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Space Robotics

Encoders and Resolvers

Position and velocity feedback devices selected by flown and qualified planetary and orbital robotics programs.

Both failures recorded below are contamination or noise at the sensor, not resolution. The IPEx resolver was removed from the design because it injected enough electrical noise to make the motor controller behave erratically [1][2]. The Apollo 15 attitude set control panel thumbwheel resolvers went out of tolerance because contamination built up between the slip rings and the resolvers [4]. A feedback device is a moving electrical contact in a dirty vacuum, and that is what determines whether it survives.

Feedback devices selected and flown

Section titled “Feedback devices selected and flown”
PartManufacturerUsed bySource
SS511ATHoneywellipex (all drive actuators)[1][2]
ResolverNot namedipex (Generation 1 prototype)[1][2]
DS-70Netzerrassor (bucket drum and shoulder actuators)[3]
EM1 optical quadrature encoder moduleUS Digitalrassor (all ten actuators)[3]
Odometer, one per traction driveNot namedapollo-lrv[4]
Thumbwheel resolversNot namedApollo command module[4]
Joint resolver with position sensorNot namedera[5]
Custom incremental encoderNot namedcuriosity (SAM)[6]

Ratings and qualification results

Section titled “Ratings and qualification results”
  • SS511AT, Honeywell. Hall effect sensor for commutation and velocity. Ratings: Three per motor. Combined with the high pole count of the ThinGap motor they meet the low-velocity control requirement without a separate position sensor[2]. Qualification: Ran through the whole KSC actuator qualification campaign including 6,547,036 input revolutions of accelerated life testing on the wheel actuator [1]. A second Hall device elsewhere on the vehicle, inside the Faulhaber radiator cover motor, could not be identified by part number, which the paper records as an open qualification item [1].
  • Resolver, vendor and part not named: a brushless resolver for speed and absolute position, carried on the Generation 1 prototype and removed before the Alpha build [1][2]. Ratings: Selected to give speed feedback at low motor speeds and absolute arm position across power cycles [1][2]. Qualification: Removed. During setup and tuning it produced enough electrical noise to make the motor controller react erratically, and showed noise and drift across the test range. Hall-only testing showed the resolver was unnecessary for speed control. Removing it lost absolute positioning after a power cycle, which was recovered with a homing routine plus continuous saving of arm position in software [1][2].
  • DS-70, Netzer. Single-turn absolute capacitive encoder, SSI output. Ratings: 19 bit angular resolution per 360 degrees, accuracy better than 10 millidegrees [3]. Qualification: Selected because absolute arm position had to be known without a homing move. The paper reports the sizing and the dual-loop position-over-velocity control it enables, not a life or environmental test [3].
  • EM1 optical quadrature encoder module, US Digital. Incremental optical encoder module. Ratings: 10,000 counts per revolution; read directly by Elmo Motion Control G-Sol WHI20/100 motor controllers closing PI position and velocity loops [3]. Qualification: Ground prototype. No environmental test result is published [3].
  • Odometer, one per traction drive, vendor not named. Pulse generator on the sealed wheel drive. Ratings: Nine pulses per wheel revolution into the navigation signal processing unit, behind an 80:1 harmonic drive and inside a traction drive hermetically sealed to 7.5 psia [4]. Qualification: Flew on Apollo 15, 16 and 17 as the odometry input to lunar surface dead-reckoning navigation [4].
  • Thumbwheel resolvers, vendor not named. Wire-wound resolvers on slip rings, in the command module attitude set control panel. Ratings: Nominal resistance varies by no more than 1 ohm in service [4]. Qualification: Flight anomaly. Postflight measurement found resistance increased from nominal by as much as 1000 ohms on all three axes, caused by contamination between the slip rings and the thumbwheel resolvers [4]. The measured change was still an order of magnitude too small to explain the roll-axis anomaly on its own, so two candidate relay failure modes, both also caused by contamination, remained open. Corrective action was to wipe the resolvers by rotating them several hundred revolutions, applied to the Apollo 16 and 17 panels [4].
  • Joint resolver with position sensor, vendor not named, built for the European Robotic Arm joint. Brushless resolver plus an independent optical joint angle sensor. Ratings: The resolver supplies instantaneous rotor position to the current-torque controller and enables ripple-free torque from the two-phase redundant winding. The Joint Position Sensor measures rotation at the joint exit axis and contains a redundant set of read stations, LEDs and signal processing [5]. Qualification: Flown on the ISS since 2021. The architecture separates motor commutation from joint angle knowledge, so a resolver fault does not by itself corrupt the joint angle used by the control electronics [5].
  • Custom incremental encoder, vendor not named, built for the SAM Sample Manipulation System carousel drive: an incremental encoder behind a 2500:1 reduction [6]. Ratings: 30,000 counts per revolution at the output of a 25:1 planetary and 100:1 harmonic drive combination. Qualification: The Sample Manipulation System recovers from an unexpected power loss through its feedback devices and control architecture, which is what the incremental device plus the mechanical latch scheme buys [6].

Deleting a resolver, and when that trade closes

Section titled “Deleting a resolver, and when that trade closes”

A resolver was deleted from a flight actuator design and replaced by Hall commutation plus a software homing routine. The IPEx Generation 1 prototype carried a resolver for speed feedback at low motor speeds and for absolute arm position across power cycles [1][2]. During setup and tuning it produced enough electrical noise to make the motor controller react erratically, and showed noise and drift across the test range. Testing in a Hall-sensor-only configuration then established that the resolver was unnecessary for speed control, because the high pole count of the ThinGap motors combined with the Hall sensors already met the low-velocity requirement [1]. The resolver was removed from every actuator on the grounds of the added complexity, mass, volume and wiring it entailed. The one capability lost, absolute positioning after a power cycle, was recovered by a homing routine plus continually saving the current arm position in software.

The trade only closes where a homing move is safe. RASSOR 2.0 states the opposite requirement, that absolute arm position had to be known without a homing move, and therefore keeps a Netzer DS-70 single-turn absolute encoder at 19 bit resolution per 360 degrees and better than 10 millidegree accuracy on its bucket drum and shoulder actuators [3]. The deciding parameter is not sensor performance but whether the mechanism can be moved blind at power-on.

Hall sensors and resolvers with a screening or flight result

Section titled “Hall sensors and resolvers with a screening or flight result”

Three further feedback devices carry a measured result. Two are Hall sensors screened against temperature and dose, and one is a flown resolver whose accuracy was calibrated on the ground [7][9].

PartManufacturerUsed bySource
SS41 bipolar Hall sensorHoneywellperseverance (maxon actuators)[7]
OMH3075S Hall effect sensorOptekGoddard gamma screen[8]
Suspension resolversNot namedcuriosity[9]

Ratings and qualification results

Section titled “Ratings and qualification results”
  • SS41 bipolar Hall sensor, Honeywell. Commutation sensor in the Mars 2020 maxon actuators. Ratings: usable from -100 to +200 C, well outside its published range, with performance deteriorating at both extremes [7]. Qualification: the flight lot was additionally screened with pre-conditioning, lead tinning, thermal cycling and destructive physical analysis, and 64 hours of gamma exposure to an absorbed 300 J/kg, equivalent to 30 krad, produced no failures [7]. The detent brake fitted to the same motor produced stray flux at this sensor and caused commutation switching errors until it was compensated, which is recorded on Motors.
  • OMH3075S Hall effect sensor, Optek. Commercial Hall effect sensor screened for the NASA Electronic Parts and Packaging program. Ratings: all parameters measured against specification [8]. Qualification: 40 krad(Si) at low dose rate with all parameters in specification, at the Goddard Space Flight Center gamma irradiator [8]. The campaign took no single-event data on this part.
  • Suspension resolvers, vendor not named, on the Curiosity rocker-bogie suspension. Ratings: sampled at 64 Hz [9]. Qualification: accuracy measured experimentally against an absolute encoder at 0.51 to 0.65 degrees [9]. The figure bounds the suspension angles used in slip and tilt estimation, not the drive actuator feedback.

A Hall sensor qualified against temperature and dose can still be defeated by a magnet fitted next to it, which is what the Mars 2020 detent brake did [7]. The screening envelope and the installed environment are separate qualification questions.

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. 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.}
}
  4. NASA Manned Spacecraft Center. (1971). Apollo 15 Mission Report . NASA Manned Spacecraft Center, MSC-05161. Source
    BibTeX
    @techreport{anon1971apollo,
  title = {Apollo 15 Mission Report},
  author = {{NASA Manned Spacecraft Center}},
  number = {MSC-05161},
  institution = {NASA Manned Spacecraft Center},
  year = {1971},
  url = {https://ntrs.nasa.gov/citations/19720021182},
  abstract = {A detailed discussion is presented of the Apollo 15 mission, which conducted exploration of the moon over longer periods, greater ranges, and with more instruments of scientific data acquisition than previous missions. The topics include trajectory, lunar surface science, inflight science and photography, command and service module performance, lunar module performance, lunar surface operational equipment, pilot's report, biomedical evaluation, mission support performance, assessment of mission objectives, launch phase summary, anomaly summary, and vehicle and equipment descriptions. The capability of transporting larger payloads and extending time on the moon were demonstrated. The ground-controlled TV camera allowed greater real-time participation by earth-bound personnel. The crew operated more as scientists and relied more on ground support team for systems monitoring. The modified pressure garment and portable life support system provided better mobility and extended EVA time. The lunar roving vehicle and the lunar communications relay unit were also demonstrated.}
}
  5. Cruijssen, H. J., Ellenbroek, M., Henderson, M., Petersen, H., Verzijden, P. and Visser, M. (2014). The European Robotic Arm: A High-Performance Mechanism Finally on its way to Space . Aerospace Mechanisms Symposium, NASA Goddard Space Flight Center, 20150004070. Source
    BibTeX
    @inproceedings{cruijssen2014european,
  title = {The European Robotic Arm: A High-Performance Mechanism Finally on its way to Space},
  author = {Cruijssen, H. J. and Ellenbroek, M. and Henderson, M. and Petersen, H. and Verzijden, P. and Visser, M.},
  booktitle = {Aerospace Mechanisms Symposium, NASA Goddard Space Flight Center},
  number = {20150004070},
  institution = {NASA},
  year = {2014},
  url = {https://ntrs.nasa.gov/citations/20150004070},
  abstract = {This paper describes the design and qualification of the European Robotic Arm (ERA), which is planned to be launched by the end of 2015. After years of changes, a shift of launcher and new loads, launch preparation is underway. The European Robotic Arm ERA has been designed and manufactured by Dutch Space and its subcontractors such as Astrium, SABCA and Stork with key roles for the mechanical aspects. The arm was originally designed to be launched by the STS (mounted on a Russian module for the ISS) in 2001. However, due to delays and the STS disaster, a shift was made to the Russian Proton rocket. ERA will be launched on the Multipurpose Laboratory Module (MLM). This module, which is now planned for launch to the ISS in 2015, will carry the ERA. The symmetrical design of the arm with a complete 3 degree-of-freedom wrist and general-purpose end effector on both sides, allows ERA to relocate on the station by grappling a new base point and releasing the old one, and move to different working locations.
}
}
  6. Mahaffy, P. R., Webster, C. R., Cabane, M., Conrad, P. G., Coll, P., Atreya, S. K., Arvey, R., Barciniak, M., Benna, M., Bleacher, L., Brinckerhoff, W. B., Eigenbrode, J. L., Carignan, D., Cascia, M., Chalmers, R. A., Dworkin, J. P., Errigo, T., Everson, P., Franz, H., Farley, R., Feng, S., Frazier, G., Freissinet, C., Glavin, D. P., Harpold, D. N., Hawk, D., Holmes, V., Johnson, C. S., Jones, A., Jordan, P., Kellogg, J., Lewis, J., Lyness, E., Malespin, C. A., Martin, D. K., Maurer, J., McAdam, A. C., McLennan, D., Nolan, T. J., Noriega, M., Pavlov, A. A., Prats, B., Raaen, E., Sheinman, O., Sheppard, D., Smith, J., Stern, J. C., Tan, F., Trainer, M., Ming, D. W., Morris, R. V., Jones, J., Gundersen, C., Steele, A., Wray, J., Botta, O., Leshin, L. A., Owen, T., Battel, S., Jakosky, B. M., Manning, H., Squyres, S., Navarro-González, R., McKay, C. P., Raulin, F., Sternberg, R., Buch, A., Sorensen, P., Kline-Schoder, R., Coscia, D., Szopa, C., Teinturier, S., Baffes, C., Feldman, J., Flesch, G., Forouhar, S., Garcia, R., Keymeulen, D., Woodward, S., Block, B. P., Arnett, K., Miller, R., Edmonson, C., Gorevan, S. and Mumm, E. (2012). The Sample Analysis at Mars Investigation and Instrument Suite . Space Science Reviews. Source
    BibTeX
    @article{mahaffy2012sample,
  title = {The Sample Analysis at Mars Investigation and Instrument Suite},
  author = {Mahaffy, Paul R. and Webster, Christopher R. and Cabane, Michel and Conrad, Pamela G. and Coll, Patrice and Atreya, Sushil K. and Arvey, Robert and Barciniak, Michael and Benna, Mehdi and Bleacher, Lora and Brinckerhoff, William B. and Eigenbrode, Jennifer L. and Carignan, Daniel and Cascia, Mark and Chalmers, Robert A. and Dworkin, Jason P. and Errigo, Therese and Everson, Paula and Franz, Heather and Farley, Rodger and Feng, Steven and Frazier, Gregory and Freissinet, Caroline and Glavin, Daniel P. and Harpold, Daniel N. and Hawk, Douglas and Holmes, Vincent and Johnson, Christopher S. and Jones, Andrea and Jordan, Patrick and Kellogg, James and Lewis, Jesse and Lyness, Eric and Malespin, Charles A. and Martin, David K. and Maurer, John and McAdam, Amy C. and McLennan, Douglas and Nolan, Thomas J. and Noriega, Marvin and Pavlov, Alexander A. and Prats, Benito and Raaen, Eric and Sheinman, Oren and Sheppard, David and Smith, James and Stern, Jennifer C. and Tan, Florence and Trainer, Melissa and Ming, Douglas W. and Morris, Richard V. and Jones, John and Gundersen, Cindy and Steele, Andrew and Wray, James and Botta, Oliver and Leshin, Laurie A. and Owen, Tobias and Battel, Steve and Jakosky, Bruce M. and Manning, Heidi and Squyres, Steven and Navarro-González, Rafael and McKay, Christopher P. and Raulin, Francois and Sternberg, Robert and Buch, Arnaud and Sorensen, Paul and Kline-Schoder, Robert and Coscia, David and Szopa, Cyril and Teinturier, Samuel and Baffes, Curt and Feldman, Jason and Flesch, Greg and Forouhar, Siamak and Garcia, Ray and Keymeulen, Didier and Woodward, Steve and Block, Bruce P. and Arnett, Ken and Miller, Ryan and Edmonson, Charles and Gorevan, Stephen and Mumm, Erik},
  journal = {Space Science Reviews},
  volume = {170},
  pages = {401--478},
  year = {2012},
  doi = {10.1007/s11214-012-9879-z},
  abstract = {The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover’s robotic arm.}
}
  7. Loschiavo, M., Phillips, R., Mikhaylov, R. and Braunschweig, L. (2020). Mars 2020 Maxon Commercial Motor Development from COTS to Flight Qualified Motors, Gearbox, and Detent Brake: Issues Overcome and Lessons Learned . Aerospace Mechanisms Symposium. Source
    BibTeX
    @inproceedings{loschiavo2020mars,
  title = {Mars 2020 Maxon Commercial Motor Development from COTS to Flight Qualified Motors, Gearbox, and Detent Brake: Issues Overcome and Lessons Learned},
  author = {Loschiavo, Michael and Phillips, Robin and Mikhaylov, Rebecca and Braunschweig, Lynn},
  booktitle = {Aerospace Mechanisms Symposium},
  publisher = {JPL Open Repository},
  year = {2020},
  url = {https://dataverse.jpl.nasa.gov/dataset.xhtml?persistentId=hdl:2014/52357}
}
  8. Topper, A. D., Lauenstein, J.-M., Wilcox, E. P., Berg, M. D., Campola, M. J., Casey, M. C., Wyrwas, E. J., O'Bryan, M. V., Carstens, T. A., Fedele, C. M., Forney, J. D., Kim, H. S., Osheroff, J. M., Phan, A. M., Chaiken, M. F., Cochran, D. J., Pellish, J. A. and Majewicz, P. J. (2020). NASA Goddard Space Flight Center's Compendium of Radiation Effects Test Results . IEEE Radiation Effects Data Workshop. Source
    BibTeX
    @inproceedings{topper2020nasa,
  title = {NASA Goddard Space Flight Center's Compendium of Radiation Effects Test Results},
  author = {Topper, Alyson D. and Lauenstein, Jean-Marie and Wilcox, Edward P. and Berg, Melanie D. and Campola, Michael J. and Casey, Megan C. and Wyrwas, Edward J. and O'Bryan, Martha V. and Carstens, Thomas A. and Fedele, Caroline M. and Forney, James D. and Kim, Hak S. and Osheroff, Jason M. and Phan, Anthony M. and Chaiken, Max F. and Cochran, Donna J. and Pellish, Jonathan A. and Majewicz, Peter J.},
  booktitle = {IEEE Radiation Effects Data Workshop},
  pages = {1--12},
  year = {2020},
  doi = {10.1109/redw51883.2020.9325841},
  abstract = {Total ionizing dose, displacement damage dose, and single event effects testing were performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include FETs, flash memory, FPGAs, optoelectronics, digital, analog, and bipolar devices.}
}
  9. Rankin, A., Maimone, M., Biesiadecki, J., Patel, N., Levine, D. and Toupet, O. (2021). Mars Curiosity Rover Mobility Trends During the First Seven Years . Journal of Field Robotics, 5. Source
    BibTeX
    @article{rankin2021mars,
  title = {Mars Curiosity Rover Mobility Trends During the First Seven Years},
  author = {Rankin, Arturo and Maimone, Mark and Biesiadecki, Jeffrey and Patel, Nikunj and Levine, Dan and Toupet, Olivier},
  journal = {Journal of Field Robotics},
  volume = {38},
  number = {5},
  pages = {759--800},
  year = {2021},
  doi = {10.1002/rob.22011},
  abstract = {Abstract NASA's Mars Science Laboratory (MSL) Curiosity rover landed on Mars on August 6, 2012. In the 7 years between landing and August 6, 2019 (sol 2488), Curiosity has driven 21,318.5 m over a variety of terrain types and slopes, employing multiple drive modes with varying amounts of onboard autonomy. Curiosity's drive distances each sol have ranged from its shortest drive of 2.6 cm to its longest drive of 142.5 m, with an average drive distance of 28.9 m. Real‐time human intervention is not possible during Curiosity's drives due to the latency in uplinking commands and downlinking telemetry. Instead, the operations team relies on Curiosity's fault protection, autonomous navigation, and visual odometry software to keep the rover safe during drives. During its first 7 years on Mars, Curiosity has attempted 738 drives. While 622 drives ran to completion, 116 drives were prevented or stopped early by Curiosity's fault protection software. The primary risks to mobility success have been wheel damage, wheel entrapment, progressive wheel sinkage, and the potential for hardware or cable failures that result in an inability to command one or more steer or drive actuators. In this paper, we describe Curiosity's mobility subsystem, mobility trends over the first 21.3 km of the mission, operational aspects of mobility fault protection, risks to continued mobility success, and risk mitigation strategies.}
}