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Space Robotics

Connectors, Seals and Materials

Seals, barriers, fasteners and structural materials selected by flown and qualified planetary robotics programs, with the dust and vacuum test results published for them.

The strongest result in this class is negative. IPEx removed the electrical charging connector entirely and charges through an antenna carried on the radiator cover, because a dust-tolerant electrical connector is the component most likely to fail in a regolith environment [2]. Where a rotating interface cannot be removed, the IPEx answer is a three-stage stack: labyrinth outermost, then felt, then a PTFE lip seal [1][2].

Seals, fasteners and materials selected and flown

Section titled “Seals, fasteners and materials selected and flown”
PartManufacturerUsed bySource
Nomex felt sealNot namedipex (all drive actuators)[1][2]
Spring-loaded PTFE rotary sealNot namedspirit, opportunity (arm)[3]
Aeroflex rotary shaft sealAeroflexspirit, opportunity (steering)[3]
Beta clothNot namedBoots and bellows over mechanisms[3]
Chromel-R fabric, RTV-630 facingNot namedApollo suit boots and gloves[4]
Velcro hook and pile on KaptonNot namedApollo 17 receiver thermal bag[5]
A286 screws, Nitronic 60 insertsNot namedipex[1][2]
Zirconia and silicon nitride ballsNot namedLunar mechanisms, candidate[3]
Sapphire window, fused silica opticsOptimaxperseverance (SHERLOC ACI)[7]

Ratings and qualification results

Section titled “Ratings and qualification results”
  • Nomex felt seal, vendor not named. Three-stage rotary dust seal: a labyrinth path, then felt, then a PTFE lip. Ratings: Layered outward from a PTFE lip seal to a Nomex felt seal to a labyrinth path [1][2]. Qualification: Tested in dirty vacuum under the TC4 test-as-you-fly profile with a dust cup conveying simulant over the rotating output. A single felt seal gave sufficient protection in the worst case, with minimal dust found beyond it. A large quantity of dust penetrated the labyrinth stage, attributed to the test submerging the lower section of the running actuator rather than to the seal design [1]. Measured seal drag torque across the Generation 1 campaign peaked at 0.03 N m, under one percent of the overall load [2].
  • Spring-loaded PTFE rotary seal, vendor not named: a spring-energized lip seal for outer diameters above about 1.5 inch, flown on the MER Instrument Deployment Device [3]. Ratings: Flight heritage on the MER arm; tested in vacuum in the presence of lunar simulant [3]. Qualification: Durable and effective in simulant vacuum testing, and scored joint highest of three seal types in a weighted trade study, Table 3. Long-term stability under lunar temperature extremes and radiation is recorded as unresolved [3].
  • Aeroflex rotary shaft seal, Aeroflex. Dry running rotary shaft seal, on the MER wheel steering actuators. Ratings: Simple mechanism with no lubricant [3]. Qualification: Successfully limited regolith ingress in vacuum simulant testing. Requires high machining tolerances, is susceptible to misalignment during installation, and is affected by vibration; lunar material selection is unresolved [3].
  • Beta cloth, vendor not named. Fiberglass fabric used as a flexible dust barrier in boots and bellows over lunar mechanisms. Ratings: Compared against thermoplastic polyurethane and Tyvek for the same application, scored on mass per square meter, complexity, TRL, manufacturability into a boot, durability and 40 to 400 K temperature sensitivity [3]. Qualification: Scored highest of the three barrier materials in the weighted trade, the gap driven by higher TRL and by durability and effectiveness. The result is a trade score, Table 5, not a life test [3].
  • Chromel-R fabric, RTV-630 facing, vendor not named. Abrasion-resistant metallic fabric in the extravehicular mobility unit boots and gloves. Ratings: Woven into the boots and gloves; RTV-630 used for soles and finger tips [4]. Qualification: Introduced in flight because the super beta cloth outer covering was not abrasion resistant against sharp lunar rock. The rest of the dust control scheme did not work: a single nylon bristle brush removed coarse grains but not fines and may have transferred nearly as much dust as it removed, wrist bearings and rotational connectors had only fabric covers that were not effective, and from Apollo 15 Velcro-attached dust covers were added to the front connectors [4].
  • Velcro hook and pile on Kapton, vendor not named. Fastener system bonded with polyurethane FR-127 A and B, on the Apollo 17 lunar surface receiver thermal bag. Ratings: Pile pads bonded to the Kapton bag, hook straps bonded to the Kapton flaps [5]. Qualification: Flight failure. Both flap bonds had failed before the end of the first EVA, letting dust settle on the mirror surface under both flaps. The pads came away leaving no adhesive trace on the Kapton. FR-127 A and B remains recommended for bonding Velcro to Kapton; the failure was attributed to bonding preparation and procedure, with mixing, timing and freedom from surface contamination named as the controlled parameters [5].
  • A286 screws, Nitronic 60 inserts, vendor not named: a standard 4-40 fastener set with locking helical inserts [2]. Ratings: Used throughout the vehicle for commonality, with 2-56 fasteners as a deliberate exception at the harmonic drive flex cup and wave generator. Qualification: Carried through the KSC actuator qualification campaign, including the accelerated life test that ran the wheel actuator to 6,547,036 input revolutions and repeated disassembly and inspection between runs [1][2].
  • Zirconia and silicon nitride balls, vendor not named. Ceramic rolling elements as a dust-tolerance strategy, a candidate for lunar surface mechanisms. Ratings: Very high hardness against abrasion, and both run dry, which removes lubricant from the failure set in lunar vacuum [3]. Qualification: Scored highest of four dust-tolerant bearing types in a weighted trade, with a clear gap to stainless steel and to hybrid superconducting magnetic bearings, driven by durability and dry running. The result is a trade score, Table 9 [3].
  • Sapphire window, fused silica optics, optics by Optimax. Fluorescence-free optical train of uncoated UV-grade fused silica and magnesium fluoride behind a sapphire window. Ratings: Four-element telecentric objective behind a sapphire window, all elements uncoated, made from UV-grade fused silica or fluorescence-free magnesium fluoride; the camera lens group moves on a linear rail [7]. Qualification: Materials were chosen to be fluorescence-free because the instrument measures deep ultraviolet fluorescence and Raman scatter, so any optic that fluoresces becomes a background signal. The dust cover is solid aluminum and opaque, carrying the internal AlGaN calibration target on its inner face [7].

Fastener and structure notes

Section titled “Fastener and structure notes”

RASSOR 2.0 records a manufacturing result rather than a materials one [6]. The shoulder actuator housings were 3D printed in titanium with extra material left on the bearing, stator, rotor and sealing faces for later machining. With no printed datum to work from, the machinist had to build fixtures for each of six parts and assume an axis of revolution in each, to bring the motor, bearings and harmonic drive coaxial [6]. Where a printed housing carries a bearing bore and a seal face, the print does not remove the machining operation.

Seal and surface materials with a measured or normative limit

Section titled “Seal and surface materials with a measured or normative limit”

The rows below are the level at which a seal, a connector or a surface coating stops meeting its requirement. Solder joints, package interconnects, platings and the printed wiring they sit on are on Packaging and Board Reliability.

PartManufacturerUsed bySource
Sample tube seal SN282Not namedperseverance[8]
TR01447 Kapton with KevlarNot namedviper (dust sock)[9]
Cr3C2-NiCr HVOF coatingNot namedLangley Taber abrasion[10]
M83513-03-E03C connectorGlenairastrobee payload interface[11]

Ratings and requirements

Section titled “Ratings and requirements”
  • Sample tube seal SN282. Ratings: one tube, measured by static-mode noble gas mass spectrometry over accumulations of 23 to 29 hours [8]. Qualification: helium leak rate 1.7e-15 scc/s at -51 C and 1.4e-13 scc/s at +42 C, over eight average run temperatures on that one tube, rising with temperature and linear against inverse absolute temperature [8]. The demonstrated range is -51 to +42 C and nothing outside it.
  • TR01447 Kapton with Kevlar, heavyweight Kevlar reinforcement, selected as the VIPER dust sock baseline. Ratings: Martindale abrasion testing at the Johnson Space Center softgoods laboratory [9]. Qualification: no increase in air permeation, 7.8 percent thickness loss and 1.2 percent weight loss at 100 percent completion of the run [9]. The candidate MO01503 reached 200 percent completion but lost 23.1 percent of thickness and 3.9 percent of weight, and DE355 lost 49.5 and 21.7 percent, so the selection traded abrasion endurance for retained thickness.
  • Cr3C2-NiCr HVOF coating on aluminum 6061, as deposited and unpolished [10]. Ratings: ASTM D4060 Taber abrasion with CS-17 wheels, eddy current thickness at 400, 1200 and 5000 cycles. Qualification: just under 2 micrometers of thickness lost after 5000 cycles, the best of seven commercial coatings, with mass loss too small across every composition to compute a wear index [10]. Tribaloy T-800 and Cr3C2 coatings lost under 5 micrometers, an air plasma sprayed alumina-titania coating lost over 20 and also had the highest as-processed roughness at 1.55 micrometers Ra, and an air plasma sprayed yttria-stabilized zirconia coating gave a wear index of 9.20 mg per 1000 cycles, roughly twice the alumina rate. Under a 20 kHz sonic wand screen with LHS-1D milled highland simulant, the alumina, Cr3C2-NiCr and Tribaloy T-800 coatings retained the least residual dust of the seven, judged semi-quantitatively from optical images [10].
  • M83513-03-E03C connector, Glenair. Thirty-one pin blind mate connector carrying the Astrobee payload interface. Ratings: 14.4 V at a 3 A limit, with three USB 2.0 data pinouts routed to different processors [11]. Qualification: no environmental or life result is published for it.

Aluminum against itself is the worst uncoated cold-welding pair measured in the corpus, at 1775 mN of adhesion under vacuum impact, above titanium [12]; the full set of contact-pair results is on Bearings and Lubrication.

References

  1. 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.}
}
  2. 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.}
}
  3. 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.}
}
  4. Gaier, J. R. (2005). The Effects of Lunar Dust on EVA Systems During the Apollo Missions . NASA Glenn Research Center, NASA/TM-2005-213610, 20050160460. Source
    BibTeX
    @techreport{gaier2005effects,
  title = {The Effects of Lunar Dust on EVA Systems During the Apollo Missions},
  author = {Gaier, James R.},
  number = {NASA/TM-2005-213610, 20050160460},
  institution = {NASA Glenn Research Center},
  year = {2005},
  url = {https://ntrs.nasa.gov/citations/20050160460},
  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.}
}
  5. MIssion Evaluation Team. (1973). Apollo 17 Mission Report . NASA, NASA-TM-. Source
    BibTeX
    @techreport{anon1973apollo,
  title = {Apollo 17 Mission Report},
  author = {{MIssion Evaluation Team}},
  number = {NASA-TM-},
  institution = {NASA},
  year = {1973},
  url = {https://ntrs.nasa.gov/citations/19730015117},
  abstract = {Operational and engineering aspects of the Apollo 17 mission are outlined. The vehicle configuration was similar to those of Apollo 15 and 16. There were significant differences in the science payload for Apollo 17 and spacecraft hardware differences and experiment equipment are described. The mission achieved a landing in the Taurus-Littrow region of the moon and returned samples of the pre-Imbrium highlands and young craters.}
}
  6. 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 . Earth and Space, 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 = {Earth and Space},
  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.}
}
  7. Bhartia, R., Beegle, L. W., DeFlores, L., Abbey, W., Razzell Hollis, J., Uckert, K., Monacelli, B., Edgett, K. S., Kennedy, M. R., Sylvia, M., Aldrich, D., Anderson, M., Asher, S. A., Bailey, Z., Boyd, K., Burton, A. S., Caffrey, M., Calaway, M. J., Calvet, R., Cameron, B., Caplinger, M. A., Carrier, B. L., Chen, N., Chen, A., Clark, M. J., Clegg, S., Conrad, P. G., Cooper, M., Davis, K. N., Ehlmann, B., Facto, L., Fries, M. D., Garrison, D. H., Gasway, D., Ghaemi, F. T., Graff, T. G., Hand, K. P., Harris, C., Hein, J. D., Heinz, N., Herzog, H., Hochberg, E., Houck, A., Hug, W. F., Jensen, E. H., Kah, L. C., Kennedy, J., Krylo, R., Lam, J., Lindeman, M., McGlown, J., Michel, J., Miller, E., Mills, Z., Minitti, M. E., Mok, F., Moore, J., Nealson, K. H., Nelson, A., Newell, R., Nixon, B. E., Nordman, D. A., Nuding, D., Orellana, S., Pauken, M., Peterson, G., Pollock, R., Quinn, H., Quinto, C., Ravine, M. A., Reid, R. D., Riendeau, J., Ross, A. J., Sackos, J., Schaffner, J. A., Schwochert, M., Shelton, M. O., Simon, R., Smith, C. L., Sobron, P., Steadman, K., Steele, A., Thiessen, D., Tran, V. D., Tsai, T., Tuite, M., Tung, E., Wehbe, R., Weinberg, R., Weiner, R. H., Wiens, R. C., Williford, K., Wollonciej, C., Wu, Y.-H., Yingst, R. A. and Zan, J. (2021). Perseverance's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation . Space Science Reviews, 58. Source
    BibTeX
    @article{bhartia2021perseverance,
  title = {Perseverance's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation},
  author = {Bhartia, Rohit and Beegle, Luther W. and DeFlores, Lauren and Abbey, William and Razzell Hollis, Joseph and Uckert, Kyle and Monacelli, Brian and Edgett, Kenneth S. and Kennedy, Megan R. and Sylvia, Margarite and Aldrich, David and Anderson, Mark and Asher, Sanford A. and Bailey, Zachary and Boyd, Kerry and Burton, Aaron S. and Caffrey, Michael and Calaway, Michael J. and Calvet, Robert and Cameron, Bruce and Caplinger, Michael A. and Carrier, Brandi L. and Chen, Nataly and Chen, Amy and Clark, Matthew J. and Clegg, Samuel and Conrad, Pamela G. and Cooper, Moogega and Davis, Kristine N. and Ehlmann, Bethany and Facto, Linda and Fries, Marc D. and Garrison, Dan H. and Gasway, Denine and Ghaemi, F. Tony and Graff, Trevor G. and Hand, Kevin P. and Harris, Cathleen and Hein, Jeffrey D. and Heinz, Nicholas and Herzog, Harrison and Hochberg, Eric and Houck, Andrew and Hug, William F. and Jensen, Elsa H. and Kah, Linda C. and Kennedy, John and Krylo, Robert and Lam, Johnathan and Lindeman, Mark and McGlown, Justin and Michel, John and Miller, Ed and Mills, Zachary and Minitti, Michelle E. and Mok, Fai and Moore, James and Nealson, Kenneth H. and Nelson, Anthony and Newell, Raymond and Nixon, Brian E. and Nordman, Daniel A. and Nuding, Danielle and Orellana, Sonny and Pauken, Michael and Peterson, Glen and Pollock, Randy and Quinn, Heather and Quinto, Claire and Ravine, Michael A. and Reid, Ray D. and Riendeau, Joe and Ross, Amy J. and Sackos, Joshua and Schaffner, Jacob A. and Schwochert, Mark and Shelton, Molly O and Simon, Rufus and Smith, Caroline L. and Sobron, Pablo and Steadman, Kimberly and Steele, Andrew and Thiessen, Dave and Tran, Vinh D. and Tsai, Tony and Tuite, Michael and Tung, Eric and Wehbe, Rami and Weinberg, Rachel and Weiner, Ryan H. and Wiens, Roger C. and Williford, Kenneth and Wollonciej, Chris and Wu, Yen-Hung and Yingst, R. Aileen and Zan, Jason},
  journal = {Space Science Reviews},
  volume = {217},
  number = {58},
  year = {2021},
  doi = {10.1007/s11214-021-00812-z},
  abstract = {Abstract The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm-mounted instrument on NASA’s Perseverance rover. SHERLOC has two primary boresights. The Spectroscopy boresight generates spatially resolved chemical maps using fluorescence and Raman spectroscopy coupled to microscopic images (10.1 μm/pixel). The second boresight is a Wide Angle Topographic Sensor for Operations and eNgineering (WATSON); a copy of the Mars Science Laboratory (MSL) Mars Hand Lens Imager (MAHLI) that obtains color images from microscopic scales (∼13 μm/pixel) to infinity. SHERLOC Spectroscopy focuses a 40 μs pulsed deep UV neon-copper laser (248.6 nm), to a ∼100 μm spot on a target at a working distance of ∼48 mm. Fluorescence emissions from organics, and Raman scattered photons from organics and minerals, are spectrally resolved with a single diffractive grating spectrograph with a spectral range of 250 to ∼370 nm. Because the fluorescence and Raman regions are naturally separated with deep UV excitation (<250 nm), the Raman region ∼ 800 – 4000 cm −1 (250 to 273 nm) and the fluorescence region (274 to ∼370 nm) are acquired simultaneously without time gating or additional mechanisms. SHERLOC science begins by using an Autofocus Context Imager (ACI) to obtain target focus and acquire 10.1 μm/pixel greyscale images. Chemical maps of organic and mineral signatures are acquired by the orchestration of an internal scanning mirror that moves the focused laser spot across discrete points on the target surface where spectra are captured on the spectrometer detector. ACI images and chemical maps (< 100 μm/mapping pixel) will enable the first Mars in situ view of the spatial distribution and interaction between organics, minerals, and chemicals important to the assessment of potential biogenicity (containing CHNOPS). Single robotic arm placement chemical maps can cover areas up to 7x7 mm in area and, with the < 10 min acquisition time per map, larger mosaics are possible with arm movements. This microscopic view of the organic geochemistry of a target at the Perseverance field site, when combined with the other instruments, such as Mastcam-Z, PIXL, and SuperCam, will enable unprecedented analysis of geological materials for both scientific research and determination of which samples to collect and cache for Mars sample return.}
}
  8. Osterhout, J. T., Farley, K. A., Wadhwa, M., Treffkorn, J. and Kulczycki, E. (2024). Helium Leak Rate Measurements of Flight-like Mars 2020 Sample Tubes . Astrobiology, 1. Source
    BibTeX
    @article{osterhout2024helium,
  title = {Helium Leak Rate Measurements of Flight-like Mars 2020 Sample Tubes},
  author = {Osterhout, Jeffrey T. and Farley, Kenneth A. and Wadhwa, Meenakshi and Treffkorn, Jonathan and Kulczycki, Eric},
  journal = {Astrobiology},
  volume = {24},
  number = {1},
  pages = {36--43},
  year = {2024},
  doi = {10.1089/ast.2023.0002},
  abstract = {The sample tubes on board NASA's Perseverance rover are designed to contain rocks, regolith, and atmospheric gases and are hermetically sealed on the surface of Mars to minimize sample loss, alteration, and contamination. Following a robust testing program during mission development, it was determined that the helium (He) leak rates of flight-like sample tubes sealed under a range of conditions were typically no greater than ∼10 −10 standard cubic centimeters per second (scc/s); leak rates below this value could not be measured since this is the detection limit of commercially available He leak detectors. This limit was adequate to meet mission requirements. However, some scientific objectives could be compromised by sample tube leak rates even below 10 −10 scc/s, thus motivating a more sensitive technique for establishing leak rates. This study investigated He leak rates on six flight-like sample tubes using a static mode mass spectrometer. Room temperature He leak rates of the six sample tubes ranged from ∼8.8 × 10 −17 to ∼4.6 × 10 −14 scc/s. One sample tube was analyzed at eight different temperatures, ranging from -51°C to +42°C, and yielded He leak rates correlated with temperature that varied from ∼1.7 × 10 −15 to ∼1.4 × 10 −13 scc/s, respectively. Our results confirm and extend previous findings demonstrating that the Mars 2020 sample tube seals are likely to be very leak-tight, with leak rates <10 −13 scc/s. These leak rates are sufficiently low that the impact of gas egress or ingress is expected to be negligible.}
}
  9. 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.}
}
  10. Wiesner, V. L., Wohl, C. J., King, G. C., Gordon, K. L., Das, L. and Hernandez, J. J. (2023). Protective Coatings for Lunar Dust Tolerance . NASA, NASA/TM-20230003195. Source
    BibTeX
    @techreport{wiesner2023protective,
  title = {Protective Coatings for Lunar Dust Tolerance},
  author = {Wiesner, Valerie L. and Wohl, Christopher J. and King, Glen C. and Gordon, Keith L. and Das, Lopamudra and Hernandez, Jonathan J.},
  number = {NASA/TM-20230003195},
  institution = {NASA},
  year = {2023},
  url = {https://ntrs.nasa.gov/citations/20230003195},
  abstract = {Materials capable of withstanding the harsh lunar environment are critically needed to
support long duration, sustainable missions on the Moon’s surface. Lunar dust significantly
threatens the durability and reusability of components and vehicles due to possessing a fine, jagged morphology and highly abrasive nature. These characteristics result in the particles eroding, adhering and/or embedding onto component surfaces and into device confined geometries (e.g., gear housing, interlocking systems, etc.) potentially leading to premature failure. The aim of this study is to identify and characterize wear-resistant commercial-off-the-shelf (COTS) materials, including advanced ceramics, for use as protective coatings to minimize abrasion and adhesion caused by lunar dust. Preliminary testing that mimics various aspects of lunar dust degradation, such as abrasive wear and adhesion, suggests that COTS ceramic coatings can improve lunar dust tolerance and protect underlying metallic substrates.}
}
  11. Park, I.-W., Smith, T., Sanchez, H., Wong, S. W., Piacenza, P. and Ciocarlie, M. (2017). Developing a 3-DOF Compliant Perching Arm for a Free-Flying Robot on the International Space Station . IEEE International Conference on Advanced Intelligent Mechatronics (AIM). Source
    BibTeX
    @inproceedings{park2017developing,
  title = {Developing a 3-DOF Compliant Perching Arm for a Free-Flying Robot on the International Space Station},
  author = {Park, In-Won and Smith, Trey and Sanchez, Hugo and Wong, Sze Wun and Piacenza, Pedro and Ciocarlie, Matei},
  booktitle = {IEEE International Conference on Advanced Intelligent Mechatronics (AIM)},
  pages = {1135-1141},
  year = {2017},
  doi = {10.1109/aim.2017.8014171},
  abstract = {This paper presents the design and control of the 3-DOF compliant perching arm for the free-flying Astrobee robots that will operate inside the International Space Station (ISS). The robots are intended to serve as a flexible platform for future guest scientists to use for zero-gravity robotics research—thus, the arm is designed to support manipulation research. It provides a 1-DOF underactuated tendon-driven gripper capable of enveloping a range of objects of different shapes and sizes. Co-located RGB camera and LIDAR sensors provide perception. The Astrobee robots will be capable of grasping each other in flight, to simulate orbital capture scenarios. The arm's end-effector module is swappable on-orbit, allowing guest scientists to add upgraded grippers, or even additional arm degrees of freedom. The design of the arm balances research capabilities with Astrobee's operational need to perch on ISS handrails to reduce power consumption. Basic arm functioning and grip strength were evaluated using an integrated Astrobee prototype riding on a low-friction air bearing.}
}
  12. Merstallinger, A., Semerad, E. and Dunn, B. D. (2003). Influence of Coatings and Alloying on Cold Welding due to Impact and Fretting . European Space Mechanisms and Tribology Symposium. Source
    BibTeX
    @inproceedings{merstallinger2003cold,
  title = {Influence of Coatings and Alloying on Cold Welding due to Impact and Fretting},
  author = {Merstallinger, A. and Semerad, E. and Dunn, B. D.},
  booktitle = {European Space Mechanisms and Tribology Symposium},
  year = {2003},
  url = {https://www.esmats.eu/esmatspapers/pastpapers/pdfs/2003/merstallinger.pdf}
}