Technology Focus

Electronics/Computers

Software

Materials

Mechanics

Machinery/Automation

Manufacturing & Prototyping

Bio-Medical

Physical Sciences

Information Sciences

Books and Reports

06-06 June 2006

NASA Tech Briefs, June 2006 1

INTRODUCTION

Tech Briefs are short announcements of innovations originating from research and development activities of the National Aeronautics and Space Administration. They emphasize

information considered likely to be transferable across industrial, regional, or disciplinary lines

and are issued to encourage commercial application.

Availability of NASA Tech Briefs and TSPs

Requests for individual Tech Briefs or for Technical Support Packages (TSPs) announced herein should

be addressed to

National Technology Transfer Center

Telephone No. (800) 678-6882 or via World Wide Web at www2.nttc.edu/leads/

Please reference the control numbers appearing at the end of each Tech Brief. Information on NASA’s 

Innovative Partnerships Program (IPP), its documents, and services is also available at the same facility or

on the World Wide Web at http://ipp.nasa.gov. 

Innovative Partnerships Offices are located at NASA field centers to provide technology-transfer access to

industrial users. Inquiries can be made by contacting NASA field centers and Mission Directorates listed below.

Ames Research Center

Lisa L. Lockyer

(650) 604-1754

lisa.l.lockyer@nasa.gov

Dryden Flight Research Center

Gregory Poteat

(661) 276-3872

greg.poteat@dfrc.nasa.gov

Goddard Space Flight Center

Nona Cheeks

(301) 286-5810

Nona.K.Cheeks.1@nasa.gov

Jet Propulsion Laboratory

Ken Wolfenbarger

(818) 354-3821

james.k.wolfenbarger@jpl.nasa.gov

Johnson Space Center

Helen Lane

(713) 483-7165

helen.w.lane@nasa.gov

Kennedy Space Center

Jim Aliberti

(321) 867-6224

Jim.Aliberti-1@nasa.gov

Langley Research Center

Robert Yang

(757) 864-8020

robert.l.yang@nasa.gov

John H. Glenn Research Center at

Lewis Field

Robert Lawrence

(216) 433-2921

robert.f.lawrence@nasa.gov

Marshall Space Flight Center

Vernotto McMillan

(256) 544-2615

vernotto.mcmillan@msfc.nasa.gov

Stennis Space Center

John Bailey

(228) 688-1660 

john.w.bailey@nasa.gov

Carl Ray

Small Business Innovation 

Research Program (SBIR) &

Small Business Technology

Transfer Program (STTR)

(202) 358-4652

carl.g.ray@nasa.gov

Merle Mckenzie

Innovative Partnerships Program

(Code TD)

(202) 358-2560

merle.mckenzie@hq.nasa.gov

John Mankins

Exploration Systems Research

and Technology Division

(202) 358-4659

john.c.mankins@nasa.gov

Terry Hertz

Aeronautics and Space Mission

Directorate

(202) 358-4636

thertz@mail.hq.nasa.gov

Glen Mucklow

Mission and Systems 

Management Division (SMD)

(202) 358-2235

gmucklow@

mail.hq.nasa.gov

Granville Paules

Mission and Systems 

Management Division (SMD)

(202) 358-0706

gpaules@mtpe.hq.nasa.gov

Gene Trinh

Human Systems Research and

Technology Division (ESMD)

(202) 358-1490

eugene.h.trinh@nasa.gov

John Rush

Space Communications Office

(SOMD)

(202) 358-4819

john.j.rush@nasa.gov

NASA Field Centers and Program Offices

NASA Mission Directorates

At NASA Headquarters there are four Mission Directorates under

which there are seven major program offices that develop and

oversee technology projects of potential interest to industry:

5 Technology Focus: 

Test & Measurement

5 Magnetic-Field-Response 

Measurement-Acquisition System

6 Platform for Testing Robotic Vehicles on

Simulated Terrain

7 Interferometer for Low-Uncertainty Vector

Metrology

8 Rayleigh Scattering for Measuring Flow in a

Nozzle Testing Facility

11 Electronics/Computers

11 “Virtual Feel” Capaciflectors

12 FETs Based on Doped Polyaniline/Polyethylene

Oxide Fibers 

13 Miniature Housings for Electronics With 

Standard Interfaces

15 Software

15 Integrated Modeling Environment

15 Modified Recursive Hierarchical 

Segmentation of Data

15 Sizing Structures and Predicting Weight of a

Spacecraft

15 Stress Testing of Data-Communication Networks

16 Framework for Flexible Security in Group

Communications

16 Software for Collaborative Use of Large

Interactive Displays

17 Materials

17 Microsphere Insulation Panels

17 Single-Wall Carbon Nanotube Anodes for 

Lithium Cells 

18 Tantalum-Based Ceramics for Refractory

Composites

21 Mechanics

21 Integral Flexure Mounts for Metal Mirrors for

Cryogenic Use

23 Manufacturing & Prototyping

23 Templates for Fabricating Nanowire/NanoconduitBased Devices

24 Measuring Vapors To Monitor the State of Cure

of a Resin

25 Physical Sciences

25 Partial-Vacuum-Gasketed Electrochemical

Corrosion Cell

25 Theodolite Ring Lights

27 Information Sciences

27 Integrating Terrain Maps Into a Reactive

Navigation Strategy

27 Reducing Centroid Error Through Model-Based

Noise Reduction

28 Adaptive Modeling Language and Its Derivatives

29 Books & Reports

29 Stable Satellite Orbits for Global Coverage 

of the Moon

29 Low-Cost Propellant Launch From a 

Tethered Balloon

06-06 June 2006

NASA Tech Briefs, June 2006 3

This document was prepared under the sponsorship of the National Aeronautics and Space Administration. Neither the United States Government nor any person acting on behalf of the United States Government assumes any liability resulting from the use of the information contained

in this document, or warrants that such use will be free from privately owned rights.

NASA Tech Briefs, June 2006 5

Magnetic-Field-Response Measurement-Acquisition System

Sensors are interrogated without physical connection to a power source, microprocessor, dataacquisition equipment, or electrical circuitry.

Langley Research Center, Hampton, Virginia

A measurement-acquisition system

uses magnetic fields to power sensors

and to acquire measurements from sensors. The system alleviates many shortcomings of traditional measurement-acquisition systems, which include 

a finite number of measurement channels, weight penalty associated with

wires, use limited to a single type of

measurement, wire degradation due to

wear or chemical decay, and the logistics

needed to add new sensors. Eliminating

wiring for acquiring measurements can

alleviate potential hazards associated

with wires, such as damaged wires becoming ignition sources due to 

arcing.

The sensors are designed as electrically passive inductive-capacitive or 

passive inductive-capacitive-resistive circuits that produce magnetic-field re--

sponses. One or more electrical parameters (inductance, capacitance, and

resistance) of each sensor can be variable and corresponds to a measured

physical state of interest. The magneticfield-response attributes (frequency, amplitude, and bandwidth) of the inductor

correspond to the states of physical

properties for which each sensor measures.

For each sensor, the measurement-acquisition system produces a series of increasing magnetic-field harmonics

within a frequency range dedicated to

that sensor. For each harmonic, an antenna electrically coupled to an oscillating current (the frequency of which is

that of the harmonic) produces an oscillating magnetic field. Faraday induction via the harmonic magnetic fields

produces an electromotive force and

therefore a current in the sensor. Once

electrically active, the sensor produces

its own harmonic magnetic field as the

inductor stores and releases magnetic

energy. The antenna of the measurement-acquisition system is switched

from a transmitting to a receiving mode

to acquire the magnetic-field response

of the sensor. The rectified amplitude

of the received response is compared to

previous responses to prior transmitted

harmonics, to ascertain if the measurement system has detected a response inflection. The “transmit-receive-compare” of sequential harmonics is

repeated until the inflection is identified. The harmonic producing the amplitude inflection is the sensor resonant

frequency. Resonant frequency and response amplitude are stored and then

correlated to calibration data. 

Multiple sensors can be interrogated

using a single acquisition system. Each

sensor must have a dedicated frequency

partition of the antenna bandwidth,

and the interrogation system must be

augmented with a measurement correlation table for each sensor. The

method eliminates the need for a data

acquisition channel dedicated to each

sensor. Any existing inductive or capacitive sensor can also be modified to be

interrogated using this method.

The use of magnetic fields for powering sensors and for acquiring the measurements from them eliminates the

need for physical connection from the

sensors to a power source and data-acquisition equipment. Because magnetic

fields are used to power the sensors

that, in turn, respond with their own

magnetic fields, the attributes of which

are dependent upon the physical properties being measured, this class of sensors is referred to as magnetic-field-response sensors.

Because the functionality of the magnetic-field-response sensors is based

upon magnetic fields, the sensors can

be used under such conditions as in

caustic environments, acids, high temperatures, cryogenic temperatures,

high pressures, and radiative environments. Furthermore, the method allows

acquiring measurements that were previously unattainable or logistically difficult because there was no practical

means of getting power and data-acquisition electrical connections to a sensor.

A novel feature of the method is that an

individual sensor can be used to measure simultaneously more than one

physical state. This is achieved by correlating combinations of different physical states to combinations of different

sensor response attributes. Another

novel feature of the method is that a

sensor can be used to measure a permanent transition of one physical state to

another. Once the new physical state

has been achieved (e.g., material phase

transition), the sensor can simultaneously measure other physical states.

The magnetic-field-response recorder

shown in Figure 1 is a handheld version

of the measurement-acquisition system

using the method discussed. Figure 2

shows a fluid-level sensor being interrogated using the recorder internal antenna and an external antenna. The

programmable recorder is designed to

be simple to use and is capable of powering and acquiring measurements

from any magnetic-field-response sensor. It can acquire and interpret measurements that correspond to either the

amplitude, frequency, and/or bandwidth of the magnetic-field-response

sensor. Resonant response frequency

Figure 1. A Portable Magnetic-Field-Response

Recorder is shown in a handheld version.

LAR16908 ABPI 1-25-06 CC

Technology Focus: Test & Measurement
6 NASA Tech Briefs, June 2006

and amplitude of each sensor are displayed. The amplitude is dependent

upon distance at which the sensor is interrogated. The recorder can be programmed to display the physical value

of the measurement. The magneticfield-response recorder has an internal

antenna, connector for external antenna, and an analog output.

The measurement-acquisition method

has many advantages over other methods

currently in use. Once electrically excited, the sensors have very low voltage. If

a short does occur in the sensor, the sensor will not be electrically active because

a completed circuit is needed for Faraday induction. Hence, electrical arcing is

prevented. Because the measurement

system and sensors do not necessitate a

physical connection to a power source or

data-acquisition equipment, they are

easy to implement into existing vehicles,

structures, or other existing systems. The

measurement system can be installed

during any phase of vehicle life, and it is

less costly to install new sensors than the

traditional method of wiring a sensor to

acquisition equipment. Such a system

can be used to implement measurements

that were not envisioned during design

of a vehicle or structure but identified as

needed during testing or operation. New

measurements only require that the new

sensors be placed within the magnetic

field of the interrogating antenna(s). No

wiring is required. Many of the sensors

and interrogating antennas can be made

lightweight and non-obtrusive by directly

placing on the vehicle or structural components using metallic-film deposition

methods.

This work was done by Stanley E. Woodard,

Qamar A. Shams, and Robert L. Fox of Langley Research Center and Virginia and

Bryant D. Taylor of Swales Aerospace Corporation. Further information is contained in a

TSP (see page 1).

LAR-16908

Figure 2. Interrogation of a Wireless Fluid-Level Sensor is shown using the magnetic-field-response recorder.

LAR16908 Fig 2 ABPI

1-25-06 CC

FLUID-LEVEL SENSOR BEING INTERROGATED

USING EXTERNAL ANTENNA

FLUID-LEVEL SENSOR BEING INTERROGATED

USING INTERNAL ANTENNA

Antenna

Sensor

Magnetic-FieldResponse Recorder

The variable terrain tilt platform

(VTTP) is a means of providing simulated terrain for mobility testing of engineering models of the Mars Exploration Rovers. The VTTP could also be

used for testing the ability of other robotic land vehicles (and small vehicles

in general) to move across terrain

under diverse conditions of slope and

surface texture, and in the presence of

obstacles of various sizes and shapes.

The VTTP consists mostly of a 16-ft-

(4.88-m)-square tilt table. The tilt can

be adjusted to any angle between 0°

(horizontal) and 25°. The test surface of

the table can be left bare; can be covered with hard, high-friction material;

or can be covered with sand, gravel,

and/or other ground-simulating material or combination of materials to a

thickness of as much as 6 in. (≈15 cm).

Platform for Testing Robotic Vehicles on Simulated Terrain

Slope, ground material, and obstacles can be varied. 

NASA’s Jet Propulsion Laboratory, Pasadena, California
Models of rocks, trenches, and other obstacles can be placed on the simulated

terrain.

For example, for one of the MarsRover tests, a high-friction mat was attached to the platform, then a 6-in.-

(≈15 cm) deep layer of dry, loose beach

sand was deposited on the mat. The

choice of these two driving surface materials was meant to bound the range of

variability of terrain that the rover was

expected to encounter on the Martian

surface. At each of the different angles

at which tests were performed, for some

of the tests, rocklike concrete obstacles

ranging in height from 10 to 25 cm

were placed in the path of the rover

(see figure).

The development of the VTTP was accompanied by development of a

methodology of testing to characterize

the performance and modes of failure

of a vehicle under test. In addition to

variations in slope, ground material, and

obstacles, testing typically includes driving up-slope, down-slope, cross-slope,

and at intermediate angles relative to

slope. Testing includes recording of

drive-motor currents, wheel speeds, articulation of suspension mechanisms,

and the actual path of the vehicle over

the simulated terrain. The collected

data can be used to compute curves that

summarize torque, speed, power-demand, and slip characteristics of wheels

during the traverse.

This work was done by Randel Lindemann

of Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in

a TSP (see page 1).

NPO-42522

NASA Tech Briefs, June 2006 7

A Model Robotic Vehicle was driven over 25-cm obstacles on simulated terrain at a tilt of 20°.

NPO-42522

ABPI

3-27-06 ca

The figure is a simplified schematic diagram of a tilt-sensing unequal-path interferometer set up to measure the orientation of the normal vector of one

surface of a cube mounted on a structure under test. This interferometer has

been named a “theoferometer” to express both its interferometric nature

and the intention to use it instead of an

autocollimating theodolite.

The theoferometer optics are

mounted on a plate, which is in turn

mounted on orthogonal air bearings for

near-360° rotation in azimuth and elevation. Rough alignment of the theoferometer to the test cube is done by hand,

with fine position adjustment provided

by a tangent arm drive using linear inchwormlike motors.

In the operation of the theoferometer, the interference pattern formed by

the collimated laser beams reflected

from the two cubes is focused onto a

In this Interferometer, the interference pattern formed by the laser beams from the cubes is imaged

onto the CCD. This pattern would depend on the angular misalignment between the cubes and would

be analyzed to determine the misalignment.

Beam

Splitter

Reference

Cube

Spatial

Filter

Optics

Laser CCD

Fold

Flat

Test

Cube

Structure Under Test

Interferometer Plate

(Mounted on Azimuth and

Elevation Rotation Stage)

GSC-14753-1 ABPI 12-14-04 es

Interferometer for Low-Uncertainty Vector Metrology

Accuracy is increased; time and cost are reduced.

Goddard Space Flight Center, Greenbelt, Maryland
A molecular Rayleigh-scatteringbased air-density measurement system

was built in a large nozzle-and-enginecomponent test facility for surveying

supersonic plumes from jet-engine exhaust. The facility (see Figure 1) can

test nozzles up to 8.75 in. (22.2-cm) in

diameter. It is enclosed in a 7.5-ft (2.3-

m) diameter tank where ambient pressure is adjusted to simulate engine operation up to an altitude of 48,000 ft

(14,630 m). The measurement technique depends on the light scattering

by gas molecules present in the air; no

artificial seeding is required. Commercially available particle-based techniques, such as laser Doppler velocimetry and particle image

velocimetry, were avoided for such reasons as requirement of extremely large

volume of seed particles; undesirable

coating of every flow passages, model,

and test windows with seed particles;

and measurement errors from seed

particles not following the flow. The

molecular Rayleigh-scattering-based

technique avoids all of these problems;

however, a different set of obstacles associated with cleaning of dust particles, avoidance of stray light, and protection of the optical components

from the facility vibration need to be

addressed. 

To avoid a problem with facility vibration, light from a single-mode continuous-wave laser was transmitted

into the vacuum tank by the use of an

optical fiber. It was then collimated

and passed through the plume.

Rayleigh-scattered light from various

points along the collimated beam was

collected by a set of collection lenses

placed outside the vacuum tank and

measured by a photomultiplier tube

(PMT). Large glass windows on the

tank provided optical access. The collimator for the transmitted beam and

the light-collection optics were placed

on two synchronized traversing units

to enable a survey over a cross-section

of the nozzle plume. Although the

technique is suitable to measure velocity, temperature, and density, in this

8 NASA Tech Briefs, June 2006

Fig. 1. The Optical Arrangement is shown with the enclosing tank retracted downstream.

Retracted

Encloser

Tank

Transmitted

Beam

PMT

Collection

Lens

X-Y Traverse

Fiber Coupler 

Laser

Nozzle

Flow

Dump

LEW-17627-1 Fig1 ABPI

11-1-05 CA

charge-coupled device (CCD) detector.

The resulting digitized interference

fringe pattern is then analyzed by dedicated software to determine the angular

misalignment between the two laser

beams (and, hence, the misalignment

between the cubes) at the sub-arcsecond level. If a null fringe pattern were

achieved, it could be concluded that the

laser beam points anti-parallel to the

surface normal of the test cube. Knowledge of the distance from null (via the

angular misalignment seen in the interference pattern) coupled with readings

from azimuth and elevation encoders

calibrated to the laser-pointing direction then gives the orientation of the

cube surface normal vector in two (angular) dimensions. This is the same information as would be given by a

theodolite aligned to the test cube, albeit with greater accuracy.

This system offers several advantages.

The parts used in the prototype unit

were off-the-shelf and relatively inexpensive. Whereas the uncertainty of a

typical theodolite measurement is 1 to 2

arcseconds, the current theoferometer

prototype has a demonstrated uncertainty of about 0.3 arcsecond. Moreover,

the theoferometer makes it possible to

completely automate the data-taking

process, reducing the time required to

take measurements. The net result is

better metrology at lower cost, relative

to metrology by use of an autocollimating theodolite.

This work was done by Ronald W. Toland

and Douglas B. Leviton of Goddard Space

Flight Center. Further information is contained in a TSP (see page 1). GSC-14753-1

Rayleigh Scattering for Measuring Flow in a Nozzle Testing Facility

The facility can test nozzles up to 8.75-in. (22.2-cm) in diameter.

John H. Glenn Research Center, Cleveland, Ohio
NASA Tech Briefs, June 2006 9

Fig. 2. Density Variation is shown along the centerline of a 5.06-in. (12.9-cm) diameter, nozzle-pressure-ratio 10, supersonic jet from a convergent nozzle.

0 1 2 3 4

0.0

0.2

0.4

0.6

0.8

 1.0

Predicted Variation

Measured

Data

r

x

Cognizant

Nozzle Incident Shock

Survey Line

Mach Disk

Axial Distance From Exit/Nozzle Diameter

Density (kg/m3

)

LEW-17627-1 Fig2 ABPI 11-1-05 ca

first entry only air density was measured by monitoring intensity of the

scattered light. Excellent comparison

between theoretically predicted variation and the measured data along the

centerline of a highly underexpanded

supersonic jet provided validation to

the measurement technique (see Figure 2).

This work was done by Carlos R. Gomez

of Glenn Research Center and Jayanta

Panda of the Ohio Aerospace Institute. Further information is contained in a TSP (see

page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed to:

NASA Glenn Research Center

Innovative Partnerships Office

Attn: Steve Fedor

Mail Stop 4–8

21000 Brookpark Road

Cleveland, Ohio 44135.

Refer to LEW-17627-1.

NASA Tech Briefs, June 2006 11

Electronics/Computers

“Virtual Feel” Capaciflectors

Increases in capacitance with deviations from desired central positions would be exploited.

Goddard Space Flight Center, Greenbelt, Maryland

The term “virtual feel” denotes a type

of capaciflector (an advanced capacitive proximity sensor) and a methodology for designing and using a sensor of

this type to guide a robot in manipulating a tool (e.g., a wrench socket) into

alignment with a mating fastener (e.g.,

a bolt head) or other electrically conductive object. Unlike robotic vision,

capacitive proximity sensing does not

require a clear line of sight to the mating fastener. On the contrary, capacitive

proximity sensing affords the greatest

position-measuring sensitivity in the situation in which it is most needed —

when the tool is so close to the fastener

as to prevent viewing.

Capaciflectors, other capacitive proximity sensors, and related developments

have been described in numerous previous NASA Tech Briefs articles. Of those articles, the one most relevant to the present innovation was “Guiding Robots With

The Help of Capaciflectors” (GSC13614), NASA Tech Briefs, Vol. 21, No. 3

(March 1997), page 44. Like other capacitive proximity sensors, a capaciflector includes at least one sensing electrode, excited with an alternating voltage, that

puts out a signal indicative of the capacitance between that electrode and a proximal object.

As described in the cited previous 

article, a robotic manipulator would be

tipped with a tool instrumented with a capaciflector that would include an array of

sensing electrodes that would be somewhat complex because it would be designed to enable three-dimensional proximity sensing. The outputs of the sensing

electrodes would be converted to DC,

digitized, then fed to a digital processor.

In the processor, the variation of sensed

capacitances with relative position and

orientation of the capaciflector and a

sensed object would be used to generate

data equivalent to a fictitious force field

that could be a source of signals to control the motion of the robotic manipulator in the vicinity of the object. Thus, collisions could be avoided and the

manipulator could be guided into proximity and alignment with the intended

object without making premature contact with the object. The initial approach

would typically involve a raster scan of the

manipulator while capaciflector outputs

were processed to determine positions of

closest approach in scan planes that were

progressively brought closer to the object, without bringing them so close as to

risk collision. This scan would yield data

on the approximate position and orientation of the object relative to the manipulator. Following the scan, the capaciflector outputs would be processed and used

for guidance as the manipulator was

dithered into soft contact with the object.

The “virtual feel” capaciflector methodology also involves digitization and processing of capacitance readings as functions of relative position and orientation

to obtain data equivalent to a fictitious

force field that, in this case, is regarded as

providing a quasi-tactile sense of imminent contact. However, a “virtual feel” capaciflector would be electronically and

mechanically simpler because it would

typically include only two electrodes: a

sensing electrode and a shielding electrode. Moreover, the tool could serve as

the sensing electrode. For example, if the

tool were a wrench socket to be mated

with a bolt head, then the wrench socket

would be the sensing electrode (see figure). The sides of the wrench socket

would be covered with a layer of electrically insulating material that would, in

turn, be covered by a metallic outer shell

that would serve as the shielding electrode. The capaciflector output would inCommon

Robot Interface

Shielding

Electrode

Electrical

Insulation

Wrench Socket

(Also Acts as

Sensing

Electrode)

Electric-Field

Lines

Bolt Head

WRENCH SOCKET CENTERED ON

BOLT HEAD, LOWER CAPACITANCE

WRENCH SOCKET NOT CENTERED ON

BOLT HEAD, HIGHER CAPACITANCE

GSC-14955-1

ABPI 8-10-05 es

A Wrench Socket would double as the sensing electrode of a capaciflector. The capacitance between the

bolt head and the wrench socket would be measured as the socket was dithered, in order to derive information needed to keep the socket centered on and clocked to the bolt head in preparation for mating.
12 NASA Tech Briefs, June 2006

dicate the capacitance between the

wrench socket and the bolt head.

The algorithm processing the digitized capaciflector readings would exploit the fact that for any fixed position

of the wrench socket along the central

axis of the bolt head, the capacitance

would reach a minimum when the axis

of the wrench socket coincided with

the axis of the bolt head and the

wrench socket was clocked (rotated

about its axis) to the angular position

for mating with the bolt head: any lateral (horizontal in the figure) translation or any rotation of the wrench

socket away from the central position

and the mating orientation would

cause an increase in capacitance.

Hence, for a given fixed position along

the center line of the bolt, the information needed to correct any deviation of

the wrench socket from the central position and the mating orientation

could be obtained by taking capacitance measurements during a sequence of controlled dithers of the position and orientation along and about

the various coordinate axes. This is

analogous to the feel a skilled craftsman instinctively uses, except it is noncontact, hence, “virtual feel.”

This work was done by John M. Vranish 

of Goddard Space Flight Center. Further information is contained in a TSP (see

page 1).

GSC-14955-1

A family of experimental highly miniaturized field-effect transistors (FETs) is

based on exploitation of the electrical

properties of nanofibers of polyaniline/polyethylene oxide (PANi/PEO)

doped with camphorsulfonic acid.

These polymer-based FETs have the potential for becoming building blocks of

relatively inexpensive, low-voltage, highspeed logic circuits that could supplant

complementary metal oxide/semiconductor (CMOS) logic circuits.

The development of these polymerbased FETs offers advantages over the

competing development of FETs based

on carbon nanotubes. Whereas it is difficult to control the molecular structures

and, hence, the electrical properties of

carbon nanotubes, it is easy to tailor the

electrical properties of these polymerbased FETs, throughout the range from

insulating through semiconducting to

metallic, through choices of doping levels

and chemical manipulation of polymer

side chains. A further advantage of doped

PANi/PEO nanofibers is that they can be

made to draw very small currents and operate at low voltage levels, and thus are

promising for applications in which there

are requirements to use many FETs to obtain large computational capabilities

while minimizing power demands.

Fabrication of an experimental FET in

this family begins with the preparation

of a substrate as follows: A layer of silicon

dioxide between 50 and 200 nm thick is

deposited on a highly doped (resistivity

≈0.01 Ω.cm) silicon substrate, then gold

electrodes/contact stripes are deposited

on the oxide. Next, one or more fibers

of camphorsulphonic acid-doped PANi/

PEO having diameters of the order of

100 nm are electrospun onto the substrate so as to span the gap between the

gold electrodes (see Figure 1).

Figure 2 depicts measured currentversus-voltage characteristics of the device of Figure 1, showing that saturation

channel currents occur at source-todrain potentials that are surprisingly low,

relative to those of CMOS FETs. The

hole mobility in the depletion regime in

this transistor was found to be 1.4 × 10–4

cm2/(V.s), while the one-dimensional

charge density at zero gate bias was estiFETs Based on Doped Polyaniline/Polyethylene Oxide Fibers 

Advantages include tailorability of electronic properties and low power demands. 

John H. Glenn Research Center, Cleveland, Ohio

Figure 1. Fibers of Doped PANi/PEO are electrospun across the gap between source and drain gold

electrodes on a prepared substrate to form an FET. The inset presents a simplified cross section showing one fiber. The rest of the picture is a scanning electron micrograph, wherein fiber A (12 μm long,

300 nm in diameter) and fiber B (18 μm long, 120 nm in diameter) in contact with the two inner gold

electrodes are parts of an experimental FET.

Fiber

Fiber B Gold Electrodes

Fiber A

Au Au

SiO2

Highly Doped Si (Back Gate)
NASA Tech Briefs, June 2006 13

A family of general-purpose miniature

housings has been designed to contain

diverse sensors, actuators, and drive circuits plus associated digital electronic

readout and control circuits. Each housing fits within an envelope having dimensions of about 2-1

⁄4 by 1-3⁄4 by 1⁄2 in. (about

5.7 by 4.4 by 1.3 cm). Each housing can

be secured to a mating carrier by use of

screws or epoxy; this mounting scheme

helps the housings and their contents to

withstand severe vibrations and ensures

thermal conduction for dissipation of

heat generated during operation of the

contained circuitry. The circuits contained in the housings communicate with

the external world via standard RS-485 interfaces. Multiple units comprising housings and their contents can easily be electrically connected together in a

daisy-chain arrangement, within which

individual units are addressable via the

RS-485 bus. Hence, a single master computer connected to the bus can program,

or read data from, any or all such units.

Examples of such units include small

motor drives, programmable thermostats, data loggers, and programmable

controllers. There are numerous potential uses for these units in medical equipment, automotive electronics, manufacturing equipment, and robots.

This work was done by David E. Howard,

Dennis A. Smith, and Dean C. Alhorn of Marshall Space Flight Center. Further information is contained in a TSP (see page 1).

This invention is owned by NASA, and a

patent application has been filed. For further

information, contact Sammy Nabors, MSFC

Commercialization Assistance Lead, at sammy.

a.nabors@nasa.gov. Refer to MFS-32000-1.

Miniature Housings for Electronics With Standard Interfaces

Marshall Space Flight Center, Alabama

mated to be approximately one hole per

50 two-ring repeat units of polyaniline,

consistent with the rather high channel

conductivity (≈10–3 S/cm). Reducing or

eliminating the PEO content of the

fibers is expected to enhance the properties of future versions of this transistor. 

This work was done by Noulie Theofylaktos, Daryl Robinson, and Félix Miranda of

Glenn Research Center; Nicholas Pinto

of the University of Puerto Rico; Alan Johnson, Jr. and Alan MacDiarmid of the University of Pennsylvania; and Carl Mueller

of Analex Corp. Further information is contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to NASA Glenn Research Center, Innovative

Partnerships Office, Attn: Steve Fedor, Mail

Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-17933-1.

0.0

0.0

–0.5

–1.0

–1.5

–2.0

–2.5

–0.2 –0.4 –0.6

Source-to-Drain Potential, Volts

Source-to-Drain Current, nA

–0.8 –1.0

–20 V

0 V

+10 V

+20 V

+30 V

VG

LEW17933-1 Fig 2 ABPI 7-20-05 bs

Figure 2. These Current-Versus-Voltage Characteristics were obtained from measurements on the FET

of Figure 1. The measurements were made at various values of back gate voltage (VG) representative

of the accumulation and depletion modes. 

NASA Tech Briefs, June 2006 15

Software

Integrated Modeling 

Environment

The Integrated Modeling Environment (IME) is a software system that establishes a centralized Web-based interface for integrating people (who may be

geographically dispersed), processes,

and data involved in a common engineering project. The IME includes software tools for life-cycle management,

configuration management, visualization, and collaboration. It enables organized, efficient communication of engineering analyses and the statuses

thereof. Key functions performed by use

of the IME include creation, further development, and management of modeling analyses over their entire life cycles;

publishing model and analysis information for availability and reuse throughout the user community; and managing

legacy information without regard to

original formats, database organizations,

or computing platforms. The use of the

IME creates an archive of analysis results, plus documentation that identifies

the assumptions and data elements used

for each analysis. This archive is configured to enable reuse of previous analysis

results, and tracing of types and versions

of software used for each step of each

analysis. The IME utilizes a customized

version of a commercial product-lifecycle-management app-lication program

that provides rich capabilities for managing configurations, workflows, data,

and access through a single Web-based

environment.

This program was written by Gary Mosier of

Goddard Space Flight Center, and Paul

Stone and Christopher Holtery of Constellation

Software Engineering Corp. Further information is contained in a TSP (see page 1).

GSC-14827-1

Modified Recursive Hierarchical Segmentation of Data

An algorithm and a computer program that implements the algorithm

that performs recursive hierarchical segmentation (RHSEG) of data have been

developed. While the current implementation is for two-dimensional data

having spatial characteristics (e.g.,

image, spectral, or spectral-image data),

the generalized algorithm also applies to

three-dimensional or higher dimensional data and also to data with no spatial characteristics. The algorithm and

software are modified versions of a prior

RHSEG algorithm and software, the outputs of which often contain processingwindow artifacts including, for example,

spurious segmentation-image regions

along the boundaries of processing-window edges. The modification consists of

the addition of an efficient subroutine

through which pairs of regions are identified that may contain pixels that are actually more similar to other regions in

the pair. Once these pairs of regions are

identified, pixels in one region that are

more similar to pixels in the other region are reassigned to the other region.

The subroutine is computationally efficient because it focuses only on those regions that could potentially contribute

to the processing-window artifacts. In addition, any adverse effect of the subroutine on the computational efficiency of

the algorithm is minimized by executing

the subroutine at a point in the algorithm such that switching of pixels between regions that are subsequently

merged is avoided.

This program was written by James C.

Tilton of Goddard Space Flight Center.

For further information, contact the Goddard Innovative Partnerships Office at

(301) 286-5810. GSC-14681-1

Sizing Structures and 

Predicting Weight of a

Spacecraft

EZDESIT is a computer program for

choosing the sizes of structural components and predicting the weight of a

spacecraft, aircraft, or other vehicle. In

designing a vehicle, EZDESIT is used in

conjunction with a finite-element structural-analysis program: Each structural

component is sized within EZDESIT to

withstand the loads expected to be encountered during operation, then the

weights of all the structural finite elements are added to obtain the structural

weight of the vehicle. The sizing of the

structural components elements also alters the stiffness properties of the finiteelement model. The finite-element

analysis and structural component sizing

are iterated until the weight of the vehicle converges to a prescribed iterative

difference. The results of the sizing can

be reviewed in two ways: 

1. An interactive session of the EZDESIT

program enables review of the results

in a table that shows component

types, component weights, and failure

modes; and

2. The results are read into a finite-element preprocessing-and-postprocessing program and displayed on a

graphical representation of the

model.

This program was written by Jeffrey Cerro

and C. P. Shore of Langley Research Center. Further information is contained in a

TSP (see page 1).

LAR-16878-1

Stress Testing of DataCommunication Networks

NetStress is a computer program that

stress-tests a data-communication network and components thereof. NetStress comprises two components running, respectively, in a transmitting

system and a receiving system connected

to a network under test. The novelty of

the program is that is has the capability

to generate/receive varied network

loading traffic profiles, which prior

known programs were incapable of producing (i.e., various packet sizes and various packet rates all combined to make a

pseudo-random traffic pattern). The

transmitting-system component generates increasingly stressful data traffic for

transmission via the network. The receiving-system component analyzes the resulting traffic arriving in the receiving

system, generating such statistics as the

number of data packets successfully received, the number of dropped packets,

and the number of packets received out

of order. The packet sizes must be configured before the transmitting-system

component is started, but the packet frequencies, numbers of packets in bursts,

and burst times can be configured during execution. Typically, a test begins

with transmission of data at low sustained rates. Then the sustained rates

are increased and burst rates are modified while monitoring to determine

whether the receiving-system component reports any losses. When significant

losses are reported, the user seeks to determine whether a malfunction or defi-
16 NASA Tech Briefs, June 2006

ciency has been found or normal network saturation has been attained. NetStress was written for execution in the

VxWorks real-time operating system, but

could easily be ported to other operating systems. 

This program was written by Kurt Leucht

and Guy Bedette of Kennedy Space 

Center. For further information, contact the

Kennedy Innovative Partnerships Office at

(321) 861-7158.

KSC-12589

Framework for Flexible 

Security in Group 

Communications

The Antigone software system defines

a framework for the flexible definition

and implementation of security policies

in group communication systems.

Antigone does not dictate the available

security policies, but provides high-level

mechanisms for implementing them. A

central element of the Antigone architecture is a suite of such mechanisms

comprising micro-protocols that provide

the basic services needed by secure

groups. Policies are implemented

through the composition and configuration of these mechanisms. Mechanisms

are composed in different ways to address new requirements and environmental constraints. The Antigone framework provides an easy-to-use application

programming interface (API), from

which secure group application programs can be built. Written entirely in

the C++ programming language, the system consists of over 18,000 lines of

source code and has been ported to several versions of Linux, FreeBSD, and

SunOS. Information for accessing recent versions of the source code and related documentation is available at

http://antigone.eecs.umich.edu.

This program was written by Patrick McDaniel and Atul Prakash of the University of

Michigan for Kennedy Space Center.

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Electrical Engineering and

Computer Sciences Department

University of Michigan

3115 EECS

1301 Beal Ave.

Ann Arbor, MI 48109

Refer to KSC-12207, volume and number

of this NASA Tech Briefs issue, and the

page number.

Software for Collaborative

Use of Large Interactive

Displays

The MERBoard Collaborative Workspace, which is currently being deployed

to support the Mars Exploration Rover

(MER) Missions, is the first instantiation

of a new computing architecture designed to support collaborative and

group computing using computing devices situated in NASA mission operations rooms. It is a software system for

generation of large-screen interactive

displays by multiple users. The architecture provides a platform and applications programming interface (API) for

the development of collaborative applications for NASA mission operations.

The standard deployment configuration

provides an integrated whiteboard, Web

browser, remote viewing and control for

collaboration over distance, and personal and group storage spaces that provide ubiquitous access and sharing of

data. Customization for specific domains

is provided through plug-ins. For the

MER mission, plug-ins include a flowcharting tool for strategic rover operations and mission planning, 3D visualization of the Martian terrain, a data

navigator to navigate the mission database, and situational awareness tools.

The MERBoard software is designed to

run on large plasma displays with touchscreen overlays, thus providing an immersive and interactive environment for

teams to view, annotate, and share data.

The MERBoard overcomes the obstacles

to communication, retention, and collaborative modification of information

in diverse forms that can include text,

data (including images) from scientific

instruments, handwritten notes, hand

drawings, and computer graphics. The

MERBoard provides a unifying interface

for the integration of heterogeneous applications, and provides those applications with a consistent model for saving

and retrieving data. All applications may

be viewed and controlled from any location that has a MERBoard. A personal

client provides integration of a user’s

personal computing environment with

the MERBoard environment. 

This program was written by Jay Trimble,

Thodore Shab, Roxana Wales, Alonso Vera,

Irene Tollinger, Michael McCurdy, and

Dmitriy Lyubimov at Ames Research Center. For further information, contact the

Ames Technology Partnerships Division at

(650) 604-2954.

ARC-14951-1
NASA Tech Briefs, June 2006 17

In recent experiments, highly purified batches of single-wall carbon nanotubes (SWCNTs) have shown promise

as superior alternatives to the graphitic

carbon-black anode materials heretofore used in rechargeable thin-film

lithium power cells. The basic idea underlying the experiments is that relative

to a given mass of graphitic carbonblack anode material, an equal mass of

SWCNTs can be expected to have

greater lithium-storage and charge/discharge capacities. The reason for this

expectation is that whereas the microstructure and nanostructure of a

graphitic carbon black is such as to

make most of the interior of the material inaccessible for intercalation of

lithium, a batch of SWCNTs can be

made to have a much more open microstructure and nanostructure, such

Specific Capacity of a carbon-nanotube anode material as a function of cycle number was calculated

from charge and discharge times measured in galvanostatic cycling.

0

0

1

2

3

4

5 10 15

Cycle Number

Specific Capacity, Ah/g

20 25 30

Single-Wall Carbon Nanotube Anodes for Lithium Cells 

Capacities are greater than those of graphite anodes. 

John H. Glenn Research Center, Cleveland, Ohio 

Materials

Microsphere insulation panels (MIPs)

have been developed as lightweight, longlasting replacements for the foam and

vacuum-jacketed systems heretofore used

for thermally insulating cryogenic vessels

and transfer ducts. Whether preformed

or applied in place, foam insulation deteriorates fairly rapidly: on cryogenic transfer lines, it has a life expectancy of about

three years. Vacuum-jacketed insulation is

expensive and heavy. For both foam and

vacuum-jacketed insulation, intensive

maintenance is necessary to keep performance at or near its original level. Relative to a polyurethane foam insulation

panel, a comparable MIP offers greater

thermal performance and longer service

life at approximately the same initial cost.

The microsphere core material of a typical MIP consists of hollow glass bubbles,

which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials.

In particular, a core filling of glass microspheres has high crush strength and low

density, is noncombustible, and performs

well in soft vacuum. A typical MIP includes microspheres in an evacuated

space between flexible vacuum-barrier

layers made of a multilayer polyesterbased laminate [Mylar® 250SBL300 (or

equivalent)]. Included in the laminate

are several non-foil layers that serve as barriers to permeation by water vapor and

other atmospheric gases. The polyesterbased laminate material has a projected

life in excess of 20 years.

An MIP can be made in clamshell-like

halves that can be fitted into a cryogenic

vessel or transfer duct. In general, MIPs

can be applied to transfer ducts along

with jacketing materials conventionally

used on foam insulation, and can be installed by use of essentially the same techniques used to install preformed foam insulation. On the basis of tests according to

standards C518 and C177 of the American Society for Testing and Materials, the

thermal performance of a flexible vacuum-barrier MIP is about two times better

than that of a comparable polyurethane

foam insulation panel.

This work was done by R. Mohling, M.

Allen, and R. Baumgartner of Technology

Applications, Inc. for Kennedy Space Center. For further information, contact Rolf

Baumgartner at (303) 443-2262 x115 or

rbaumga@techapps.com.

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Technology Applications, Inc.

5700 Flatiron Parkway, #5701A 

Boulder, CO 80301-5733

Refer to KSC-12675, volume and number

of this NASA Tech Briefs issue, and the

page number.

Microsphere Insulation Panels

Thermal performance and lifetime exceed those of foam insulation.

John F. Kennedy Space Center, Florida
18 NASA Tech Briefs, June 2006

that most of the interior of the material

is accessible for intercalation of lithium.

Moreover, the greater accessibility of

SWCNT structures can be expected to

translate to greater mobilities for ion-exchange processes and, hence, an ability

to sustain greater charge and discharge

current densities. 

For the experiments, soot containing

carbon nanotubes was produced by laser

vaporization of a graphite target containing 1.2 atomic percent Ni/Co in an

argon atmosphere at a pressure of 500

torr (≈ 67 kPa) at a temperature of 1,200

°C. The soot was purified by refluxing in

nitric acid at a temperature of 125 °C followed by annealing in oxygen at 550 °C

for 30 minutes. By means of scanning

electron microscopy, transmission electron microscopy, ultraviolet-visible spectrophotometry, and thermogravimetric

analysis, 99 weight percent of the purified soot was found to consist of SWCNTs. The specific surface area of the purified material, as measured by use of

the Brunauer, Emmett, and Teller

(BET) technique based on adsorption of

nitrogen, was found to be 1,200 m2

/g —

much greater than the specific surface

areas of several other carbonaceous

anode materials that were also subjected

to the BET test. 

Anodes were fabricated by casting,

onto copper foils, thin films of the purified SWCNT material dispersed at a concentration of 5 weight percent in

poly(vinylidiene fluoride). The anodes

were incorporated into standard threeelectrode test cells along with lithium-foil

counter and reference electrodes and an

electrolyte comprising 1.0 M LiPF6 in a

solution of ethylene carbonate (2 parts by

volume) and dimethyl carbonate (1 part

by volume). Over-potentials for interaction of the anodes with lithium and

lithium capacities of the anodes were

measured by use of cyclic voltammetry

and galvanostatic cycling, respectively. 

The figure shows representative

charge and discharge capacities determined from the measurements. The

plotted values show a high degree of reversibility after the initial cycle. The

specific capacity after 30 cycles was

found to be about 1.33 Ah/g — almost

3 times the generally accepted value

(0.45 Ah/g) for graphite. 

This work was done by Aloysius F. Hepp

of Glenn Research Center; Ryne Raffaelle and Tom Gennett of Rochester Institute of Technology; Prashant Kumta and

Jeff Maranchi of Carnegie-Mellon University; and Mike Heben of National Renewable

Energy Laboratory. Further information is

contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center,

Commercial Technology Office, Attn: Steve

Fedor, Mail Stop 4–8, 21000 Brookpark

Road, Cleveland, Ohio 44135. Refer to

LEW-17356-1 

Tantalum-Based Ceramics for Refractory Composites

Compositions can be graded from porous substrates to impervious outer layers.

Ames Research Center, Moffett Field, California

A family of tantalum-based ceramics

has been invented as ingredients of

high-temperature composite insulating

tiles. These materials are suitable for

coating and/or permeating the outer

layers of rigid porous (foamlike or fibrous) ceramic substrates to (1) render

the resulting composite ceramic tiles

impervious to hot gases and (2) enable

the tiles to survive high heat fluxes at

temperatures that can exceed 3,000 °F

(≈1,600 °C). Originally intended for use

on the future space exploration vehicles, insulating tiles made with these materials may also be useful in terrestrial

applications (e.g., some industrial

processes) in which there are requirements to protect against flows of hot, oxidizing gases.

The starting ingredients of a ceramic

of this invention are the following:

• Tantalum disilicide (TaSi2), which can

act as either an emittance agent or a

matrix material, depending upon the

overall composition;

• Molybdenum disilicide (MoSi2), which,

depending on the overall composition,

acts as a secondary emittance agent or

as an oxygen getter (to inhibit the oxidation of tantalum within the finished

composite);

• A borosilicate glass (B2O3·SiO2), which

acts as a source of boron and may, depending on the overall composition,

act as an alternative matrix; and

• Silicon hexaboride (SiB6), which acts as

a processing aid by facilitating sintering

of the aforementioned ingredients.

These ingredients are milled together

in ethanol, and the resulting slurry is

sprayed or painted onto a porous ceramic substrate. The underlying layers

(sub-layers) of different compositions

are used to integrate the outer layer

(coating) with a wide variety of porous

substrate materials. For this purpose, infiltration of these compositions into the

substrate results in a functional gradient

system that accounts for the difference

in the coefficient of thermal expansion

(CTE) between coating and substrate.

The preferred composition for such underlying layers are in the approximate

range of 20 to 60 weight percent of

MoSi2, 0 to 60 weight percent of TaSi2,

40 to 80 weight percent of borosilicate

glass, and 1 to 5 percent of SiB6. The ingredients are then sintered by heating

the treated substrate at atmospheric

pressure at either a temperature of 2,225 °F

(≈1,218 °C) for 90 minutes or a temperature of 2,400 °F (≈1,316 °C) for 10 minutes. The milling, coating, and sintering

process conditions are chosen to minimize the undesired oxidation of tantalum compounds.

For an outer coating layer, the preferred

composition is between 20 and 45 weight

percent of borosilicate glass, between 10

and 65 weight percent of TaSi2, between 5

and 30 weight percent of MoSi2, and between 1 and 5 weight percent of SiB6. An

underlying layer or sublayer of different

composition can be used to integrate the

outer layer with the substrate and, for this

purpose, may be allowed to infiltrate to

some small depth below the surface of the

substrate. The preferred composition for

such an underlying layer lies in the approximate range of 20 to 60 weight percent of

A Porous Ceramic Substrate Is Coated with one

or more ceramic layers to render it impervious to

hot gas and increase its ability to withstand high

heat flux.

Porous Ceramic Substrate

High-Emittance, Impervious

Outer Ceramic Coating Layer Ceramic Intermediate

Layer (Optional)

ARC14743-1 ABPI 3-8-04 bs
NASA Tech Briefs, June 2006 19

MoSi2, 40 to 80 weight percent of

B2O3·SiO2, and 1 to 5 percent of SiB6. One

or more intervening layer(s) of intermediate composition(s) could also be included

(see figure). The precise composition of

the sublayer should be chosen to match the

CTE of the substrate, while the compositions of intermediate layers should be chosen to grade the transition from the CTE

and porosity of the substrate to the CTE

and full density of the outer coating layer.

This work was done by David A. Stewart,

Daniel Leiser, Robert DiFiore, and Victor

Katvala of Ames Research Center.

This invention is owned by NASA, and a

patent application has been filed. Inquiries

concerning rights for the commercial use of

this invention should be addressed to the

Ames Technology Partnerships Division at

(650) 604-2954. Refer to ARC-14743-1.

NASA Tech Briefs, June 2006 21

Mechanics

Integral Flexure Mounts for Metal Mirrors for Cryogenic Use

These mounts are compact and relatively inexpensive.

Goddard Space Flight Center, Greenbelt, Maryland

Semi-kinematic, six-degree-of-freedom

flexure mounts have been incorporated

as integral parts of metal mirrors designed to be used under cryogenic conditions as parts of an astronomical instrument. The design of the mirrors and

their integral flexure mounts can also be

adapted to other instruments and other

operating temperatures. In comparison

with prior kinematic cryogenic mirror

mounts, the present mounts are more

compact and can be fabricated easily

using Ram-EDM (electrical discharge

machining) process.

The mirrors are designed to be

mounted on an optical bench. To prevent bimetallic stresses that would arise

during heating and cooling between

room temperature (≈293 K) and the operating temperature of 80 K, both the

optical bench and the mirrors are made

of aluminum alloy 6061. Also, the mirrors and the bench are subjected to

stress-relief treatments during fabrication to reduce figure errors and alignment changes that could arise upon

cooling from room temperature to the

operating temperature.

Each mirror has a width-to-thickness

ratio of about 6 and is made from a 6061

aluminum alloy substrate. Three tablike

flexures (mounting tabs) are machined

into the rear of the substrate, which is diamond-machined flat to optical tolerances. The mounting tabs flex in six degrees of freedom, minimizing distortion

caused by mounting the mirror on the

bench. A large, thin, one-piece shim is

placed between the rear surface of the

mirror and the bench. The bench interface surface and the bench side of the

shim are lapped flat for smooth, repeatable placement. Three thin, raised

bosses that are flat and coplanar to

within tight tolerances rise from the mirror side of the shim to meet the tabs. For

changes in alignment, the bosses are machined such that the mirror substrate is

always approximately parallel to the

plane that the bosses define. Therefore,

the tabs do not bend in response to

changes in alignment, but flex only to accommodate coplanarity errors in the machining of the three shim bosses. Ideally,

no tab should ever be made to flex more

than ±0.025 mm in translation, but the

tabs are designed to yield an acceptable

figure error for displacements of as

much as ±0.125 mm in all three translational degrees of freedom and/or ±0.1°

in all three rotational degrees of freedom.

This work was done by S. Wahid Zewari,

Jason E. Hylan, Sandra M. Irish, and Raymond G. Ohl of Goddard Space Flight Center and Shelly B. Conkey of Swales Aerospace,

Inc. Further information is contained in a

TSP (see page 1).

GSC-14969-1

An effort is underway to develop

processes for making templates that

could be used as deposition molds and

etching masks in the fabrication of devices containing arrays of nanowires

and/or nanoconduits. Examples of

such devices include thermoelectric

devices, nerve guidance scaffolds for

nerve repair, photonic-band-gap devices, filters for trapping microscopic

particles suspended in liquids, microfluidic devices, and size-selective

chemical sensors. The technology is

an extension of previous work conducted by JPL, UCSD (University of

California, San Diego), and Paradigm

Optics Inc., which developed a process

to fabricate macroporous scaffolds for

spinal-cord repair.

Highly-ordered, optical-fiber arrays

consisting of dissimilar polymers comprise the template technology. The selective removal of the fiber cores in

specific solvents creates the porous

templates to be filled with a “topdown” deposition process such as electrochemical deposition, sputter deposition, molecular beam epitaxy, and

the like.

Typically, the fiber bundles consist of

polystyrene (PS) fiber cores, which are

clad with varying thickness poly(methyl

methacrylate) (PMMA). When

arranged in hexagonal, close-packed

configuration and pulled, the fibers

form highly-ordered arrays comprised of

PS fiber cores surrounded by a continuous matrix of PMMA. The ratio of

PMMA cladding thickness to PS core diameter determines the spacing between

PS fiber cores and typically ranges from

3:1 to 1:1.

Essentially, the simultaneous heating

and drawing or pulling in the longitudinal direction of polymer-fiber arrays

fuses the fibers to-gether. Since the fusing process is a constant volume process,

a lateral or cross-section reduction is accompanied by a commensurate increase

in length. Thus, the degree of pulling

determines the final core dimensions.

Compared to previous

work, where the fiber cores

were in the range of 100 to 200

microns, the extent of pulling

was significantly increased,

thus resulting in a significant

reduction in feature dimensions. The scanning electron

microscope (Figure 1) image

reveals the close packed array

100-nm diameter holes etched

in a PMMA matrix (center

image). The background

image indicates that the hole

monodispersity and order is

maintained over relatively

large areas. The original template length or fiber length

was greater than 1 cm and the

cross sectional dimension was

1 cm by 0.4 cm (Figure 2). In

principle, the depth of the

holes could be far greater than

1 mm, which could result in

Figure 1. An Image from a scanning electron microscope shows the array of 100-nm diameter holes

etched in a PMMA matrix.

NPO41906 fig 1 ABPI

2-27-06 CC

NASA Tech Briefs, June 2006 23

Manufacturing & Prototyping

Templates for Fabricating Nanowire/Nanoconduit-Based

Devices

Prior templating processes are being extended to finer spatial resolutions.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Figure 2. The Nanotemplate, approximately 1/2×1/2×1/8 inch

(12.7×12.7×3.2 mm), contains about 60 fibers.

NPO41906 fig 2 ABPI

2-27-06 CC
24 NASA Tech Briefs, June 2006

A proposed noninvasive method of

monitoring the cure path and the state

of cure of an epoxy or other resin involves measurement of the concentration(s) of one or more compound(s) in

the vaporous effluent emitted during

the curing process. The method is based

on the following general ideas:

• The concentrations of the effluent

compounds in the vicinity of the curing resin are approximately proportional to the instantaneous rate of curing.

• As curing proceeds at a given temperature, subsequent decreases in the concentrations are indicative of approaching completion of cure; that is, the

lower are the concentrations, the more

nearly complete is the cure.

The method could be utilized as the

basis of a means of controlling the curing process to optimize the properties of

the cured resin. It also could be utilized

to minimize the cost of the curing

process by ensuring a complete cure

without the need to provide for excess

curing time as margin against uncertainty in a prior estimate of required curing time.

A system to implement the method

would include a sensor that produces

electronic readouts of the concentrations of effluent compounds of interest.

This sensor could be any of a variety of

instruments, ranging from general-purpose full-size laboratory instruments capable of rapidly analyzing many compounds to microelectromechanical

(MEMS) devices designed to detect effluent compounds specific to one epoxy.

Either continuously or at regular intervals, the sensor would sample the effluent. Depending on the specific curing

process, the sampling could occur at

room temperature, at elevated temperature, under vacuum, or at atmospheric

pressure: for example, in a case involving curing in a vacuum/heating apparatus, the sensor could be placed in the

unheated tube from the vacuum bag to

the vacuum pump.

The concentration(s) of the compound(s) of interest, and, thus, the rate

of production of effluent would be monitored electronically and digitized to make

a record of the curing process. Once the

concentrations of the effluent compounds of interest decreased to predetermined levels, the cure would be considered complete and the operator would

be so notified by the sensor circuitry. Alternatively, as depicted schematically in

the figure, the sensor could be integrated

into a control loop that would turn off

the curing apparatus upon completion of

the cure. Further, the control loop could

be configured for active control to maintain the rate of curing at a predetermined

level by monitoring the effluent-production rate and automatically adjusting the

temperature and/or the pressure of the

partial vacuum.

This work was done by K. Elliott Cramer,

Daniel F. Perey, and William T. Yost of Langley Research Center. Further information is

contained in a TSP (see page 1).

LAR-16695-1

Curing of Epoxy in a composite patch on an aluminum airframe component would be monitored by

measuring concentrations of vaporous effluent compounds. The measurements could serve as feedback for controlling the vacuum pump and the heater.

Heater

Control

Vacuum

Pump

Chemical Sensor

With Electronic

Readout

Vent

Control

Computer

Vacuum/Heating

Apparatus

Tube

Epoxy/Fiber

Composite Repair Patch

Aluminum

Airframe Component

LAR-16695-1

ABPI 10-9-05 es

Measuring Vapors To Monitor the State of Cure of a Resin

Excess curing time would no longer be needed as margin against uncertainty.

Langley Research Center, Hampton, Virginia

features with aspect ratios (length/diameter) in the 1,000 to 10,000 range.

This work was done by Jeffrey Sakamoto of

Caltech for NASA’s Jet Propulsion Laboratory, and Todd Holt and David Welker of

Paradigm Optics, Inc. Further information is

contained in a TSP (see page 1).

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Innovative Technology Assets Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

(818) 354-2240

Refer to NPO-41906, volume and number

of this NASA Tech Briefs issue, and the

page number.
NASA Tech Briefs, June 2006 25

An electrochemical cell for making

corrosion measurements has been designed to prevent or reduce crevice corrosion, which is a common source of

error in prior such cells. In a typical prior

corrosion cell, crevice corrosion occurs at

an interface between a material specimen, an electrolyte, and a specimenmounting fixture. Crevice corrosion significantly alters current and voltage

responses, thereby generating errors in

the determination of both the thermodynamic and kinetic aspects of corrosion.

The present cell (see figure) includes

an electrolyte reservoir with O-ring-edged

opening at the bottom. In preparation

for a test, the reservoir, while empty, is

pressed down against a horizontal specimen surface to form an O-ring seal. A

purge of air or other suitable gas is begun

in the reservoir, and the pressure in the

reservoir is regulated to maintain a partial vacuum. While maintaining the

purge and partial vacuum, and without

opening the interior of the reservoir to

the atmosphere, the electrolyte is

pumped into the reservoir. The reservoir

is then slowly lifted a short distance off

the specimen. The level of the partial vacuum is chosen such that the differential

pressure is just sufficient to keep the electrolyte from flowing out of the reservoir

through the small O-ring/specimen gap.

Electrochemical measurements are then

made. Because there is no gasket (and,

hence, no crevice between the specimen

and the gasket), crevice corrosion is unlikely to occur.

This cell is easy to operate, uses a relatively small volume (10 to 25 mL) of electrolyte, accommodates specimens of various sizes, does not leave rubber O-ring

residues on specimens, is inherently suitable for testing with electrolytes that must

be purged with gases, and can easily be

cleaned. Simple modifications can be

performed to enable use of this cell in

special crevice-free corrosion tests — for

example, tests for determining critical

pitting temperatures.

Inasmuch as the purge gas can quickly

diffuse into the electrolyte, careful selection of the purge gas is necessary to ensure reliable results. Water-line corrosion

could introduce small errors into some

measurements.

This work was done by Andrew P. Bonifas

and Luz M. Calle of Kennedy Space Center and Paul E. Hintze funded by the National Research Council at Kennedy Space

Center. Further information is contained in a

TSP (see page 1).

KSC-12765

Reservoir

Partial Vacuum

and

Gas Purge

Electrolyte

Partial Vacuum

and

Gas Purge

O Ring Pressure

Specimen BEFORE TEST DURING TEST

KSC-12765

ABPI 7-18-05 es

Physical Sciences

Partial-Vacuum-Gasketed Electrochemical Corrosion Cell

This cell is designed to reduce the incidence of crevice corrosion.

John F. Kennedy Space Center, Florida

Differential Pressure between the atmosphere and the partial vacuum above the reservoir keeps the

electrolyte in the reservoir when the reservoir is lifted a short distance off the specimen. The gap between the bottom of the reservoir and the specimen is exaggerated here for clarity.

Theodolite ring lights have been invented to ease a difficulty encountered

in the well-established optical-metrology practice of using highly reflective

spherical tooling balls as position references. As described in more detail

below, a theodolite ring light is attached to a theodolite or telescope and

used to generate a visible target on a

tooling ball.

A common technique for aiming an

instrument (specifically, a theodolite or

an alignment telescope) precisely at the

center of a tooling ball involves the use

of an autocollimating device. This technique is less than ideal because the reflection from the ball is demagnified by

the spherical surface of the ball. The demagnification makes it extremely difficult to resolve the reflection and align it

accurately within the cross hairs of the

Theodolite Ring Lights

These lights facilitate the use of spherical tooling balls as position references.

Goddard Space Flight Center, Greenbelt, Maryland
26 NASA Tech Briefs, June 2006

instrument. This difficulty increases

with increasing distance and with decreasing size of the ball. Also, the autocollimating device adds greatly to the

cost of the instrument.

A theodolite ring light produces a

more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very

bright light source that is well centered

on the optical axis of the instrument. It

can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter. It can be quickly

mounted on or removed from the instrument. No calibration or modification of

the instrument is needed. Moreover, the

theodolite ring light does not reduce the

field of view of the instrument and does

not scatter light into the objective-lens

housing of the instrument.

A theodolite ring light consists of a

number of light-emitting diodes (LEDs)

placed at equal angular intervals in a ring

sized to fit snugly over the objective lens

of the instrument. The prototype theodolite ring light, shown in the figure, includes eight 5.5-candela blue light-emitting diodes (LEDs) mounted in a ring

fabricated of black polyacetal. The LEDs

are powered by two D-size alkaline cells.

In general, the number, brightness, and

color of the LEDs can be chosen according to the conditions prevailing in a given

measurement environment.

The prototype has been used to locate

tooling balls of 0.5-in. (1.27-cm) and 1-

in. (2.54-cm) diameter at distances from

10 to 25 ft (about 3 to 7.6 m). Operators

consistently achieved accuracy and repeatability at or near the limiting resolution of the instrument. These results

were significantly better than those typically obtained with conventional targets.

In addition, the extreme demagnification by the small spherical target surfaces eliminated the need for calibration

and for fabricating the ring to close tolerances.

This work was done by David Clark of

Goddard Space Flight Center. For further information, contact the Goddard Innovative Partnerships Office at (301) 286-

5810.

GSC-14898-1

GSC-14898-1

ABPI

11-1-05 ca

The Prototype Theodolite Ring Light is shown here mounted on the objective-lens housing of a

theodolite.
NASA Tech Briefs, June 2006 27

Information Sciences

Integrating Terrain Maps Into a Reactive Navigation Strategy

Traversability of terrain is taken into account as an integral part of navigation.

NASA’s Jet Propulsion Laboratory, Pasadena, California

An improved method of processing information for autonomous navigation of

a robotic vehicle across rough terrain involves the integration of terrain maps

into a reactive navigation strategy. Somewhat more precisely, the method involves

the incorporation, into navigation logic,

of data equivalent to regional traversability maps. The terrain characteristic is

mapped using a fuzzy-logic representation of the difficulty of traversing the terrain. The method is robust in that it integrates a global path-planning strategy

with sensor-based regional and local navigation strategies to ensure a high probability of success in reaching a destination

and avoiding obstacles along the way. The

sensor-based strategies use cameras

aboard the vehicle to observe the regional terrain, defined as the area of the

terrain that covers the immediate vicinity

near the vehicle to a specified distance a

few meters away. The method at an earlier stage of development was described

in “Navigating a Mobile Robot Across

Terrain Using Fuzzy Logic” (NPO21199), NASA Tech Briefs, Vol. 27, No. 2

(February 2003), page 5a. A recent update on the terrain classification stage of

the method was reported in “Quantifying

Traversability of Terrain for a Mobile

Robot” (NPO-30744), NASA Tech Briefs,

Vol. 29, No. 7 (July 2005), page 56. To recapitulate: The basic building blocks of

the method are three behaviors that

focus on successively smaller spatial scales

and are integrated (in the sense of

blended) through gains or weighting factors to generate speed and steering commands. The weighting factors are generated by fuzzy logic rules that take account

of the current status of the vehicle.

At the present state of development,

the three behaviors are denoted as a mapbased seek-waypoint behavior, a sensorbased traverse-terrain behavior, and a

sensor-based avoid-obstacle behavior (see

figure). Navigation is initiated by a global

path-planning algorithm, which generates a sequence of waypoints that define

an optimal path that passes through safe

(that is, sufficiently traversable) regions

of the terrain from a starting point to a

destination. The waypoints are fed to the

map-based seek-waypoint behavior,

which, as its name suggests, seeks to direct the vehicle safely from the starting location to a waypoint. The sensor-based

traverse-terrain behavior determines the

safest regional segment to traverse on the

basis of information from regional terrain images acquired by the cameras. The

sensor-based avoid-obstacle behavior involves the use of local-obstacle information from the images to develop steering

and speed commands to maneuver the

vehicle around the obstacles.

This work was done by Ayanna Howard,

Barry Werger, and Homayoun Seraji of Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1).

NPO-30794

The Navigation-System Architecture implements three behaviors that focus on successively smaller spatial scales. These behaviors are integrated to enable safe traversal of rough terrain from a starting point

to a destination.

Map-Based

Seek-Waypoint

Behavior

Waypoints From a Global

Path-Planning Algorithm

Behavior-Based Navigator

Sensor-Based

Traverse-Terrain

Behavior

Speed and

Steering

Commands

Sensor-Based

Avoid-Obstacle

Behavior

Interrogation

Regional

Terrain Map

Assessment of

Traversability

Detection of

Obstacles

Regional

Terrain

Local

Obstacle

NPO30794

ABPI

10-7-03 bs

Reducing Centroid Error Through Model-Based Noise Reduction

Corrections are made for bias and noise.

NASA’s Jet Propulsion Laboratory, Pasadena, California

A method of processing the digitized

output of a charge-coupled device

(CCD) image detector has been devised

to enable reduction of the error in computed centroid of the image of a point

source of light. The method involves

model-based estimation of, and correction for, the contributions of bias and

noise to the image data. The method

could be used to advantage in any of a variety of applications in which there are

requirements for measuring precise locations of, and/or precisely aiming optical

instruments toward, point light sources.

The principal sources of centroid

error are bias and noise in the outputs

from the pixels of the CCD. Noise consists mainly of fixed components (readout noise and noise from dark current)

and variable components (pixel defects

and shot noise from background light).
28 NASA Tech Briefs, June 2006

Bias is caused mainly by stray light and

nonuniform distribution of light in a

background image.

In the present method, prior to normal operations of the CCD, one measures the point-spread function (PSF) of

the telescope or other optical system

used to project images on the CCD. The

PSF is used to construct a database of

spot models representing the nominal

CCD pixel outputs for a point light

source projected onto the CCD at various positions incremented by small fractions of a pixel (see figure).

During normal operation of the

CCD, the centroid of the image of a

point source of light is initially computed from the digitized CCD pixel

outputs in the conventional way.

However, this initial computation of

the centroid is used to retrieve the

corresponding spot model that was

constructed earlier. Then the boundary between noise and signal is determined by comparing the spot model

with the CCD pixel outputs. Pixel positions of same pixel value of the spot

model and the image data in the

background area are defined as the

boundary. All pixels of the image data

beyond this boundary are set to zero.

This effectively removes the noise

and bias in the subsequent centroid

estimation from the corrected image

data.

This work was done by Shinhak Lee of Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1).

NPO-30585

Spot Models are constructed from the measured PSF. The spot models are thereafter used in processing digitized CCD outputs to correct for bias and noise to refine centroid estimates.

Model-Based Noise Reduction

Determine PSF of

Optical System

Construct the 

Sampled Spot Model

at Every 10th or 1/20th

Pixel Movement

Database of 

Spot Models

NPO-30585 

ABPI

06-03-04 LE

Adaptive Modeling Language (AML),

developed by TechnoSoft, Inc., is the underlying language of an object-oriented,

multidisciplinary, knowledge-based engineering framework. TechnoSoft is a leading provider of object-oriented modeling

and simulation technology used for commercial and defense applications. AML

offers an advanced modeling paradigm

with an open architecture, enabling the

automation of the entire product development cycle, integrating product configuration, design, analysis, visualization,

production planning, inspection, and

cost estimation.

The AML framework is truly adaptive.

Its successful history includes a wide variety of defense and commercial applications including aerospace, automotive,

and capital equipment.

TechnoSoft has worked with the Vehicle Analysis Branch (VAB) at NASA

LaRC on the development of the Collaborative Hypersonic Airbreathing Vehicle

Environment (CoHAVE) built using

AML. The collaborative enterprise environment of CoHAVE and its criteriamanagement environment are applicable to the design of NASA, military, and

private commercial vehicles. 

CoHAVE is applicable to the Reusable

Space Transportation System’s product

area for evaluating the architectures of

the Space Transportation Architecture

Studies and Second Generation RLV

Studies. Elements of this architecture include enhanced Shuttle, Reusable Two

Stage to Orbit, and Venture Star (an

SSTO design). Complementary to these

delivery vehicles are Orbital Transfer Vehicles, Crew Transfer and Crew-Cargo

Transfer Vehicles, and the Reusable First

Stage Booster for Space Shuttle Upgrades. CoHAVE is platform independent and enables multiple users to collaborate across geographically-distributed,

heterogeneous workstations. CoHAVE

provides a comprehensive environment

that facilitates the performance of concurrent engineering of hypersonic airbreathing vehicles at a level not currently

available. 

Recently, CoHAVE has been extended

to incorporate models for other applications such as re-entry vehicles. Since the

environment now includes vehicles other

than traditional hypersonic airbreathing

vehicles, the name has morphed into the

Advanced Vehicle Integration and Synthesis Environment (AdVISE). 

This work was done by Adel Chemaly of

TechnoSoft, Inc. under a NASA Small Business Innovation Research (SBIR) contract

monitored by Langley Research Center. For

further information, contact:

Mr. Adel Chemaly 

TechnoSoft, Inc.

11180 Reed Hartman Hwy.

Cincinnati, OH 45242 

Phone No.: (513) 985-9877

E-mail: adel.chemaly@technosoft.com

Web site: www.technosoft.com.

Refer to SBIR-0012, volume and number of

this NASA Tech Briefs issue, and the page

number.

Adaptive Modeling Language and Its Derivatives

Modeling language enables automation of the entire product development cycle.

TechnoSoft, Inc., Cincinnati, Ohio
NASA Tech Briefs, June 2006 29

Stable Satellite Orbits for

Global Coverage of the

Moon

A document proposes a constellation

of spacecraft to be placed in orbit

around the Moon to provide navigation

and communication services with global

coverage required for exploration of the

Moon. There would be six spacecraft in

inclined elliptical orbits: three in each of

two orthogonal orbital planes, suggestive

of a linked-chain configuration. The orbits have been chosen to (1) provide

99.999-percent global coverage for ten

years and (2) to be stable under perturbation by Earth gravitation and solar-radiation pressure, so that no deterministic

firing of thrusters would be needed to

maintain the orbits. However, a minor

amount of orbit control might be

needed to correct for such unmodeled

effects as outgassing of the spacecraft.

This work was done by Todd Ely of Caltech

and Erica Lieb of ASRC for NASA’s Jet

Propulsion Laboratory. Further information

is contained in a TSP (see page 1). NPO-42722

Low-Cost Propellant Launch

From a Tethered Balloon

A document presents a concept for

relatively inexpensive delivery of propellant to a large fuel depot in low

orbit around the Earth, for use in rockets destined for higher orbits, the

Moon, and for remote planets. The

propellant is expected to be at least 85

percent of the mass needed in low

Earth orbit to support the NASA Exploration Vision. The concept calls for

the use of many small (≈10 ton) spinstabilized, multistage, solid-fuel rockets to each deliver ≈250 kg of propellant. Each rocket would be winched up

to a balloon tethered above most of

the atmospheric mass (optimal altitude 26 ±2 km). There, the rocket

would be aimed slightly above the

horizon, spun, dropped, and fired at a

time chosen so that the rocket would

arrive in orbit near the depot. Small

thrusters on the payload (powered, for

example, by boil-off gasses from cryogenic propellants that make up the

payload) would precess the spinning

rocket, using data from a low-cost inertial sensor to correct for small aerodynamic and solid rocket nozzle misalignment torques on the spinning

rocket; would manage the angle of attack and the final orbit insertion burn;

and would be fired on command from

the depot in response to observations

of the trajectory of the payload so as to

make small corrections to bring the

payload into a rendezvous orbit and

despin it for capture by the depot. The

system is low-cost because the small

rockets can be mass-produced using

the same techniques as those to produce automobiles and low-cost munitions, and one or more can be

launched from a U.S. territory on the

equator (Baker or Jarvis Islands in the

mid-Pacific) to the fuel depot on each

orbit (every 90 minutes, e.g., any multiple of 6,000 per year).

This work was done by Brian Wilcox of

Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a TSP (see page 1). NPO-42007

Books & Reports


National Aeronautics and

Space Administration