BibTeX
@article{barko2023abrasion, title = {Abrasion Evaluation of Moon and Mars Simulants on Rotating Shaft/Sealing Materials: Simulants and Structural Materials Review and Selection}, author = {Barkó, György and Kalácska, Gábor and Keresztes, Róbert and Zsidai, László and Shegawu, Hailemariam and Kalácska, Ádám}, journal = {Lubricants}, volume = {11}, number = {8}, pages = {334}, publisher = {MDPI AG}, year = {2023}, doi = {10.3390/lubricants11080334}, abstract = {Tribological testing of moving shaft/sealing pairs in complex environments is at the frontline of research. Machines working in abrasive conditions are subject to different wear effects. It is not only valid on Earth but especially valid for rovers and future robots used in Mars and Moon missions. The aim of our joint research with the European Space Agency is to study the abrasion phenomena of moving machine elements on Mars and the Moon by using artificial soil samples (“simulants”). This review details mainly the available simulant sources and recommend a selection of the most suitable ones for tribological testing. Moreover, the potential mating structural materials subjected to abrasive space applications are reviewed briefly. The tribological tests are exploring the features of the rotary shaft/seal relationship that is subject to dry friction and intense abrasion. By using the simulants, measurements are performed under laboratory conditions with both a sample test and a real shaft/seal connection. Parameters of the selection criteria were defined, and classification of the simulant sources were made. It was found that simulant particle size distribution and chemical substance content are detailed enough only for a limited type of available artificial Moon and Mars soil samples. Four simulants were identified and applied later in the tribological testing. For the shaft materials, based on a detailed case study of polymers, steel, and aluminum alloys, a high-strength aluminum alloy with a hard anodized surface and a stainless steel were selected for further abrasion tests.} } - Abbas, M. M., Tankosic, D., Craven, P. D., Spann, J. F., LeClair, A. and West, E. A. (2007). Lunar Dust Charging by Photoelectric Emissions
. Planetary and Space Science, 20070014798. Source
BibTeX
@article{abbas2007lunar, title = {Lunar Dust Charging by Photoelectric Emissions}, author = {Abbas, M. M. and Tankosic, D. and Craven, Paul D. and Spann, J. F. and LeClair, A. and West, E. A.}, journal = {Planetary and Space Science}, volume = {55}, number = {20070014798}, pages = {953-965}, institution = {NASA}, year = {2007}, doi = {10.1016/j.pss.2006.12.007}, abstract = {The lunar surface is covered with a thick layer of sub-micron/micron size dust grains formed by meteoritic impact over billions of years. The fine dust grains are levitated and transported on the lunar surface, as indicated by the transient dust clouds observed over the lunar horizon during the Apollo 17 mission. Theoretical models suggest that the dust grains on the lunar surface are charged by the solar UV radiation as well as the solar wind. Even without any physical activity, the dust grains are levitated by electrostatic fields and transported away from the surface in the near vacuum environment of the Moon. The current dust charging and levitation models, however, do not fully explain the observed phenomena. Since the abundance of dust on the Moon s surface with its observed adhesive characteristics has the potential of severe impact on human habitat and operations and lifetime of a variety of equipment, it is necessary to investigate the charging properties and the lunar dust phenomena in order to develop appropriate mitigating strategies. Photoelectric emission induced by the solar UV radiation with photon energies higher than the work function of the grain materials is recognized to be the dominant process for charging of the lunar dust, and requires measurements of the photoelectric yields to determine the charging and equilibrium potentials of individual dust grains. In this paper, we present the first laboratory measurements of the photoelectric efficiencies and yields of individual sub-micron/micron size dust grains selected from sample returns of Apollo 17, and Luna 24 missions, as well as similar size dust grains from the JSC-1 simulants. The measurements were made on a laboratory facility based on an electrodynamic balance that permits a variety of experiments to be conducted on individual sub-micron/micron size dust grains in simulated space environments. The photoelectric emission measurements indicate grain size dependence with the yield increasing by an order of magnitude for grains of sub-micron to several micron size radii, at which it reaches asymptotic values. The yield for large size grains is found to be more than an order of magnitude higher than the bulk measurements on lunar fines reported in the literature.} } - Bradford, E., Rabinovitch, J. and Abid, M. (2019). Regolith Particle Erosion of Material in Aerospace Environments
. IEEE Aerospace Conference. Source
BibTeX
@inproceedings{bradford2019regolith, title = {Regolith Particle Erosion of Material in Aerospace Environments}, author = {Bradford, Emma and Rabinovitch, Jason and Abid, Mohamed}, booktitle = {IEEE Aerospace Conference}, pages = {1-15}, publisher = {IEEE}, year = {2019}, doi = {10.1109/aero.2019.8741563} } - Bühler, C. A. (2015). Experimental investigation of lunar dust impact wear
. Wear. Source
BibTeX
@article{buhler2015experimental, title = {Experimental investigation of lunar dust impact wear}, author = {Bühler, Christian Alexander}, journal = {Wear}, volume = {342-343}, pages = {244-251}, publisher = {Elsevier BV}, year = {2015}, doi = {10.1016/j.wear.2015.09.002} } - Buckley, D. H., Swikert, M. and Johnson, R. L. (1962). Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 1e-7 mm Hg
. ASLE Transactions. Source
BibTeX
@article{buckley1962friction, title = {Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 1e-7 mm Hg}, author = {Buckley, Donald H. and Swikert, Max and Johnson, Robert L.}, journal = {ASLE Transactions}, volume = {5}, pages = {8--23}, year = {1962}, url = {https://ntrs.nasa.gov/citations/20150020881}, abstract = {The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.} } - Calle, C. I., Buhler, C. R., McFall, J. L. and Snyder, S. (2009). Particle removal by electrostatic and dielectrophoretic forces for dust control during lunar exploration missions
. Journal of Electrostatics. Source
BibTeX
@article{calle2009particle, title = {Particle removal by electrostatic and dielectrophoretic forces for dust control during lunar exploration missions}, author = {Calle, Carlos I. and Buhler, C. R. and McFall, J. L. and Snyder, Sarah}, journal = {Journal of Electrostatics}, volume = {67}, pages = {89-92}, year = {2009}, doi = {10.1016/j.elstat.2009.02.012}, abstract = {Particle removal during lunar exploration activities is of prime importance for the success of robotic and human exploration of the moon. We report on our efforts to use electrostatic and dielectrophoretic forces to develop a dust removal technology that prevents the accumulation of dust on solar panels and removes dust adhering to those surfaces. Testing of several prototypes showed solar shield output above 90% of the initial potentials after dust clearing.} } - Cannon, K. M., Dreyer, C. B., Sowers, G. F., Schmit, J., Nguyen, T., Sanny, K. and Schertz, J. (2022). Working with lunar surface materials: Review and analysis of dust mitigation and regolith conveyance technologies
. Acta Astronautica. Source
BibTeX
@article{cannon2022working, title = {Working with lunar surface materials: Review and analysis of dust mitigation and regolith conveyance technologies}, author = {Cannon, Kevin M. and Dreyer, Christopher B. and Sowers, George F. and Schmit, John and Nguyen, Thao and Sanny, Keoni and Schertz, Joshua}, journal = {Acta Astronautica}, volume = {196}, pages = {259--274}, year = {2022}, doi = {10.1016/j.actaastro.2022.04.037}, abstract = {The Moon's dusty surface environment threatens any equipment that operates there, especially for long-duration infrastructure needed for a sustained lunar presence. This is doubly true for systems that convey regolith, which by agitating the soil are certain to generate dust. Here, we provide a comprehensive review of technologies that have been proposed to convey regolith on the lunar surface, and to mitigate against dust hazards that are generated by such transport systems. We define functional taxonomies for both regolith conveyance and dust mitigation, then carry out quantitative trade studies in several categories for each. Examples include passive and active dust mitigation, and horizontal and near vertical conveyance. Conveyance technologies that scored particularly high include wheeled haulers, conveyor belts, and auger/hopper transfer points. High scoring dust mitigation technologies include the lotus leaf passive coating, Electrodynamic Dust Shield, and boots or bellow made of fiberglass fabric. We also explore novel or unconventional concepts and describe how dust mitigation and regolith conveyance can be combined using a systems approach with multiple technologies layered together. The results from the trade studies and the subsequent recommendations constitute a practical guide that can be used for designing and developing systems that must perform efficiently and reliably to carry out useful tasks on the Moon or Mars, such as resource extraction, construction, and additive manufacturing.} } - Craven, P., Vaughn, J., Schneider, T., Norwood, J., Abbas, M. and Alexander, R. (2009). MSFC Lunar Environments Test System (LETS) System Development, 20090025947. ntrs.nasa.gov/citations/20090025947
BibTeX
@misc{craven2009msfc, title = {MSFC Lunar Environments Test System (LETS) System Development}, author = {Craven, Paul and Vaughn, Jason and Schneider, Todd and Norwood, Joey and Abbas, Mian and Alexander, Reginald}, howpublished = {Presentation at the NASA Marshall Space Flight Center}, number = {20090025947}, year = {2009}, url = {https://ntrs.nasa.gov/citations/20090025947}, abstract = {A review of the NASA MSFC Lunar Environment Test System (LETS) System Development is presented. The contents include: 1) MSFC LETS Chamber Status; 2) LETS Simulant Containment Box Development; 3) Tests Conducted in LETS To date: Simulant Dust Migration; 4) Summary; and 5) Forward Work.} } - Colwell, J. E., Batiste, S., Horányi, M., Robertson, S. and Sture, S. (2007). Lunar surface: Dust dynamics and regolith mechanics
. Reviews of Geophysics. Source
BibTeX
@article{colwell2007lunar, title = {Lunar surface: Dust dynamics and regolith mechanics}, author = {Colwell, J. E. and Batiste, S. and Horányi, Mihály and Robertson, Scott and Sture, Stein}, journal = {Reviews of Geophysics}, volume = {45}, pages = {RG2006}, publisher = {American Geophysical Union (AGU)}, year = {2007}, doi = {10.1029/2005rg000184}, abstract = {The lunar surface is characterized by a collisionally evolved regolith resulting from meteoroid bombardment. This lunar soil consists of highly angular particles in a broad, approximately power law size distribution, with impact‐generated glasses. The regolith becomes densified and difficult to excavate when subjected to lunar quakes or, eventually, manned and unmanned activity on the surface. Solar radiation and the solar wind produce a plasma sheath near the lunar surface. Lunar grains acquire charge in this environment and can exhibit unusual behavior, including levitation and transport across the surface because of electric fields in the plasma sheath. The fine component of the lunar regolith contributes to the operational and health hazards posed to planned lunar expeditions. In this paper we discuss the mechanical response of the regolith to anticipated exploration activities and review the plasma environment near the lunar surface and the observations, models, and dynamics of charged lunar dust.} } - Cain, J. R. (2010). Lunar dust: The Hazard and Astronaut Exposure Risks
. Earth, Moon, and Planets, 1. Source
BibTeX
@article{cain2010lunar, title = {Lunar dust: The Hazard and Astronaut Exposure Risks}, author = {Cain, John R.}, journal = {Earth, Moon, and Planets}, volume = {107}, number = {1}, pages = {107--125}, publisher = {Springer Science and Business Media LLC}, year = {2010}, doi = {10.1007/s11038-010-9365-0} } - Heiken, G. H., Vaniman, D. T. and French, B. M. (1991). Lunar Sourcebook: A User's Guide to the Moon
. Endeavour. Source
BibTeX
@book{heiken1991lunar, title = {Lunar Sourcebook: A User's Guide to the Moon}, author = {Heiken, Grant H. and Vaniman, David T. and French, Bevan M.}, journal = {Endeavour}, volume = {16}, pages = {96}, publisher = {Cambridge University Press}, year = {1991}, doi = {10.1016/0160-9327(92)90014-g} } - Sibille, L., Carpenter, P., Schlagheck, R. and French, R. A. (2006). Lunar Regolith Simulant Materials: Recommendations for Standardization, Production, and Usage
. NASA Marshall Space Flight Center, NASA/TP-2006-214605. Source
BibTeX
@techreport{sibille2006development, title = {Lunar Regolith Simulant Materials: Recommendations for Standardization, Production, and Usage}, author = {Sibille, Laurent and Carpenter, Paul and Schlagheck, R. and French, R. A.}, number = {NASA/TP-2006-214605}, institution = {NASA Marshall Space Flight Center}, type = {NASA Technical Publication}, year = {2006}, url = {https://ntrs.nasa.gov/citations/20060051776}, abstract = {Experience gained during the Apollo program demonstrated the need for extensive testing of surface systems in relevant environments, including regolith materials similar to those encountered on the lunar surface. As NASA embarks on a return to the Moon, it is clear that the current lunar sample inventory is not only insufficient to support lunar surface technology and system development, but its scientific value is too great to be consumed by destructive studies. Every effort must be made to utilize standard simulant materials, which will allow developers to reduce the cost, development, and operational risks to surface systems. The Lunar Regolith Simulant Materials Workshop held in Huntsville, AL, on January 24 26, 2005, identified the need for widely accepted standard reference lunar simulant materials to perform research and development of technologies required for lunar operations. The workshop also established a need for a common, traceable, and repeatable process regarding the standardization, characterization, and distribution of lunar simulants. This document presents recommendations for the standardization, production and usage of lunar regolith simulant materials.} } - Connolly, J. F. and Carrier, W. D. (2023). An Engineering Guide to Lunar Geotechnical Properties
. IEEE Aerospace Conference. Source
BibTeX
@inproceedings{connolly2023engineering, title = {An Engineering Guide to Lunar Geotechnical Properties}, author = {Connolly, John F. and Carrier, W. David}, booktitle = {IEEE Aerospace Conference}, pages = {1-9}, address = {Big Sky, Montana}, year = {2023}, doi = {10.1109/aero55745.2023.10115961}, abstract = {The renewed interest in returning human and robotic explorers to the lunar surface has identified a need for a renewed understanding of lunar geotechnical properties related to landing, exploration, excavation, and construction activities on the lunar surface. This paper summarizes measurements conducted during US and Russian/Soviet landed missions as well as experiments performed on returned samples to establish fundamental geotechnical properties such as particle size distribution, particle shape, bulk density, shear strength, cohesion and bearing strength. While many of these properties are well known, how they vary with increased lunar soil depth is less understood, and those properties that vary significantly as a function of depth are explored in additional detail. Selected examples discuss mechanical excavation forces, rocket exhaust erosion forces, and the preparation of launch/landing pad surfaces, with the goal of a better understanding of lunar soil geotechnical properties that apply to large-scale exploration of the lunar surface and dictate the design of future exploration systems.} } - Schuler, J. M., Smith, J. D., Nick, A. J., Buckles, B. C., Dyas, J. E., Ortega, V. V., Cloud, J. M., Dokos, A. G., Zhang, E. L., Wang, J. J., Baron, M. A., Muller, T. J., Clark, C. J. and Howe, M. W. (2024). ISRU Pilot Excavator (IPEx) Technology Readiness Level 5 Design Overview
. AIAA AVIATION Forum and ASCEND, 20240008162. Source
BibTeX
@inproceedings{schuler2024isru, title = {ISRU Pilot Excavator (IPEx) Technology Readiness Level 5 Design Overview}, author = {Schuler, Jason M. and Smith, Jonathan D. and Nick, Andrew J. and Buckles, Bradley C. and Dyas, Jeffrey E. and Ortega, Victoria V. and Cloud, Joseph M. and Dokos, Adam G. and Zhang, Elizabeth L. and Wang, Jerry J. and Baron, Michael A. and Muller, Thomas J. and Clark, Casey J. and Howe, Musashi W.}, booktitle = {AIAA AVIATION Forum and ASCEND}, number = {20240008162}, institution = {NASA}, year = {2024}, doi = {10.2514/6.2024-4890}, abstract = {This paper details the mechanical and mechatronic design of the Technology Readiness Level (TRL)-5 In-Situ Resource Utilization (ISRU) Pilot Excavator (IPEx). IPEx is a robotic excavator designed for a technology demonstration of regolith mining in the lunar south pole region. The novel design uses pairs of counter-acting excavation tools called bucket drums, that dig at the same time in opposing directions to reduce the reaction force needed, thereby enabling mining with a small, low-mass, robotic system. IPEx builds on the prior work of the Regolith Advanced Surface Systems Operations Robot (RASSOR), which is the TRL-4 implementation of this concept. The TRL-5 IPEx subsystems that are discussed in this paper include: Regolith Delivery Subsystem (RDS), Mobility Subsystem (MS), Cameras and Dust Mitigation Subsystem (CDMS), and Thermal Control Subsystem (TCS). Each subsystem is described in detail with rationale for design selections. Dust tolerance is a key feature for IPEx, and this paper details a thermal control system with an actuated radiator cover and phase change material as well as camera modules with removable electrodynamic dust shields (EDS). Additional components such as actuators, wheels, and bucket drums are discussed in detail. Due to their complexity, the avionics and software subsystems will be discussed in a separate publication.} } - Daca, A. (2023). Predicting Planetary Rover Mobility in Reduced Gravity Using 1-g Experiments
. Unpublished. Source
BibTeX
@phdthesis{daca2023predicting, title = {Predicting Planetary Rover Mobility in Reduced Gravity Using 1-g Experiments}, author = {Daca, Adriana}, journal = {Unpublished}, school = {Concordia University}, address = {Montreal, Quebec, Canada}, type = {PhD thesis}, month = {February}, year = {2023}, doi = {10.13140/rg.2.2.12718.28485}, abstract = {Traversing granular regolith, especially in reduced gravity environments, remains a potential challenge for wheeled rovers. Mitigating hazards for planetary rovers requires testing in representative environments, but direct Earth-based testing fails to account for the effect of reduced gravity on the soil itself. Here, experimental apparatus and techniques for reduced-gravity flight testing are used to systematically evaluate three existing Earth-based testing methods and develop guidelines for their use and interpretation: (i) reduced-weight testing, (ii) matching soil testing instrument response through soil simulant design, and (iii) granular scaling laws (GSL). \nExperimentation campaigns flying reduced-gravity parabolas, with soil and wheel both in lunar-g, have shown reductions in net traction of 20% or more and increases in sinkage of up to 40% compared to Earth-based testing methods (i) and (ii). Scaled-wheel testing, according to GSL (method iii) has shown better agreement with reduced-g tests (less than 10% error) and also tends to err on the side of conservative predictions. \nLimitations of GSL are investigated including a recently proposed cohesion constraint (that the wheel radius ratio must be the inverse of the gravity ratio) and the effects of wheel size and aspect ratio on GSL’s accuracy. It was found that the cohesion constraint can most likely be ignored for mildly cohesive soils such as lunar regolith. Limits on wheel sizes and aspect ratio variation are also proposed. \nThe application of GSL to planetary rover testing is demonstrated through two studies undertaken in collaboration with NASA’s Jet Propulsion Laboratory. One study compares wheel designs for a skid-steer lunar rover in single-wheel tests scaled by GSL, demonstrating that diagonal grousers improve turning performance without requiring larger wheels. The second study involves application of GSL to the design of two reconfigurable test platforms for evaluating steep-terrain mobility performance. \nAnother aspect of rover mobility testing—normal force control in single-wheel testbeds—is also investigated. An improved method for single-wheel testing, using a 4-bar mechanism, essentially eliminates normal force oscillations from frictional vertical sliders. \nFinally, guidelines for conducting and interpreting 1-g mobility tests for lunar rovers are presented, and potential avenues for future research are outlined.} } - Mueller, R. P., Smith, J. D., Schuler, J. M., Nick, A. J., Gelino, N. J., Leucht, K. W., Townsend, I. I. and Dokos, A. G. (2016). Design of an Excavation Robot: Regolith Advanced Surface Systems Operations Robot (RASSOR) 2.0
. ASCE Earth and Space Conference, 20210011366. Source
BibTeX
@inproceedings{mueller2016design, title = {Design of an Excavation Robot: Regolith Advanced Surface Systems Operations Robot (RASSOR) 2.0}, author = {Mueller, Robert P. and Smith, Jonathan D. and Schuler, Jason M. and Nick, Andrew J. and Gelino, Nathan J. and Leucht, Kurt W. and Townsend, Ivan I. and Dokos, Adam G.}, booktitle = {ASCE Earth and Space Conference}, number = {20210011366}, pages = {163-174}, institution = {NASA}, year = {2016}, doi = {10.1061/9780784479971.018}, abstract = {To continue on a sustainable and flexible path, NASA needs to address the challenge of collecting and moving large amounts of regolith at the destination. Acquiring the water resources on Mars will require mining significant quantities of regolith, and this is not possible with the state-of-the-art low mass excavation systems. Low gravity environments (Mars = 3/8G) and launch mass restrictions limit the traction and the resulting reaction force of the vehicle, making current terrestrial techniques impractical. This project addressed this challenge by developing a completely new technology that can mine large quantities of regolith on Mars. Recent measurements by the “Curiosity” rover on Mars have found that the regolith contains ~2% water by weight globally, ~4% in Jezero Crater (Human Architecture Team’s reference landing site), and much more at the poles. RASSOR 2.0 is a planetary excavator, which has a mass of 66 kg, with a 0.38 kg vehicle mass per kilogram, per hour of excavation rate and power usage of 4 W per kg of regolith excavation rate. A single RASSOR 2.0 can excavate a minimum of 2.7 metric tons of regolith per day. This is accomplished by using counteracting excavation forces on two opposing digging implements called bucket drums and an autonomous mining control system. This work has addressed several major research areas outlined in the NASA Technology Area (TA) 04 Robotics and Autonomous Systems and TA 07 Human Destination Systems roadmaps. This project started at Technology Readiness Level (TRL) 4 as a low fidelity “proof of concept” prototype which has successfully demonstrated basic regolith simulant excavation functionality in a lab-scale gravity off load test. The foundational technology described here was awarded US patent number: US 9027265 for a “Zero horizontal reaction force excavator” on May 12, 2015.} } - Gaier, J. R. (2007). The Effects of Lunar Dust on EVA Systems During the Apollo Missions
. NASA, NASA/TM-2005-213610/REV1. Source
BibTeX
@techreport{gaier2007effects, title = {The Effects of Lunar Dust on EVA Systems During the Apollo Missions}, author = {Gaier, James R.}, number = {NASA/TM-2005-213610/REV1}, institution = {NASA}, year = {2007}, url = {https://ntrs.nasa.gov/citations/20070021819}, abstract = {Mission documents from the six Apollo missions that landed on the lunar surface have been studied in order to catalog the effects of lunar dust on Extra-Vehicular Activity (EVA) systems, primarily the Apollo surface space suit. It was found that the effects could be sorted into nine categories: vision obscuration, false instrument readings, dust coating and contamination, loss of traction, clogging of mechanisms, abrasion, thermal control problems, seal failures, and inhalation and irritation. Although simple dust mitigation measures were sufficient to mitigate some of the problems (i.e., loss of traction) it was found that these measures were ineffective to mitigate many of the more serious problems (i.e., clogging, abrasion, diminished heat rejection). The severity of the dust problems were consistently underestimated by ground tests, indicating a need to develop better simulation facilities and procedures.} } - Jarvis, S. L., Vu, L. Q., Gupta, G., Benson, E., Kim, K. H., Rhodes, R. and Rajulu, S. L. (2023). Development of ARGOS (Active Response Gravity Offload System) Offloading Assessments and Methodology for Lunar EVA Simulations
. International Conference on Environmental Systems, 20230002430. Source
BibTeX
@inproceedings{jarvis2023development, title = {Development of ARGOS (Active Response Gravity Offload System) Offloading Assessments and Methodology for Lunar EVA Simulations}, author = {Jarvis, Sarah L. and Vu, Linh Q. and Gupta, Garima and Benson, Elizabeth and Kim, K. Han and Rhodes, Richard and Rajulu, Sudhakar L.}, booktitle = {International Conference on Environmental Systems}, number = {20230002430}, institution = {NASA}, address = {Calgary}, year = {2023}, url = {https://ntrs.nasa.gov/citations/20230002430}, abstract = {The Active Response Gravity Offload System (ARGOS) at NASA Johnson Space Center (JSC) is an analog environment that can offload pressurized suited subjects for various reduced gravity simulations. The suit is suspended from a robotic overhead crane by a cable connected to the suit via a gimbal with an adjustable pivot point (i.e. offload attachment). There has been increased interest in providing planetary pressurized suited training at ARGOS in preparation for lunar missions. Determination of the appropriate gimbal pivot point location for a given subject is vital for a high-fidelity functional lunar simulation. Interactions between the pivot point location and human-spacesuit center of gravity (CG) can result in righting moments that may lead to artificially stable or unrealistically challenging configurations. Changing the pivot point location is time consuming and repeated adjustment can result in loss of valuable pressurized suited time. This paper aims to share knowledge obtained from the offloading characterization efforts during pressurized suited testing at ARGOS and document the ongoing process to define an appropriate pivot point location through iterative quantitative and qualitative assessments. Human-spacesuit CG locations for the ARGOS lunar simulation were estimated using a 3D body scan and density model combined with spacesuit hardware CAD and specifications. Early pilot testing of the gimbal revealed that setting the pivot point coincident with the modeled CG location was not always possible due to the current gimbal design, and small pivot point shifts had noticeable effects on subject stability. Fourteen subjects performed a series of CG-related tasks in the Exploration Extravehicular Mobility Unit (xEMU) to assess simulation characteristics. Through iterative testing, this task list evolved to streamline the process needed to efficiently identify a suitable pivot point for a given subject. The developed methodology will be critical for pivot point selection during astronaut training in the ARGOS environment.} } - Clark, C. J., Smith, J. D., Nick, A. J., Ortega, V. V., Schuler, J. M., Dyas, J. E. and Lahl, J. (2025). Design and Testing of TRL5 IPEx Actuators
. IEEE Aerospace Conference, 20250000003. Source
BibTeX
@inproceedings{clark2025design, title = {Design and Testing of TRL5 IPEx Actuators}, author = {Clark, Casey J. and Smith, Jonathan Drew and Nick, Andrew J. and Ortega, Victoria V. and Schuler, Jason M. and Dyas, Jeffrey E. and Lahl, John}, booktitle = {IEEE Aerospace Conference}, number = {20250000003}, institution = {NASA}, address = {Big Sky, MT}, year = {2025}, url = {https://ntrs.nasa.gov/citations/20250000003}, abstract = {NASA is advancing In-Situ Resource Utilization (ISRU) by focusing on missions aimed at establishing sustainable infrastructure on the Moon and Mars. On the Moon, regolith serves as the most abundant resource. To support ISRU objectives, a 30-kg-class robot called ISRU Pilot Excavator (IPEx) is being developed to excavate 10,000 kg of lunar regolith during a future technology demonstration mission. IPEx uses novel excavation tools, called bucket drums, which are hollow cylinders with scoops staggered around the outside. Regolith is collected with the scoops and flows into the drum where it is captured by an internal baffle system. The excavator can then transport the regolith in the drum and reverse the direction of the drum rotation to dispense the regolith out. IPEx uses two sets of bucket drums that dig simultaneously in opposing directions and results in counteracting excavation forces. This combination of bucket drum excavation tools and counteracting excavation forces enables low mass robotic excavators to effectively dig in reduced gravity environments. This is a significant departure from terrestrial excavators that rely on high mass to produce tractive forces to counteract the forces of excavation. IPEx is made up of several custom actuators that all need to be verified for their intended application. This paper focuses on the initial design, testing and modifications of three actuators: the mobility actuator, the shoulder actuator, and the excavation actuator. Each actuator was tested under four separate test profiles: ambient motor characterization, hot and cold motor characterization, accelerated life test (ALT), and concept of operations (ConOps) test. The motor characterization tests enabled derivation of torque equations for each actuator to estimate output torque without implementing sensors. The accelerated life tests were successful for each actuator and verified the motors’ ability to survive the mission. For the ConOps test, only the bucket drum actuator performed a complete ConOps without the need to restart the test. Overall, the first series of testing resulted in various failure modes and minor design alterations for each actuator. The test results, failure modes, and design alterations are highlighted within this paper. This paper focuses on discussing the mobility, excavation, and shoulder actuator design, testing principles, and results that qualified it as a TRL 5 system.} } - Creager, C., Breckenridge, J., Johnson, K., Oravec, H., Moreland, S., Sobey, A. and McBryan, E. (2025). Best Practices for the Testing of Planetary Roving Vehicle Mobility Systems and Tires
. NASA, 20250003470. Source
BibTeX
@techreport{creager2025best, title = {Best Practices for the Testing of Planetary Roving Vehicle Mobility Systems and Tires}, author = {Creager, Colin and Breckenridge, John and Johnson, Kyle and Oravec, Heather and Moreland, Scott and Sobey, Alexander and McBryan, Emily}, number = {20250003470}, institution = {NASA}, year = {2025}, url = {https://ntrs.nasa.gov/citations/20250003470}, abstract = {NASA has an extensive history of conducting mobility testing on planetary tires, rovers, and mobility subsystems. This paper contains a summary of the best practices and lessons learned from past test approaches, as well as from relevant test methodologies external to NASA, with a focus on tires and mobility systems. It is intended to be a resource for future planetary rover developments. This document, which will be released in two phases, serves two objectives: 1) compile the existing knowledge of mobility related testing within NASA; and 2) identify major gaps in mobility related test needs and suggest potential paths forward. This first release of the document (early 2025) captures information based on the authors’ existing knowledge and an abbreviated literature review. A more thorough version will be released in late 2025 and will include more information on test methods external to NASA, as well as additional lessons learned through further investigations. The Lunar Terrain Vehicle (LTV) is used as case study to help identify major test needs; however, this document is intended to be applicable to a wide range of potential missions. Though no current mobility standards exist for the testing of planetary tires and mobility subsystems, future motive is to utilize the information from this whitepaper to guide the development of NASA mobility test standards.} } - Kawamoto, H., Uchiyama, M., Cooper, B. L. and McKay, D. S. (2011). Mitigation of lunar dust on solar panels and optical elements utilizing electrostatic traveling-wave
. Journal of Electrostatics. Source
BibTeX
@article{kawamoto2011mitigation, title = {Mitigation of lunar dust on solar panels and optical elements utilizing electrostatic traveling-wave}, author = {Kawamoto, Haruo and Uchiyama, M. and Cooper, B. L. and McKay, D. S.}, journal = {Journal of Electrostatics}, volume = {69}, pages = {370-379}, year = {2011}, doi = {10.1016/j.elstat.2011.04.016} } - Jehn, M., Just, G. H., Sargeant, H. M., Long-Fox, J. and Britt, D. T. (2025). Implications of Lunar Simulant Geotechnical Properties on Testbed Experimentation and Engineering Analysis
. Space and Planetary Resources. Source
BibTeX
@article{jehn2025implications, title = {Implications of Lunar Simulant Geotechnical Properties on Testbed Experimentation and Engineering Analysis}, author = {Jehn, Marcus and Just, Gabriele H. and Sargeant, Hannah M. and Long-Fox, Jared and Britt, Daniel T.}, journal = {Space and Planetary Resources}, volume = {1}, pages = {5}, year = {2025}, doi = {10.1007/s44461-025-00002-7}, abstract = {Understanding the mechanical behavior of lunar regolith simulants is crucial for progressing engineering analysis in surface infrastructure design and testbed evaluation. This study provides a detailed geotechnical characterization of the Colorado School of Mines Lunar Highlands Type-Testbed simulants, including a new highland-type lunar simulant integrated into the Mines Lunar Surface Simulator testbed. It includes the determination of key geotechnical properties such as particle size distribution, density, compressibility, cohesion, friction angle, and particle shape, using standardized ASTM testing procedures. Key findings show that while particle size distribution similarities exist among the simulants and actual lunar regolith, there are significant differences in density-dependent mechanical behaviors such as shear strength, compressibility, and deformation responses. These results emphasize the complexity of simulant fidelity and its impact on testbed experiments when simulating mid-Technology Readiness Level environments. Additionally, we emphasize the importance of density-specific testing for evaluating both geotechnical properties and simulant performance. This work presents the first comprehensive publication of the full geotechnical profile of Colorado School of Mines highland simulants and highlights the importance of using multiple parameters beyond just particle size distribution to evaluate simulant fidelity. Future research will concentrate on characterizing testbed variability and assessing properties across different density states to improve the application of lunar simulants in engineering analysis and testbed experimentation.} }