Space Mechanisms Technology Workshop

NASA/CP—2002-211882

September 2002
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September 2002

National Aeronautics and

Space Administration

Glenn Research Center

Proceedings of a conference held at and sponsored by

NASA Glenn Research Center

Cleveland, Ohio

May 14, 2002

Space Mechanisms Technology Workshop

NASA/CP—2002-211882
Acknowledgments

There were many people whose contributions made this workshop possible. It started with the organizing

committee: Robert Fusaro (now retired), James Zakrajsek, Rebecca Kwiat, Wilfredo Morales, Mark Siebert, and

Fred Oswald. Our invited speakers made an interesting workshop possible: Fred Crosno, Robert Fusaro, Lois

Gschwender, Geoffrey Landis, Wilfredo Morales, Fred Oswald, Frank Ruhle, Mark Siebert, Scott Starin, William

(Red) Whittaker and Jim Zakrajsek. Finally, we acknowledge the participation by our guests. They really made the

Workshop a success.

Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

Available electronically at http://gltrs.grc.nasa.gov

The Aerospace Propulsion and Power Program at

NASA Glenn Research Center sponsored this work.
NASA/CP—2002-211882 iii

TABLE OF CONTENTS

Summary............................................................................................................................................................................ 1

Introduction ....................................................................................................................................................................... 1

Overview of Glenn Mechanical Components Branch Research ....................................................................................... 1

Crossing Mars: Past and Future Missions to a Cold, Dry Desert ...................................................................................... 8

The Pathfinder Mission and Landing on Mars ........................................................................................................... 9

Six Wheels on Soil! .................................................................................................................................................... 9

Future Missions to Mars ........................................................................................................................................... 11

References ................................................................................................................................................................ 13

Robots in the Planetary Cold ........................................................................................................................................... 13

Candidate Coatings and Dry Traction Drives for Planetary Vehicles ............................................................................. 28

Fresh Ideas for Lubricants, Thinking Out of the Box...................................................................................................... 39

Using Condensed Gasses and Novel Liquids for Lubrication on the Martian Surface ................................................... 51

Passive Magnetic Bearing Development ......................................................................................................................... 55

Eddy Current Damper for Cryogenic Applications ......................................................................................................... 70

NASA/CP2002-211882 1 

Summary 

The Mechanical Components Branch at NASA Glenn Research Center hosted a 

workshop on Tuesday, May 14, 2002 to discuss space mechanisms technology. The theme for 

this workshop was “Working in the Cold,” a focus on space mechanisms that must operate at low 

temperatures. We define “cold” as below –60 °C (210K), such as would be found near the 

equator of Mars. However, we are also concerned with much colder temperatures such as in 

permanently dark craters of the Moon (about 40K). 

Introduction

This was the second in a planned series of space mechanisms technology workshops 

sponsored by the Mechanical Components Branch at NASA Glenn Research Center. The 

previous workshop in November 2000 considered space drives, mechanical transmissions that 

perform as speed reducers to match the high speed, low torque output, typical of electric motors, 

to the low speed, high torque required to operate machinery. This workshop focused on space 

mechanisms that must operate at low temperatures. We define “cold” as below –60 °C (210K), 

such as would be found near the equator of Mars. However, we are also concerned with much 

colder temperatures such as in permanently dark craters of the Moon (about 40K). 

These low temperatures present challenges for mechanisms design. At extreme 

temperatures, conventional liquid lubricants (including grease) may not be feasible, therefore 

either solid lubricants must be used, provision must be made to heat lubricants, or some 

unconventional lubricant may be considered. The goal is to identify the problems caused by 

these conditions and to project what resources will be needed to support future missions. 

This report summarizes the nine presentations on space mechanisms technology given at 

the workshop. 

Overview of Glenn Mechanical Components Branch Research

Mr. James Zakrajsek, chief of the Mechanical Components Branch, gave an overview of 

research conducted by the branch. Branch members perform basic research on mechanical 

components and systems, including gears and bearings, turbine seals, structural and thermal 

barrier seals, and space mechanisms. The research is focused on propulsion systems for present 

and advanced aerospace vehicles. 

For rotorcraft and conventional aircraft, we conduct research to develop technology 

needed to enable the design of low noise, ultra safe geared drive systems. We develop and 

validate analytical models for gear crack propagation, gear dynamics and noise, gear diagnostics, 

bearing dynamics, and thermal analyses of gear systems using experimental data from various 

component test rigs. 

In seal research we develop and test advanced turbine seal concepts to increase efficiency 

and durability of turbine engines. We perform experimental and analytical research to develop 

advanced thermal barrier seals and structural seals for current and next generation space vehicles. 
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Our space mechanisms research involves fundamental investigation of lubricants, 

materials, components and mechanisms for deep space and planetary environments. 
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Crossing Mars: Past and Future Missions to a Cold, Dry Desert 

Dr. Geoffrey A. Landis of the Photovoltaics and Space Environment Effects Branch 

presented an overview of recent discoveries about the environment of Mars. He covered 

missions from the 1966 Mariner IV that returned those first grainy close-up pictures of Mars 

showing an ancient cratered terrain to the Mars Odyssey mission with its tantalizing evidence of 

recent water flows on Mars. 

Mars is one of the most interesting planets in the solar system, featuring enormous 

canyons, giant volcanoes, and indications that, early in its history, it might have had rivers and 

perhaps even oceans. Five years ago, in July of 1997, the Pathfinder mission landed on Mars, 

bringing with it the microwave-oven sized Sojourner rover to wander around on the surface and 

analyze rocks. Pathfinder is only the first of an armada of spacecraft that will examine Mars 

from the pole to the equator in the next decade, culminating (someday, we hope!) with a mission 

to bring humans to Mars. 

Mars is the next planet out from the Sun, so it gets a little bit less sunlight than we do, 

and so it is a cool planet. Mars is a bit smaller than the Earth. The first thing you notice when 

you look at it is that it's a very red planet -actually more of a muddy orange color, but it’s much 

redder than the Earth, which is why they call it the red planet. 

The fact that we think of it as being a small planet is a little bit misleading. In fact, the 

land area of Mars is greater than the entire land area of the planet Earth. It's really a big place. 

There's a lot to explore on the planet Mars. 

You can see Mars from the Earth, and even from here, about fifty million kilometers at 

the closest, with a telescope we can see a lot things about Mars. It has clear dark and light 

features; you can see it has a polar cap. Like the Earth, Mars has an axis that's tilted, and 

therefore it has seasons, winter and summer, and the polar caps grow in the winter and shrink in 

the summer. It also has clouds, so you can tell that it has an atmosphere. 

But to really get a good look at Mars, you need a spacecraft. You need to get up close, 

and now we can see really interesting things about Mars. The first thing that spacecraft learned 

when they visited Mars in 1964 was that it has a lot of craters. It's a lot like the Moon. It's been 

heavily bombarded, which is reasonable because it's closer to the asteroid belt than we are, so 

you do get asteroids that hit the planet Mars. From these first spacecraft to visit Mars we also 

learned that its atmosphere is very thin-- less than 1% as thick as Earth’s atmosphere. 

After the first spacecraft, which just flew past the planet, we put spacecraft into orbit. 

Viking looked at it more carefully and saw that Mars has what appears to be dry river beds. 

These look like dry rivers. So Mars once had water. Today, Mars is a very cold and dry world, 

so what happened to the water? Where is it now? As we know, water is very important. It's 

important for life - all of us drink it. We also know that as soon as the planet Earth has a surface 

cool enough that water could condense on it, life formed on Earth. That was a few billion years 

ago. But once, perhaps several billion years ago, Mars also had water. So it seems very probable 

that it might once have had life. We do have a pretty good guess that underneath the soil on 

Mars, there is still water in the form of permafrost.-- the Mars Odyssey mission will tell us about 

this. 

Mars is the planet of extremes. It has the largest canyon the solar system, the Valles 

Marineris, a canyon that extends almost a third of the way across Mars. They named it Valles 
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Marineris, the "Canyon of the Mariner", because it was discovered by the Mariner spacecraft. 

This is a canyon four thousand kilometers long, and in places nearly ten kilometers deep. (In my 

novel, my characters spend much of their time exploring and climbing through Valles 

Marineris.) 

Mars has the largest mountains in the solar system as well. Olympus Mons, the largest, 

rises up twenty-five kilometers. It's a volcano so tall that the top of it is in vacuum and outside 

the atmosphere. It is far taller than Mount Everest. 

The Pathfinder Mission and Landing on Mars

Pathfinder was a solar-powered spacecraft. Before Pathfinder nobody had used solar 

power on Mars before; Pathfinder was a first. Analyzing the operation of solar power systems 

on Mars was a project that I worked on, and I am very proud that some of my work helped in the 

design of the power system for this spacecraft. 

Pathfinder came down in a parachute, and then the airbags inflated. It bounced on the 

surface, as high as a five story building, and at least eighteen times. That was just as many as 

they counted; it probably bounced more than that. Then it opened up, like a flower unfolds, and 

the blue solar petals on the inside were revealed, and we got to see the Sojourner rover. 

Six Wheels on Soil!

The Sojourner rover really was the real star of the show. This is the first time that 

anybody has operated a wheeled vehicle on another planet, and I'm pleased to tell you that it set a 

world speed record for the fastest vehicle ever to go on the world of Mars. The speed record was 

a little bit under half a meter per minute--that's about one-fiftieth of a mile per hour--but that is 

faster than anybody has ever gone on Mars before. It has six wheels that enable it to run over 

different kinds of terrain, and walk over rocks. The suspension is articulated to allow it to crawl 

over very large rocks. If a car had the same sort of wheel systems, it could drive over something 
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a rock a meter and a half tall, as tall as a dining room table. So it gives it a good amount of 

ability to go over very rough terrain. 

To pick a name for the Pathfinder rover, they held a contest for schoolchildren. The 

name was chosen by Valerie Ambroise, a school girl from Connecticut. "Sojourner" means 

"wanderer," and the Sojourner rover wanders around on Mars, so it's a very appropriate name. 

The Sojourner rover is stowed on one of the petals covered with solar panels. To drive off the 

petal and onto the surface, they have to deploy rolled-up ramps. These ramps to get the rover to 

the surface are spring-loaded, so they deploy with an enthusiastic bing. 

The Sojourner rover and the rock "Yogi," viewed by the Pathfinder lander. 

(This image is a mosaic of several dozen individual frames taken by the 

Pathfinder "IMP" camera; close inspection reveals many seams where 

individual frames do not perfectly overlap.) 

Most of the scientists on the mission were geologists, and geologists love to talk about 

rocks. They decided to name all the rocks that they can see, so that when they talk about rocks, 

they remember which one is which. So the first thing they did when they got the pictures down 

was to make a mural of the surface of Mars as seen by the lander camera. They stuck the mural 

on the wall of the conference room and said anybody could name a rock. So if you have a name 

for a rock, you just write it on a little yellow piece of paper, and stick it on to the picture. If 

everybody likes it, they'll leave it up, and if they don't like it, some body else will name the rock. 

I'm very proud of one rock, "Yogi," which I named, and which was featured very prominently in 

the news coverage! Pathfinder mission had other instruments on it as well, including the APXS 
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("Alpha Proton X-ray Spectrometer") that could actually sniff the rocks and find out what they 

are made out of. It was a very capable instrument. 

The Pathfinder lander, surrounded by deflated airbags, as viewed by the 

Sojourner rover's camera. 

Future Missions to Mars

Pathfinder is not the end of Mars exploration. We have a whole armada of spacecraft 

going to the red planet. The Mars Global Surveyor is in orbit around Mars right now and has a 

mapping camera that shows very detailed close-up pictures of the surface of Mars from orbit. 

I worked on another mission, which was intended to launch in 2001, called the 2001 

Surveyor lander. Unfortunately in 1999 two missions to Mars both failed, and because of those 

failures, the 2001 lander mission was postponed and then cancelled. We were all very 

disappointed. Another mission did launch to Mars in 2001, an orbiter, the Mars “Odyssey” 

mission. The Odyssey spacecraft is in orbit around Mars right now, and taking measurements of 

Mars from orbit. 

Many future missions are now being planned. The next mission to land on Mars is the 

Mars Exploration Rovers, two rovers each one much larger than the Sojourner rover, to launch in 

the summer of next year. 2003. At the same time, the British are heading to Mars with a small 

lander named the Beagle-2, a spacecraft which "hitchhike" to Mars with the ESA "Mars Express" 

orbiter. And then in 1005, the "Mars Reconaissance Orbiter" is going to fly. 

Further in the future, in 2007 we will fly the Mars "Scout" missions. This is a solicitation 

for new concepts in Mars exploration, and several new ideas have been proposed. Some people 

that I work with would like to fly an airplane in the atmosphere of Mars. This is very difficult, 

because the atmosphere is so thin. Some people have suggested flying a balloon, and other 

people have suggested landing a spacecraft on the ice of the polar cap, and melting down through 
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the ice to see the layers under the ice. Another group is proposing a long-range rover to drive 

across the fascinating layered terrain around the polar cap. 

The Mars Exploration Rover. Two of these rovers will launch to Mars in 

the summer of 2003. 

Rock drilling tool on the 2003 Mars Exploration Rover 

We would like to actually get samples back to Earth in a future mission, probably in the 

year 2015, which is only thirteen years from now, and blast them all home so we can take a look 

at them and look for fossils and for other interesting things. 

All of these robotic flights are precursors to the most important future exploration: a 

mission to Mars with people on board. But right now there is no mission planned, so this is more 

science fiction than science. 
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In my science fiction novel, Mars Crossing, I picture such an expedition to Marsin fact, 

several expeditions. The difficult part of sending people to Mars is not how to send them to 

Marsthe difficult part is bringing them home. (And most of my novel is about how the 

characters work at coming home). In the novel, the expeditions to Mars manufacture rocket fuel 

from resources found on Mars to bring the expedition home. One of the expeditions lands on the 

polar cap, and makes rocket fuel out of the carbon dioxide and water ice in the cap, and the other 

expeditions lands near the equator, and manufactures fuel out of the atmospheric carbon dioxide. 

I think that this is very realistic, and that when we do send humans to Mars, that this is the 

logical way to do itwe should make the rocket fuel on Mars, instead of bringing it from Earth. 

Of course, in my story, the characters have tremendous difficulties, and are in great danger. I 

hope that in the real world, they will not have so many problems! The best expedition is one that 

is not very exciting. But perhaps this is one of the functions of science fiction, to show what the 

problems might be. 

I do think that eventually people will go to Mars. It is our sister planet, and we should go 

explore it! 

References

1. "The Rover Team" (J. Matijevic, D. Bickler, D. Braun, H. Eisen, L. Matthies, A. Mishkin, H. 

Stone, L. Sword, L. van Niewstadt, L-C. Wen, B. Wilcox, D. Ferguson, G. Landis, L. Oberle 

et al.) "Characterization of the Martian Surface Deposits by the Mars Pathfinder Rover, 

Sojourner," Science, Vol. 278, 1765–1768, Dec. 5 1997. 

2. "The Rover Team" (J. Matijevic, D. Bickler, D. Braun, H. Eisen, L. Matthies, A. Mishkin, H. Stone, 

L. Sword, L. van Niewstadt, L-C. Wen, B. Wilcox, D. Ferguson, G. Landis, L. Oberle et al.) "The 

Pathfinder Microrover," J. Geophysical Research, Vol. 102, No. E2, 3989–4001 (1997). 

3. G. Landis, "Water, Pink Salt and Cold Dry Gullies: Halobacteria and the Case for Life on 

Mars," Analog, April 2001. 

4. G. Landis, "Adventures in the Mars Business," Analog, July 1998. 

5. P. Jenkins and G. Landis, "A Rotating Arm Using Shape-memory Alloy," presented at Space 

Mechanisms Conference, NASA Johnson Space Center, Houston, TX, 17–19 May 1995. 

6. P. Jenkins, G. Landis, and L. Oberle, "Materials Adherence Experiment: Technology," paper 

IECEC–97339, Proceedings of the 32nd Intersociety Energy Conversion Engineering 

Conference, Vol. 1, 728–731, July 27–Aug. 1 1997, Honolulu HI. 

Robots in the Planetary Cold

Dr. William (Red) Whittaker, director of the Field Robotics Center of the Robotics 

Institute at Carnegie Mellon University, discussed operation of robotic explorers in challenging 

environments, including the Moon and Mercury. He gave historical background from the 

Russian Lunokhod tele-operated rover, the American Apollo manned rover vehicle and terrestrial 

robots including Nomad, which found meteorites in Antarctic and Pioneer, the robot that 

explored the damaged Chernobyl nuclear plant in Russia. 

The main emphasis of the presentation was on autonomously controlled, sunsynchronous robots that are continuously operated by solar power. These are practical on slowly 

rotating bodies such as the Moon (28 days rotation) and Mercury (187 days) or on bodies with a 

tilted axis that allow continuous sunshine at polar regions during summer, such as Earth and 

Mars. Issues impacting sun synchrony are shown in the charts reproduced below. 
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Candidate Coatings and Dry Traction Drives for Planetary Vehicles 

Robert Fusaro and Fred Oswald of the Mechanical Components Branch discussed 

“Candidate Coatings and Dry Traction Drives for Planetary Vehicles”. Vehicles to be designed 

for exploration of planets and moons of the solar system will require reliable mechanical drives 

to operate efficiently. Long-term operation of these drives will be challenging because of 

extreme operating conditions. These extreme conditions include: very high and/or very cold 

temperatures, wide temperature ranges, dust, vacuum or low-pressure atmospheres, and corrosive 

environments. 

Most drives used on Earth involve oil-lubricated gears. However, due to the extreme 

conditions on planetary surfaces, it may not be advisable or even possible to use oil lubrication. 

Unfortunately, solid lubricants do not work well when applied to gears because of the high 

contact stress conditions and large sliding motion between the teeth, which cause wear and limit 

life. We believe traction drives will provide an attractive alternative to gear drives. Traction 

drives are composed of rollers that provide geometry more conducive to solid lubrication. 

Minimal slip occurs in this contact geometry and thus there is very low wear to the solid 

lubricant. 

The challenge for these solid-lubricated drives is finding materials or coatings that 

provide the required long-life while also providing high traction. We seek materials that provide 

low wear with high friction. 
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A coating that has structural strength but still has the ability to flow at the interface can support the load 

and the wear process is one of gradual wear through the coating (left). Coatings without sufficient 

structural strength can still lubricate by forming a very thin film at the metallic surface. The life of this 

lubrication mechanism is strongly dependent on the topography of the metallic surface.

Photomicrograph showing the thin film lubricating mechanism for a polyimide coating that was unable to 

support the load. A thin film of material at the metallic surface has formed and the roughness (scratches) 

in the surface helps hold the material in place to provide a long endurance life. Most soft lamellar solid 

lubricants lubricate by this mechanism. Proper substrate surface preparation is important for obtaining a 

long endurance life. 
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This table shows the friction and wear of various sliding couples illustrating that low friction and low wear 

do not always occur at the same time. For traction drives we want high friction and low wear. One should 

not assume that just because you have high friction you will also have high wear. 

This table shows the friction and wear of some commercially available composite materials sliding against 

various counterface materials in dry air. The table illustrates how the counterface can markedly affect the 

tribological properties of a composite. Thus it may be possible to develop better traction drive rollers by 

considering materials that have higher friction when sliding against low wear composites or coatings. 
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This table compares the friction and wear properties in air and vacuum to illustrate how oxygen and water 

vapor can affect tribological properties. The results show that the PMDA polyimide or the Graphite Fiber 

Reinforce Polyimide (GFRPI) have potential for traction drive rollers in a planetary environment. 

Plasma Sprayed (PS) coatings were developed for high temperature lubrication applications. This figure 

illustrates that in oscillating journal bearing tests the friction remains relatively high over a range of 

temperatures from -107o to +870o C. This high friction characteristic makes these materials candidates for 

traction drives for space applications on cold planetary surfaces.
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The loss in radial clearance (wear) for the oscillating journal bearing tests indicates that wear is relatively 

low at -107oC when compared to room temperature (25oC) indicating that for cold planetary surfaces this 

could be a good traction drive material. 
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Left, Mars Athena '03 rover. Right, Boeing concept for a pressurized Lunar rover.
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For a traction drive, we need high friction (traction) with low wear. 

The 100% PMDA polyimide solid (#5) and film (#8) materials show promise. 

This simple device can test traction roller materials in vacuum. It includes provision to cool the rollers 

through hollow shafts. With minor modification, it can also test gears. 
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Partly completed traction drive tester is at left. Project awaits restored funding. 
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Fresh Ideas for Lubricants, Thinking Out of the Box 

Lois Gschwender of the U.S. Air Force Research Laboratory, Materials Directorate, at 

Wright-Patterson Air Force Base discussed new and novel lubricants including 

Perfluoropolyalkylether (PFPAE), Multiply Alkylated Cyclopentane (MAC), Silahydrocarbon 

(SiHC) and some solid coatings. 

Synthetic lubricants are replacing mineral oils because of their lower volatility and better 

low temperature performance. PFPAE fluids are the best liquids regarding viscosity temperature 

properties (can be used to –54 oC and lower) and low volatility, but can only be used a low loads 

and may cause tribocorrosion. MAC fluids have many attractive properties, but are limited to –

40 o

C. SiHCs have excellent low volatility and can be used to –54 oC. Some extended bearing 

tests with these lubricants have been successfully conducted at ITT and Lockheed, but long-term 

results are pending. 

A filtered-arc TiCN coating process has had very promising results in bench tests at 

Wright-Patterson and UES, Inc. under Air Force contracts. See the presentation charts for more 

details on these new lubricant materials. 
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Pennzane is being used more and more in spacecraft and has many advantages over mineral oils or 

perfluoropolyalkylether oils. 
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Viscosity index is an indication of the fluid's liquid temperature range. 

The higher the number the larger the temperature range. 

Shows a super critical fluid chromatogram of a silahydrocarbon fluid. 

It is essentially unimolecular. 
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Shows T1/2, as described above, of several space lubricants. 
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Shows a twin disk traction (torque) profile for three space lubricants. 
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Shows viscosity temperature properties for silahydrocarbon and Pennzane lubricants. 

Shows wear rates for different space lubricants in vacuum 4-ball testers. 
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Shows results of Spin Orbit Tribometer tester at NASA Glenn for various space lubricants. 
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Torque readout of tester explained above showing smooth running of silahydrocarbon oil. 
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Torque readout of tester explained above showing smooth running of silahydrocarbon oil. 

Favorable results from hard coatings on steel surfaces. 
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Using Condensed Gasses and Novel Liquids for Lubrication on the 

Martian Surface 

Wilfredo Morales of the NASA Glenn Mechanical Components Branch discussed using 

condensed gasses as lubricants or working fluids for Martian exploration. 

The future use of various land vehicles on the Martian surface is inevitable. These 

vehicles must be designed to function under the extreme conditions of the Martian climate. One 

critical design challenge is the lubrication system. 

Lubricating oils, as we use them on Earth, will be useless on Mars unless extensive 

heating systems are employed to ensure flow. But the thought occurs, many common substances 

that are gases on Earth will be liquids on Mars. In particular, carbon dioxide will be a liquid in 

the cold Martian temperature with a moderate increase in pressure. This property of carbon 

dioxide along with its ability to dissolve a number of substances may allow the design of simple, 

reliable lubricating systems. 
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Passive Magnetic Bearing Development 

Mark Siebert, NASA Glenn Mechanical Components Branch discussed magnetic 

bearings for use on flywheel energy storage systems that are being considered as efficient energy 

storage devices for use on unmanned, low earth orbit satellites. These systems are expected to 

provide five to ten times improvement in specific energy storage capacity with longer life than 

current battery systems. 

Low-loss magnetic bearings will be needed to support the flywheel rotor. For smaller 

satellites, we are investigating a simple system that uses only passive magnets for radial bearing 

support and jewel bearings for axial support. 

This presentation describes a study on a 100 percent passive magnetic bearing flywheel 

rig with no active control components. The objective was to determine whether the bearing 

system has sufficient stiffness and damping built in to allow performance over the required speed 

range. 
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`
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The rotor is suspended radially by two pairs of axially magnetized permanent magnets 

and axially by disk-shaped magnets in a ferrofluid-filled cavity. 

The rotor is suspended radially by two pairs of axially magnetized permanent magnets 

and axially by jewel bearings on both ends of the rotor. 
NASA/CP2002-211882 59 

 This rig is the result of improvements in the two designs shown above.
NASA/CP2002-211882 60 
NASA/CP2002-211882 61 

The magnets are stacked with like poles adjacent to each other. 
NASA/CP2002-211882 62 

The ball of the jewel bearing is a 3.175 mm (0.125 inch) silicon nitride ball. 

The disk of the jewel bearing is 440C stainless steel. 
NASA/CP2002-211882 63 

Schematic of finite elements model used to analytically predict stiffness of magnetic bearing. 
NASA/CP2002-211882 64 

Experimental measurement of magnetic bearing radial stiffness. 
NASA/CP2002-211882 65 
NASA/CP2002-211882 66 

Experimental measurement of magnetic bearing axial stiffness. 
NASA/CP2002-211882 67 
NASA/CP2002-211882 68 
NASA/CP2002-211882 69 
NASA/CP2002-211882 70 

Eddy Current Damper for Cryogenic Applications 

Scott Starin and Fred Crosno of CDA Intercorp discussed the advantages of the use of 

eddy current dampers. Eddy current dampers offer reliable, repeatable damping characteristics 

over a wide temperature range. The test results proved the low static friction eddy current 

dampers may be used as a direct replacement for fluid dampers (form, fit, and function) with 

much higher reliability. 
NASA/CP2002-211882 71 
NASA/CP2002-211882 72 
NASA/CP2002-211882 73 
NASA/CP2002-211882 74 
NASA/CP2002-211882 75 
NASA/CP2002-211882 76 
NASA/CP2002-211882 77 
This publication is available from the NASA Center for AeroSpace Information, 301–621–0390.

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Conference Publication

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National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135–3191

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National Aeronautics and Space Administration

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Available electronically at http://gltrs.grc.nasa.gov

September 2002

NASA CP—2002-211882

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Space mechanisms; Actuators; Robots; Planetary exploration; Traction drives; Lubrication

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Proceedings of a conference held at and sponsored by NASA Glenn Research Center, Cleveland, Ohio, May 14, 2002.

Responsible person, Fred B. Oswald, organization code 5950, 216–433–3957.

Space Mechanisms Technology Workshop

Fred B. Oswald, editor

The Mechanical Components Branch at NASA Glenn Research Center hosted a workshop on Tuesday, May 14, 2002, to

discuss space mechanisms technology. The theme for this workshop was “Working in the Cold,” a focus on space mechanisms that must operate at low temperatures. We define “cold” as below –60 °C (210 K), such as would be found near the

equator of Mars. However, we are also concerned with much colder temperatures such as in permanently dark craters of

the Moon (about 40 K).