Technology Focus

Computers/Electronics

Software

Materials

Mechanics

Machinery/Automation

Manufacturing

Bio-Medical

Physical Sciences

Information Sciences

Books and Reports

08-05 August 2005

NASA Tech Briefs, August 2005 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 

Commercial Technology Team, its documents, and services is also available at the same facility or on the 

World Wide Web at www.nctn.hq.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

Ray P. Turcotte

(757) 864-8881

r.p.turcotte@larc.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

Frank Schowengerdt

Innovative Partnerships Program

(Code TD)

(202) 358-2560

fschowen@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: 

Data Acquisition

5 Hidden Identification on Parts: Magnetic

Machine-Readable Matrix Symbols

6 System for Processing Coded OFDM Under

Doppler and Fading

7 Multipurpose Hyperspectral Imaging System

9 Electronics/Computers

9 Magnetic-Flux-Compensated Voltage Divider

9 High-Performance Satellite/ Terrestrial-Network

Gateway

10 Internet-Based System for Voice Communication

With the ISS

11 Stripline/Microstrip Transition in Multilayer Circuit

Board

12 Dual-Band Feed for a Microwave Reflector

Antenna

13 Software

13 Quadratic Programming for Allocating Control

Effort

13 Range Process Simulation Tool

13 Simulator of Space Communication Networks

13 Computing Q-D Relationships for Storage of

Rocket Fuels

14 Contour Error Map Algorithm

14 Portfolio Analysis Tool

14 Simulator of Space Communication Networks

15 Materials

15 Glass Frit Filters for Collecting Metal Oxide

Nanoparticles

15 Anhydrous Proton-Conducting Membranes for

Fuel Cells

17 Manufacturing

17 Portable Electron-Beam Free-Form Fabrication

System

19 Bio-Medical

19 Miniature Laboratory for Detecting Sparse

Biomolecules

20 Multicompartment Liquid-Cooling/Warming

Protective Garments

21 Physical Sciences

21 Laser Metrology for an Optical-Path-Length

Modulator

22 PCM Passive Cooling System Containing Active

Subsystems

22 Automated Electrostatics Environmental Chamber

23 PCM Passive Cooling System Containing Active

Subsystems

24 Estimating Aeroheating of a 3D Body Using a 2D

Flow Solver

25 Information Sciences

25 Artificial Immune System for Recognizing Patterns

26 Computing the Thermodynamic State of a

Cryogenic Fluid

27 Safety and Mission Assurance Performance

Metric

29 Books & Reports

29 Magnetic Control of Concentration Gradient in

Microgravity

29 Avionics for a Small Robotic Inspection Spacecraft

29 Simulation of Dynamics of a Flexible Miniature

Airplane

08-05 August 2005

NASA Tech Briefs, August 2005 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, August 2005 5

Technology Focus: Data Acquisition

Hidden Identification on Parts: Magnetic Machine-Readable

Matrix Symbols

These symbols could be read even when covered with paint.

Marshall Space Flight Center, Alabama

Have you ever seen a piece of spaceflight hardware? When you do, you will

notice some letters and numbers etched

or inscribed on it. All NASA parts have

identification, usually expressed in terms

of part number, serial number, and the

like. In most cases, this identification is

permanently marked directly on the part

for tracking throughout its life cycle. The

recently approved NASA Technical Standard 6002 and Handbook 6003 (found at

http://standards.nasa.gov) added the matrix symbol to the identification scheme

as shown in Figure 1. This put a checkerboard bar code on the part so that an optical scanner could read it. The intent

was to make tracking parts as easy as

checking out at the grocery store. The

system works well as long as the matrix

symbol is visible.

But what if the matrix symbol identification gets covered with paint or a

similar coating? NASA has developed a

method for reading the matrix symbol

through up to 15 mils (25 μm) of paint

(5 or 6 layers). This method of part

identification involves coating selected

patches on the objects with magnetic

materials in matrix symbol patterns

and reading the patterns by use of magneto-optical imaging equipment. The

hand-held magnetic scanner, shown in

Figure 2, is easy to use and is commercially available through a NASA licensee. It decodes the matrix symbol

just like any other scanner. The magnetic marks can be read under conditions that would render optical methods useless. For example, the magnetic

scanner can read magnetic marks in

the dark or under bright ambient light

that might interfere with optical reading of visible marks, symbols that are

obscured by discoloration or contamination, in addition to symbols that are

covered by paint. Furthermore, inasmuch as magnetic marks can be hidden from unaided view, they are less

likely to be deliberately damaged or destroyed. They can even be hidden deliberately for security reasons.

Magnetic material can be applied as

Figure 1. A Space Shuttle Component shows matrix symbol identification markings. viscous ink or paste and even can be

Figure 2. This Hand-Held Scanner would contain all the equipment (except a source of electric power) needed to read and decode magnetic matrix symbols.
6 NASA Tech Briefs, August 2005

mixed with spray paint. The magnetic

material should be one of high retentivity and high coercivity. The matrix symbol pattern can be defined by use of a

stencil, or recesses to hold the magnetic

material in the matrix symbol pattern

can be formed by laser engraving, machine engraving, micro-abrasive blasting, laser etching, or any other suitable

marking method. If the magnetic material as applied is not magnetized

strongly enough to enable reliable detection over time, it can be magnetized

again by use of a permanent magnet or

electromagnet.

Bar codes were seldom seen before

1975 but are now common in every commercial outlet. They are on tags and labels of virtually every product. Likewise,

direct part marking is now being popularized for tracking things that cannot be labeled. NASA tracks parts using direct part

marking. The Department of Defense revised MIL STD 130 to include matrix symbols for direct part marking, and the automotive industry now complies with its

B-17 specification for application of matrix symbols on many automobile parts.

Now all those little marks that get covered

with paint, whether they are on your automobile, jet fighter, weapon, or space shuttle, can be read with ease. 

This work was done by Harry F. Schramm

and Clyde S. Jones of Marshall Space Flight

Center; Donald L Roxby and James D. Teed

of Rockwell International Corp.; and

William C. L. Shih, Gerald L. Fitzpatrick,

and Craig Knisely of PRI Research and Development Corp.

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 MFS31013/768.

System for Processing Coded OFDM Under Doppler and Fading

Advanced techniques would help to realize the anti-fading potential of OFDM.

NASA’s Jet Propulsion Laboratory, Pasadena, California

An advanced communication system

has been proposed for transmitting and

receiving coded digital data conveyed as a

form of quadrature amplitude modulation (QAM) on orthogonal frequency-division multiplexing (OFDM) signals in the

presence of such adverse propagationchannel effects as large dynamic Doppler

shifts and frequency-selective multipath

fading. Such adverse channel effects are

typical of data communications between

mobile units or between mobile and stationary units (e.g., telemetric transmissions from aircraft to ground stations).

The proposed system incorporates novel

signal processing techniques intended to

reduce the losses associated with adverse

channel effects while maintaining compatibility with the high-speed physical layer

specifications defined for wireless localarea networks (LANs) as the standard

802.11a of the Institute of Electrical and

Electronics Engineers (IEEE 802.11a).

OFDM is a multi-carrier modulation

technique that is widely used for wireless

transmission of data in LANs and in metropolitan area networks (MANs). OFDM

has been adopted in IEEE 802.11a and

some other industry standards because it

affords robust performance under frequency-selective fading. However, its intrinsic frequency-diversity feature is

highly sensitive to synchronization errors; this sensitivity poses a challenge to

preserve coherence between the component subcarriers of an OFDM system in

order to avoid intercarrier interference

in the presence of large dynamic

Doppler shifts as well as frequency-selective fading. As a result, heretofore, the

use of OFDM has been limited primarily

to applications involving small or zero

Doppler shifts. The proposed system includes a digital coherent OFDM communication system that would utilize enhanced 802.1la-compatible signal-processing

algorithms to overcome effects of frequency-selective fading and large dynamic Doppler shifts. The overall transceiver design would implement a

two-frequency-channel architecture (see

figure) that would afford frequency diversity for reducing the adverse effects of

multipath fading. By using parallel concatenated convolutional codes (also

known as Turbo codes) across the dualchannel and advanced OFDM signal processing within each channel, the proposed system is intended to achieve at

least an order of magnitude improvement in received signal-to-noise ratio

under adverse channel effects while preserving spectral efficiency.

OFDM-Based

Modulator

Transmitter

Frequency

Channel 1

Frequency

Channel 2

OFDM-Based

Modulator

CrossChannel

(Turbo)

Encoder

Input

Bit Stream

Output

Bit Stream

OFDM-Based

Demodulator

OFDM-Based

Demodulator

Receiver

Diversity

Combiner

Iterative

Decoder

A Two-Frequency-Channel, Cross-Coded OFDM System would contain the proposed signal-processing system, parts of which would reside in both transmitting and receiving subsystems.
NASA Tech Briefs, August 2005 7

One of the novel techniques adopted

for the proposed system would be multipass processing of packet preamble for

acquisition of frequencies and timing of

carrier and data symbols. The multipass

approach is intended to eliminate as

much synchronization error as possible

at an early stage of packet preamble processing in order to reduce the inter-carrier interference, which can contribute

significantly to the bit-error rate under

adverse channel conditions.

Another novel signal-processing technique would be joint pilot- and data-aided

channel estimation, tracking, and equalization in each of the two frequency channels. This technique would not only increase the accuracy in the estimate of the

channel effects, but also would support

tracking of dynamic Doppler shifts, resulting in a much improved channel equalization under adverse channel conditions.

Another novel aspect of the design

would be the use of (1) turbo cross-channel coding in the transmitter in conjunction with (2) diversity combining of signals in the receiver. The gain afforded by

this combination of coding and frequency and time diversity would help to

counteract severe fading, especially for

the case when both channels are simultaneously affected by deep fades.

This work was done by Haiping Tsou,

Scott Darden, Dennis Lee, and Tsun-Yee Yan 

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

a TSP (see page 1)

The software used in this innovation is

available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (818) 393-2827. Refer

to NPO-40205.

Multipurpose Hyperspectral Imaging System

Features include high spectral and spatial resolution, without camera/target relative motion.

Marshall Space Flight Center, Alabama

A hyperspectral imaging system of high

spectral and spatial resolution that incorporates several innovative features has

been developed to incorporate a focalplane scanner (U.S. Patent 6,166,373).

This feature enables the system to be used

for both airborne/spaceborne and laboratory hyperspectral imaging with or without

relative movement of the imaging system,

and it can be used to scan a target of any

size as long as the target can be imaged at

the focal plane; for example, automated inspection of food items and identification of

single-celled organisms. The spectral resolution of this system is greater than that of

prior terrestrial multispectral imaging systems. Moreover, unlike prior high-spectralresolution airborne and spaceborne hyperspectral imaging systems, this system does

not rely on relative movement of the target

and the imaging system to sweep an imaging line across a scene.

This compact system (see figure) consists of a front objective mounted at a translation stage with a motorized actuator, and

a line-slit imaging spectrograph mounted

within a rotary assembly with a rear adaptor to a charged-coupled-device (CCD)

camera. Push-broom scanning is carried

out by the motorized actuator which can

be controlled either manually by an operator or automatically by a computer to drive

the line-slit across an image at a focal plane

of the front objective. To reduce the cost,

the system has been designed to integrate

as many as possible off-the-shelf components including the CCD camera and

spectrograph. The system has achieved

high spectral and spatial resolutions by

using a high-quality CCD camera, spectrograph, and front objective lens. Fixtures

for attachment of the system to a microscope (U.S. Patent 6,495,818 B1) make it

possible to acquire multispectral images of

single cells and other microscopic objects.

To make it unnecessary to move the

camera relative to the target or vice versa,

the design of the system provides for lateral motion of the image on the focal

plane. For this purpose, the front lens is

mounted on a translational stage driven

by a computer-controlled motor.

The system also includes a computer

programmed with special-purpose operational software; frame-grabber, and motorcontrol circuit boards connected between

the computer on one hand and the CCD

and motor, respectively, on the other

hand; and light sources. The system can

collect image data in as many as 1,040

spectral bands in the wavelength range

from 400 to 1,000 nm.

The special-purpose operational software is a single computer program that

controls all aspects of the acquisition and

preprocessing of image data, performing

functions that, heretofore, entailed the use

of several different programs: The software

controls the camera, scanning speed, and

start and stop positions, and automatically

drives the motorized actuator in pushThe Main Front Components of the imaging system are shown mounted on the tripod.

CCD Camera

Image Relay/Filter Suite

Lens

Actuator
8 NASA Tech Briefs, August 2005

broom scanning. A user may utilize the

program to invoke the CCD camera’s user

interface for customized configuration.

Different spectral band-pass and spatial resolutions may be changed by different CCD

vertical/horizontal binning factors. A calibration function is implemented for correcting spectral and spatial errors due to

optical distortion of the front objective and

spectrograph. The software then preprocesses the image data into hyperspectral image cubes (three-dimensional arrays

of data indexed according to two spatial coordinates and a spectral coordinate). Next,

the software can perform calibration,

noise-removal, data-formatting, and subsetting operations; correct for spectral distortions; and create headers for image-data

files to be subjected to further processing

by other software (for example, the software described below), as instructed by the

user. The program can also perform some

image-inversion calculations and some statistical analysis of image data, and can detect image saturation.

By suitably modifying the operational

software and adding special-purpose

image-processing software, the system can

be configured for automated inspection of

food items on production lines. An example of this functionality is the development

of a prototype version to process three- or

four-spectral-band images to detect fecal

contamination of poultry carcasses on a

conveyor belt at a rate of 180 carcasses per

minute — about double the rate of a modern poultry-processing line.

This work was done by Chengye Mao, David

Smith, Mark A. Lanoue, Gavin H. Poole, Jerry

Heitschmidt, and Luis Martinez of The Institute for Technology/Provision Technologies;

and William A. Windham, Kurt C. Lawrence,

and Bosoon Park of the Agricultural Research

Service of the United States Department of Agriculture for Marshall Space Flight Center.

For further information, contact the company

at info@pvtech.org.

MFS-31892/3/4/5/6/7
NASA Tech Briefs, August 2005 9

Electronics/Computers

Magnetic-Flux-Compensated Voltage Divider

Spurious voltages generated by lightning and other transient phenomena would be suppressed.

John F. Kennedy Space Center, Florida

A magnetic-flux-compensated voltagedivider circuit has been proposed for

use in measuring the true potential

across a component that is exposed to

large, rapidly varying electric currents

like those produced by lightning strikes.

An example of such a component is a

lightning arrester, which is typically exposed to currents of the order of tens of

kiloamperes, having rise times of the

order of hundreds of nanoseconds. Traditional voltage-divider circuits are not

designed for magnetic-flux-compensation: They contain uncompensated

loops having areas large enough that the

transient magnetic fluxes associated

with large transient currents induce spurious voltages large enough to distort

voltage-divider outputs significantly.

A drawing of the proposed circuit was

not available at the time of receipt of information for this article. What is known

from a summary textual description is that

the proposed circuit would contain a total

of four voltage dividers: There would be

two mixed dividers in parallel with each

other and with the component of interest

(e.g., a lightning arrester), plus two mixed

dividers in parallel with each other and in

series with the component of interest in

the same plane. The electrical and geometric configuration would provide compensation for induced voltages, including

those attributable to asymmetry in the volumetric density of the lightning or other

transient current, canceling out the spurious voltages and measuring the true voltage across the component.

This work was done by Carlos T. Mata of

Dynacs, Inc., for Kennedy Space Center.

For further information, contact the Kennedy

Innovative Partnerships Office at (321)

867-8130.

KSC-12381/448

High-Performance Satellite/Terrestrial-Network Gateway

This apparatus affords flexibility in the choice of data rates.

Lyndon B. Johnson Space Center, Houston, Texas

A gateway has been developed to enable digital communication between (1)

the high-rate receiving equipment at

NASA’s White Sands complex and (2) a

standard terrestrial digital communication network at data rates up to 622

Mb/s. The design of this gateway can

also be adapted for use in commercial

Earth/satellite and digital communication networks, and in terrestrial digital

communication networks that include

wireless subnetworks.

“Gateway” as used here signifies an

electronic circuit that serves as an interface between two electronic communication networks so that a computer (or

other terminal) on one network can

communicate with a terminal on the

other network. The connection between this gateway and the high-rate receiving equipment is made via a synchronous serial data interface at the

emitter-coupled-logic (ECL) level. The

connection between this gateway and a

standard asynchronous transfer mode

(ATM) terrestrial communication network is made via a standard user network interface with a synchronous optical network (SONET) connector. The

gateway contains circuitry that performs the conversion between the ECL

and SONET interfaces. The data rate of

the SONET interface can be either

155.52 or 622.08 Mb/s. The gateway derives its clock signal from a satellite

modem in the high-rate receiving

equipment and, hence, is agile in the

sense that it adapts to the data rate of

the serial interface.

Although the ECL interface is synchronous, it bears ATM cells (in effect, data packets for asynchronous

transmission) according to Telecommunications Industry Association

(TIA) Standard 787. This characteristic renders the gateway transparent to

any protocols above ATM, including

the Internet Protocol (IP), the User

Datagram Protocol (UDP), and the

Transmission Control Protocol (TCP).

The gateway can perform ReedSolomon encoding for forward error

correction (FEC) during operation

with a satellite source that is not

equipped for FEC.

The primary advantage afforded by

this gateway is that it enables a satellite/Earth network or the wireless subnetwork of a terrestrial network to operate at a data rate independent of that of

the network components at either end

of a data-communication link. Because

terrestrial networks must subscribe to

stratified, standard data rates, the data

rates of the terminals of the networks

often limit the performances of the wireless links. Often, the optimal data rate

for a wireless link in a terrestrial network

lies between the standard data rates supported by the remainder of the network.

A gateway like this one would enable a

wireless portion of a terrestrial network

segment to operate at its optimal data

rate, while preserving the standardization of data rates at the network terminals.

This work was done by David R. Beering of

Infinite Global Infrastructures, LLC, for

Johnson 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:

Infinite Global Infrastructures, LLC

480 E. Roosevelt Rd. STE 205

West Chicago, IL 60185

E-mail: drbeering@igillc.com

Refer to MSC-23316, volume and number

of this NASA Tech Briefs issue, and the

page number.
10 NASA Tech Briefs, August 2005

The Internet Voice Distribution System (IVoDS) is a voice-communication

system that comprises mainly computer

hardware and software. The IVoDS was

developed to supplement and eventually

replace the Enhanced Voice Distribution System (EVoDS), which, heretofore, has constituted the terrestrial subsystem of a system for voice communications among crewmembers of the International Space Station (ISS), workers at

the Payloads Operations Center at Marshall Space Flight Center, principal investigators at diverse locations who are

responsible for specific payloads, and

others. The IVoDS utilizes a communication infrastructure of NASA and NASArelated intranets in addition to, as its

name suggests, the Internet. Whereas

the EVoDS utilizes traditional circuitswitched telephony, the IVoDS is a

packet-data system that utilizes a voice

over Internet protocol (VOIP). Relative

to the EVoDS, the IVoDS offers advantages of greater flexibility and lower cost

for expansion and reconfiguration.

The IVoDS is an extended version of

a commercial Internet-based voice conferencing system that enables each user

to participate in only one conference at

a time. In the IVoDS, a user can receive

audio from as many as eight conferences simultaneously while sending

audio to one of them. The IVoDS also

incorporates administrative controls,

beyond those of the commercial system, that provide greater security and

control of the capabilities and authorizations for talking and listening afforded to each user.

The IVoDS has a client/ server architecture. It utilizes the H.323 VOIP with

custom extensions as required to support operations unique to the ISS mission. An authorized user can gain access

to the IVoDS by means of a standard

desktop personal computer and modem

capable of intranet or Internet communication with the Payload Operations

Center at a rate of at least 128 kb/s. The

subsystems of the IVoDS (see figure) include the following:

• Conference or voice servers: These are

computers that host conferences (voice

loops) to which client computers connect.

• Conference or voice clients: These are the

aforementioned client computers, which

are located at the remote work sites of individual users.

• Administrator server: This is a computer that processes requests from the

administrator client described below.

Internet-Based System for Voice Communication With the ISS

This system offers advantages over a prior telephony-based system.

Marshall Space Flight Center, Alabama

Conference

Servers

Internet and

Research &

Education

Networks

Administrator

Server

PAYCOM

Client

Administrator

Client

VPN

Server

IVoDS

Conference

Telephone Clients

Gateways EVoDS

Johnson

Space Center

EVoDS

Voice

Panel

International Space Station (ISS)

Payload Operations Integration Center at

Marshall Space Flight Center

ISS/Ground Voice

Communications

The IVoDS manages voice communications among users aboard the ISS and users at diverse terrestrial locations.
NASA Tech Briefs, August 2005 11

This computer maintains collections of

network, user, and conference data,

and controls the conference or voice

servers.

• Administrator client: This computer

manages users, conferences, and the

database in the administrator server.

• Payload communications manager

(PAYCOM) client: This is a computer

that exerts control over who talks in

such restricted conferences as those

that include direct communication

with crewmembers of the ISS.

• Virtual public network (VPN) server:

Like other VPN servers, this serves to

authenticate, by use of identification

numbers and encryption, the computers of remote users (in this case, conference clients) who seek access to the

IVoDS.

• Telephony gateways: These are interfaces

between (1) the EVoDS voice loops,

which are of public switched telephone

network type, and (2) the IVoDS InternetProtocol-based conferences.

This work was done by James Chamberlain, Gerry Myers, David Clem, and Terri

Speir of AZ Technology, Inc., for Marshall

Space Flight Center. For further information, contact Caroline Wang, MSFC Software

Release Authority, at (256) 544-3887 or 

Caroline.K.Wang@nasa.gov. Refer to MFS31666.

A stripline-to-microstrip transition has

been incorporated into a multilayer circuit

board that supports a distributed solid-state

microwave power amplifier, for the purpose of coupling the microwave signal from

a buried-layer stripline to a top-layer microstrip. The design of the transition could be

adapted to multilayer circuit boards in such

products as cellular telephones (for connecting between circuit-board signal lines

and antennas), transmitters for Earth/satellite communication systems, and computer

mother boards (if processor speeds increase

into the range of tens of gigahertz).

The transition is designed to satisfy the

following requirements in addition to the

basic coupling requirement described

above:

• The transition must traverse multiple

layers, including intermediate layers

that contain DC circuitry.

• The transition must work at a frequency of 32 GHz with low loss and low

reflection.

• The power delivered by the transition

to top-layer microstrip must be split

equally in opposite directions along the

microstrip. Referring to the figure, this

amounts to a requirement that when

power is supplied to input port 1, equal

amounts of power flow through output

ports 2 and 3.

• The signal-line via that is necessarily a

part of such a transition must not be

what is known in the art as a blind via;

that is, it must span the entire thickness

of the circuit board.

The lower end of the via is connected

to a circular pad on the bottom

(ground) layer. Electrically, this pad is a

dead-end or no-connection point. The

pad is surrounded by a cutout in the

ground layer; the cutout includes a recStripline/Microstrip Transition in Multilayer Circuit Board

Transitions like this one could be useful in microwave communication products.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Built Into a Multilayer Circuit Board, the stripline-to-microstrip transition couples power from port 1

to ports 2 and 3.

Signal Via

(Spans Entire Thickness of

Circuit Board)

Port 2

Port 3

Port 3

Port 2

Microstrip on

Top Layer

Mode-Strapping

Vias

Cutout in

Ground Layer

Microstrip in

Top Layer

ENLARGED TOP VIEW

Ground

Plane

Step-Matching

Sections on Buried

Stripline (inner layer)

Signal-Line

Via

Port 1
12 NASA Tech Briefs, August 2005

Dual-Band Feed for a Microwave Reflector Antenna

Two coaxial waveguides carry radiation in two frequency bands.

NASA’s Jet Propulsion Laboratory, Pasadena, California

A waveguide feed has

been designed to provide

specified illumination

patterns for a dual-reflector antenna in two wavelength bands: 8 to 9 GHz

and 30 to 40 GHz. The

feed (see figure) has a

coaxial configuration: A

wider circular tube surrounds a narrower circular tube that serves as a

waveguide for the signals

in the 30-to-40-GHz band.

The annular space between the narrower and

the wider tube serves as a

coaxial waveguide for the

signals in the 8-to-9-GHz band. The

nominal design frequencies of the outer

and inner waveguides are 8.45 and 32

GHz, respectively.

Each of the two waveguides is terminated in a component that is sized and

shaped to help focus the radiation in

its respective frequency band into the

specified illumination pattern. For the

outer waveguide, the beam-shaping termination is a corrugated horn; for the

inner waveguide, the beam-shaping termination is a dielectric rod insert.

This work was done by Daniel Hoppe and

Harry Reilly of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

NPO-40418

A Corrugated Horn and a Dielectric Rod Insert help to shape the

beams radiated from the ends of the outer and inner waveguide,

respectively.

Dielectric

Insert

Corrugated

Horn

Outer

Tube

Inner

Tube

Outer Waveguide in

Annular Space

Between Tubes

(for 8 to 9 GHz)

Inner Waveguide in

Inner Tube

(for 30 to 40 GHz)

Foam 

Support

tangular main portion that ends in a triangular taper at the input end.

The cutout lies above a standard rectangular cavity. The combination of the

triangular-taper portion of the cutout

and the rectangular cavity serves to

focus the electromagnetic field to propagate up the signal-line via. The cavity

also prevents coupling of the signal to

neighboring circuits. The rectangular

cavity can be fabricated easily by conventional machining techniques; the triangular-taper portion of the cutout is

fabricated easily by printed-circuit techniques. To compensate for reflections

from the transition, step-matching sections are included in the vicinity of the

triangular taper.

Mode-strapping vias are also included. These vias are blind; that is, they

terminate at, and are connected to, an

intermediate layer. These vias can be

blind because they do not carry the signal. These can be closely spaced. The

closeness of the spacing compensates

somewhat for the unreliability of connections formed in the process of fabrication of blind vias.

This work was done by Larry Epp and

Abdur Khan of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

NPO-41061
NASA Tech Briefs, August 2005 13

Software

Quadratic Programming for

Allocating Control Effort

A computer program calculates an optimal allocation of control effort in a system

that includes redundant control actuators.

The program implements an iterative (but

otherwise single-stage) algorithm of the

quadratic-programming type. In general,

in the quadratic-programming problem,

one seeks the values of a set of variables

that minimize a quadratic cost function,

subject to a set of linear equality and inequality constraints. In this program, the

cost function combines control effort (typically quantified in terms of energy or fuel

consumed) and control residuals (differences between commanded and sensed

values of variables to be controlled). In

comparison with prior control-allocation

software, this program offers approximately equal accuracy but much greater

computational efficiency. In addition, this

program offers flexibility, robustness to actuation failures, and a capability for selective enforcement of control requirements.

The computational efficiency of this program makes it suitable for such complex,

real-time applications as controlling redundant aircraft actuators or redundant

spacecraft thrusters. The program is written in the C language for execution in a

UNIX operating system.

This program was written by Gurkirpal

Singh of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained in a TSP (see page 1).

This software used in this innovation is

available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (818) 393-2827. Refer to

NPO-40592.

Range Process Simulation

Tool

Range Process Simulation Tool

(RPST) is a computer program that assists managers in rapidly predicting and

quantitatively assessing the operational

effects of proposed technological additions to, and/or upgrades of, complex

facilities and engineering systems such

as the Eastern Test Range. Originally designed for application to space transportation systems, RPST is also suitable

for assessing effects of proposed changes

in industrial facilities and large organizations. RPST follows a model-based approach that includes finite-capacity

schedule analysis and discrete-event

process simulation. A component-based,

scalable, open architecture makes RPST

easily and rapidly tailorable for diverse

applications. Specific RPST functions

include: (1) definition of analysis objectives and performance metrics; (2) selection of process templates from a processtemplate library; (3) configuration of

process models for detailed simulation

and schedule analysis; (4) design of operations-analysis experiments; (5) schedule and simulation-based process analysis; and (6) optimization of performance

by use of genetic algorithms and simulated annealing. The main benefits afforded by RPST are provision of information that can be used to reduce costs

of operation and maintenance, and the

capability for affordable, accurate, and

reliable prediction and exploration of

the consequences of many alternative

proposed decisions.

This program was written by Dave Phillips,

William Haas, and Tim Barth of Kennedy

Space Center, and Perakath Benjamin,

Michael Graul, and Olga Bagatourova of

Knowledge Based Systems.

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:

Perakath Benjamin

Knowledge Based Systems

4710 St. Andrews Drive

College Station, TX 77845

Phone: (979) 260-5279

E-mail: Pbenjamin@kbsi.com

Refer to KSC-12511, volume and number

of this NASA Tech Briefs issue, and the

page number. 

Simulator of Space Communication Networks

Multimission Advanced Communications Hybrid Environment for Test and

Evaluation (MACHETE) is a suite of software tools that simulates the behaviors of

communication networks to be used in

space exploration, and predict the performance of established and emerging

space communication protocols and

services. MACHETE consists of four general software systems: (1) a system for

kinematic modeling of planetary and

spacecraft motions; (2) a system for characterizing the engineering impact on the

bandwidth and reliability of deep-space

and in-situ communication links; (3) a

system for generating traffic loads and

modeling of protocol behaviors and state

machines; and (4) a system of user-interface for performance metric visualizations. The kinematic-modeling system

makes it possible to characterize space

link connectivity effects, including occultations and signal losses arising from dynamic slant-range changes and antenna

radiation patterns. The link-engineering

system also accounts for antenna radiation patterns and other phenomena, including modulations, data rates, coding,

noise, and multipath fading. The protocol system utilizes information from the

kinematic-modeling and link-engineering systems to simulate operational scenarios of space missions and evaluate

overall network performance. In addition, a Communications Effect Server

(CES) interface for MACHETE has been

developed to facilitate hybrid simulation

of space communication networks with

actual flight/ground software/hardware

embedded in the overall system.

This work was done by Loren Clare, Esther

Jennings, Jay Gao, John Segui, and Winston

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

contained in a TSP (see page 1).

This software used in this innovation is

available for commercial licensing. Please

contact Karina Edmonds of the California

Institute of Technology at (818) 393-2827.

Refer to NPO-41373.

Computing Q-D Relationships for Storage 

of Rocket Fuels

The Quantity Distance Measurement

Tool is a GIS BASEP computer program

that aids safety engineers by calculating

quantity-distance (Q-D) relationships

for vessels that contain explosive chemicals used in testing rocket engines. (Q-D

relationships are standard relationships

between specified quantities of specified

explosive materials and minimum distances by which they must be separated

from persons, objects, and other explosives to obtain specified types and degrees of protection.) The program uses

customized geographic-information-system (GIS) software and calculates Q-D

relationships in accordance with NASA’s

Safety Standard For Explosives, Propel-
14 NASA Tech Briefs, August 2005

lants, and Pyrotechnics. Displays generated by the program enable the identification of hazards, showing the relationships of propellant-storage-vessel safety

buffers to inhabited facilities and public

roads. Current Q-D information is calculated and maintained in graphical form

for all vessels that contain propellants or

other chemicals, the explosiveness of

which is expressed in TNT equivalents

[amounts of trinitrotoluene (TNT) having equivalent explosive effects]. The

program is useful in the acquisition, siting, construction, and/or modification

of storage vessels and other facilities in

the development of an improved test-facility safety program.

This program was written by Keith Jester of

General Dynamics for Stennis Space Center.

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

to the Intellectual Property Manager, Stennis

Space Center, (228) 688-1929. Refer to

SSC-00209.

Contour Error Map 

Algorithm

The contour error map (CEM) algorithm and the software that implements

the algorithm are means of quantifying

correlations between sets of time-varying data that are binarized and registered on spatial grids. The present version of the software is intended for use

in evaluating numerical weather forecasts against observational sea-breeze

data. In cases in which observational

data come from off-grid stations, it is

necessary to preprocess the observational data to transform them into gridded data. First, the wind direction is

gridded and binarized so that D(i,j;n) is

the input to CEM based on forecast

data and d(i,j;n) is the input to CEM

based on gridded observational data.

Here, i and j are spatial indices representing 1.25-km intervals along the

west-to-east and south-to-north directions, respectively; and n is a time index

representing 5-minute intervals. A binary value of D or d = 0 corresponds to

an offshore wind, whereas a value of D

or d = 1 corresponds to an onshore

wind. CEM includes two notable subalgorithms: One identifies and verifies

sea-breeze boundaries; the other, which

can be invoked optionally, performs an

image-erosion function for the purpose

of attempting to eliminate river-breeze

contributions in the wind fields.

This work was done by Francis Merceret of

Kennedy Space Center; John Lane and

Christopher Immer of Dynacs, Inc.; and

Jonathan Case and John Manobianco of

ENSCO, Inc. For further information, contact

the Kennedy Innovative Partnerships Office at

(321) 867-8130.

KSC-12489

Portfolio Analysis Tool

Portfolio Analysis Tool (PAT) is a Webbased, client/server computer program

that helps managers of multiple projects

funded by different customers to make

decisions regarding investments in those

projects. PAT facilitates analysis on a

macroscopic level, without distraction by

parochial concerns or tactical details of

individual projects, so that managers’

decisions can reflect the broad strategy

of their organization. PAT is accessible

via almost any Web-browser software. Experts in specific projects can contribute

to a broad database that managers can

use in analyzing the costs and benefits of

all projects, but do not have access for

modifying criteria for analyzing projects:

access for modifying criteria is limited to

managers according to levels of administrative privilege. PAT affords flexibility

for modifying criteria for particular

“focus areas” so as to enable standardization of criteria among similar projects,

thereby making it possible to improve assessments without need to rewrite computer code or to rehire experts, and

thereby further reducing the cost of

maintaining and upgrading computer

code. Information in the PAT database

and results of PAT analyses can be incorporated into a variety of ready-made or

customizable tabular or graphical displays.

This program was written by Tim Barth

and Edgar Zapata of Kennedy Space Center, and Perakath Benjamin, Mike Graul, and

Doug Jones of KBSI, Inc.

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:

Perakath Benjamin

Knowledge Based Systems, Inc.

1408 University Drive East

College Station, TX 77840

Phone: (979) 260-5274

Refer to KSC-12510, volume and number

of this NASA Tech Briefs issue, and the

page number.
NASA Tech Briefs, August 2005 15

Materials

Anhydrous Proton-Conducting Membranes for Fuel Cells

Operating temperatures could be as high as 200 °C.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Polymeric electrolyte membranes that

do not depend on water for conduction of

protons are undergoing development for

use in fuel cells. Prior polymeric electrolyte

fuel-cell membranes (e.g., those that contain perfluorosulfonic acid) depend on

water and must be limited to operation

below a temperature of 125 °C because

they retain water poorly at higher temperatures. In contrast, the present developmental anhydrous membranes are expected to

function well at temperatures up to 200 °C.

The developmental membranes exploit a hopping-and-reorganization proton-conduction process that can occur in

the solid state in organic amine salts and

is similar to a proton-conduction process

in a liquid. This process was studied during the 1970s, but until now, there has

been no report of exploiting organic

amine salts for proton conduction in fuel

cells.

The present development work exploits

and extends the previous research on

water-free proton conduction in organic

amine salts. This work has included an investigation of acid salts of triethylenediamine in which each molecule contains

two tertiary nitrogen atoms that can be

quaternized. It has been demonstrated

that by combining such a proton conductor with nanoparticles of suitable oxide

(for example, silica) and a stable binder

[for example, poly(tetrafluoroethylene)],

one can fabricate a polymeric electrolyte

membrane inexpensively. The figure depicts the results of measurements of the

ionic conductivity of such a membrane

made from triethylenediamine sulfate.

The activation energy for proton transport, obtained from the slope of the plot,

lies in the range of 0.15 to 0.20 eV — a low

range indicative of facile transport of protons.

Proton-conducting membranes to be

investigated in the continuing development effort are divided into the following three classes according to the amine

salts and related compounds on which

they are based:

Type I: Organic tertiary amine bisulfates,

triflates (trifluoromethanesulfomates),

and hydrogen phosphates.

Type II: Polymeric quaternized amine

bisulfates, triflates, and hydrogen phosphates.

Type III: Polymeric quaternized bisulfates, hydrogen phosphates, and triflates combined with perfluorosulfonic

acid-based polymers.

As in the case of the membrane described in the preceding paragraph, a proton-conducting membrane of type I would

0

–6

–5

–4

–3

–2

–1

0.5 1.0 1.5 2.0

190 °C

140 °C

1,000/(Temperature in Kelvins)

Log (Conductivity 

Ω–1cm–1)

2.5 3.0 3.5 4.0

The Ionic Conductivity of a triethylenediamine sulfate membrane was measured as a function of temperature. The conductivity vales are here plotted on a logarithmic scale versus reciprocal of temperature

data — a form of plot that facilitates the estimation of activation energy.

Glass Frit Filters for Collecting Metal Oxide Nanoparticles

Lyndon B. Johnson Space Center, Houston, Texas

Filter disks made of glass frit have

been found to be effective as means of

high-throughput collection of metal

oxide particles, ranging in size from a

few to a few hundred nanometers, produced in gas-phase condensation reactors. In a typical application, a filter is

placed downstream of the reactor and a

valve is used to regulate the flow of reactor exhaust through the filter. The

exhaust stream includes a carrier gas,

particles, byproducts, and unreacted

particle-precursor gas. The filter selectively traps the particles while allowing

the carrier gas, the byproducts, and, in

some cases, the unreacted precursor, to

flow through unaffected. Although the

pores in the filters are much larger

than the particles, the particles are nevertheless trapped to a high degree:

Anecdotal information from an experiment indicates that 6-nm-diameter particles of MnO2 were trapped with >99-

percent effectiveness by a filtering

device comprising a glass-frit disk having pores 70 to 100 μm wide immobilized in an 8-cm-diameter glass tube

equipped with a simple twist valve at its

downstream end.

This work was done by John Ackerman,

Dan Buttry, Geoffrey Irvine, and John Pope

of Blue Sky Batteries, Inc., for Johnson

Space Center. For further information, contact the Johnson Innovative Partnerships Office at (281) 483-3809.

MSC-23425
16 NASA Tech Briefs, August 2005

be fabricated from one or more salts of

type I by processing a mixture of fine salt

particles, oxide nanoparticles, and

poly(tetrafluoroethylene).

Fabrication of membranes of type II

would involve synthesis of polymers, followed by casting of the polymers into

membranes. Depending on the starting ingredients and process used to make a given

membrane, either the quaternized nitrogen atoms would automatically be incorporated into the membrane during polymerization, or else it would be necessary to

quaternize the membrane in a bisulfate or

a hydrogen phosphate.

A membrane of type III would be a twocomponent polymeric system cast from a

solution containing a perfluorosulfonic

acid-based polymer and a quaternary-nitrogen-containing polymer salt of type II. This

polymer would make it possible to exploit

the strong acidity of the dry perfluorosulfonic acid and the flexibility of its polymer

back bone. The general objective in formulating such a two-component system is to increase the number of sites available for proton hopping and provide for additional

relaxation and reorganization mechanisms

in order to reduce the heights of barrier to

the transport of protons.

This work was done by Sekharipuram

Narayanan and Shiao-Pin S. Yen of Caltech for NASA’s Jet Propulsion Laboratory. For further information, access the

Technical Support Package (TSP) free online at www.techbriefs.com/tsp under the

Materials category.

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

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-30493, volume and number

of this NASA Tech Briefs issue, and the

page number.
A portable electron-beam free-form

fabrication (EB F3

) system, now undergoing development, is intended to afford a capability for manufacturing

metal parts in nearly net sizes and

shapes. Although the development effort is oriented toward the eventual

use of systems like this one to supply

spare metal parts aboard spacecraft in

flight, the basic system design could

also be adapted to terrestrial applications in which there are requirements

to supply spare parts on demand at locations remote from warehouses and

conventional manufacturing facilities.

Prior systems that have been considered for satisfying the same requirements (including prior free-form fabrication systems) are not easily portable

because of their bulk and massive size.

The mechanical properties of the components that such systems produce are

often inferior to the mechanical properties of the corresponding original,

conventionally fabricated components.

In addition, the prior systems are not

efficient in the utilization of energy

and of feedstock. In contrast, the present developmental system is designed

to be sufficiently compact and lightweight to be easily portable, to utilize

both energy and material more efficiently, and to produce components

that have mechanical properties approximating those of the corresponding original components.

The developmental EB F3 system will

include a vacuum chamber and associated vacuum pumps, an electron-beam

gun and an associated power supply, a

multiaxis positioning subsystem, a precise wire feeder, and an instrumentation system for monitoring and control. The electron-beam gun,

positioning subsystem, and wire feeder

will be located inside the vacuum

chamber (see figure). The electronbeam gun and the wire feeder will be

mounted in fixed positions inside the

domed upper portion of the vacuum

chamber. The positioning subsystem

and ports for the vacuum pumps will

be located on a base that could be

dropped down to provide full access to

the interior of the chamber when not

under vacuum.

During operation, wire will be fed to

a fixed location, entering the melted

pool created by the electron beam.

Heated by the electron beam, the wire

will melt and fuse to either the substrate or with the previously deposited

metal wire fused on top of the positioning table. Based on a computer aided

design (CAD) model and controlled by

a computer, the positioning subsystem

NASA Tech Briefs, August 2005 17

Vacuum Chamber

Wire Feeder

Wire

Electron-Beam Gun

Substrate

4-Axis Positioning

Subsystem

ARTIST'S CONCEPTION OF VACUUM CHAMBER AND EQUIPMENT WITHIN

Control/Data System

(Laptop Computer)

Electron-Beam

Power Supply

Wire

Feeder

Electron- Beam Gun

Workpie Workpiece

a

z

y

x

Vacuum Chamber

Structural Frame

SCHEMATIC DIAGRAM OF SYSTEM

–

+

Vent

(Rotation about an

axis in the x-y plane.)

Legend:

Pressure

Sensor

High-Vacuum Pump

Roughing Pump

Valve

High Current/High Voltage Power

115 V, 60 Hz AC

Command Signals

Data Signals

Portable Electron-Beam Free-Form Fabrication System

The electron beam in this system will be of relatively low voltage.

Lyndon B. Johnson Space Center, Houston, Texas

A Metal Workpiece Will Be Formed by using an electron beam to melt feed wire over a substrate that

will be moved by a four-axis positioning subsystem.

Manufacturing
18 NASA Tech Briefs, August 2005

will move the substrate so that the

metal deposited from the wire will accumulate to form a component of the

desired size and shape.

Whereas conventional electron-beam

welding systems generally utilize electron-accelerating potentials of the order

of 60 kV, the proposed system will utilize

a potential between 8 and 15 kV. Consequently, the shielding needed to protect

personnel and equipment against x rays

generated by impingement of the electrons on the workpiece can be considerably less massive. The electron beam will

deliver a maximum power between 3

and 5 kW and be focused to heat a small

spot. Because a considerably higher fraction of an electron beam’s energy is converted into heat (relative to a laser

beam, for example) in a small spot on

the workpiece, the use of the electron

beam will contribute to the energy efficiency of the system. The use of the precise wire feeder will enable efficient utilization of feedstock. The operational

parameters will be selected to ensure the

proper feeding, melting, and consolidation of the feedstock to yield a deposit

that will be nearly 100 percent dense

(that is, will contain little or no porosity)

and will have a very fine grain structure,

as needed to ensure superior mechanical properties.

This work was performed by J. Kevin

Watson and Daniel D. Petersen of Johnson

Space Center, and Karen M. Taminger

and Robert A. Hafley of Langley Research

Center. For further information, contact the

Johnson Innovative Partnerships Office at

(281) 483-3809.

MSC-23518
NASA Tech Briefs, August 2005 19

Bio-Medical

Miniature Laboratory for Detecting Sparse Biomolecules

Specimens would be concentrated and sorted before detection.

NASA’s Jet Propulsion Laboratory, Pasadena, California

The figure schematically depicts a

miniature laboratory system that has

been proposed for use in the field to

detect sparsely distributed biomolecules. By emphasizing concentration

and sorting of specimens prior to detection, the underlying system concept

would make it possible to attain high

detection sensitivities without the need

to develop ever more sensitive biosensors. The original purpose of the proposal is to aid the search for signs of life

on a remote planet by enabling the detection of specimens as sparse as a few

molecules or microbes in a large

amount of soil, dust, rocks, water/ice,

or other raw sample material. Some version of the system could prove useful on

Earth for remote sensing of biological

contamination, including agents of biological warfare.

Processing in this system would begin

with dissolution of the raw sample material in a sample-separation vessel. The solution in the vessel would contain floating microscopic magnetic beads coated

with substances that could engage in

chemical reactions with various target

functional groups that are parts of target

molecules. The chemical reactions

would cause the targeted molecules to be

captured on the surfaces of the beads.

By use of a controlled magnetic

field, the beads would be concentrated

in a specified location in the vessel.

Once the beads were thus concentrated, the rest of the solution would

be discarded. This procedure would

obviate the filtration steps and thereby

also eliminate the filter-clogging difficulties of typical prior sample-concentration schemes. For ferrous dust/soil

samples, the dissolution would be

done first in a separate vessel before

the solution is transferred to the microbead-containing vessel.

A small amount of a solvent solution

would be used to elute the captured

target molecules from the surfaces of

the beads. The resulting solution

would be made to flow through a seRaw Sample Material Input

SAMPLE SEPARATION AND ENRICHING 

OPTICAL DETECTION OF TARGET MOLECULES

Capillary

Flow Pump

Planar Capillary 

Serial Array

Ultraviolet Lamp

Detector Array 

Filters/Grating

Sample-Separation

Vessel Containing

Floating Coated

Magnetic Beads

Electromagnet

Agitator

Drive

Process of Target Molecule Separation

A B C D

N S

Discharge 

Outlet

Raw Sample Material Would Be Processed to concentrate and sort specimens (specifically, target molecules), which would then be detected by optical or

other means.
20 NASA Tech Briefs, August 2005

ries of capillary detection channels,

which would be coated with probe

molecules, each designed to capture a

specific functional group. Once the

flow had run its course, an instrument

yet to be developed (perhaps an integrated optical spectrometer) would be

used to detect and analyze molecules

of interest that had accumulated in

the channels. The outputs of the instrument would be used to construct a

matrix of data from which the concentrations of the target molecules would

be estimated.

This work was done by Ying Lin and Nan

Yu of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained in a TSP (see page 1). NPO-40281

Multicompartment Liquid-Cooling/Warming Protective

Garments

Lyndon B. Johnson Space Center, Houston, Texas

Shortened, multicompartment liquidcooling/warming garments (LCWGs)

for protecting astronauts, firefighters,

and others at risk of exposure to extremes of temperature are undergoing

development. Unlike prior liquid-circulation thermal-protection suits that

provide either cooling or warming but

not both, an LCWG as envisioned

would provide cooling at some body locations and/or heating at other locations, as needed: For example, sometimes there is a need to cool the body

core and to heat the extremities simultaneously. An LCWG garment of the

type to be developed is said to be shortened because the liquid-cooling and -

heating zones would not cover the

whole body and, instead, would cover

reduced areas selected for maximum

heating and cooling effectiveness.

Physiological research is under way to

provide a rational basis for selection of

the liquid-cooling and -heating areas.

In addition to enabling better (relative

to prior liquid-circulation garments)

balancing of heat among different

body regions, the use of selective heating and cooling in zones would contribute to a reduction in the amount of

energy needed to operate a thermalprotection suit.

This work was done by Victor S. Koscheyev,

Gloria R. Leon, and Michael J. Dancisak of

the University of Minnesota for Johnson

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:

University of Minnesota

Patents and Technology Marketing

Attn: Beth Trend, B.S.E.E., Director

Biological, Engineering and Computer

Technologies

450 McNamara Alumni Center

200 Oak Street S.E.

Minneapolis, MN 55455-2070

Phone: (612) 626-9293

Fax: (612) 624-6554

E-mail: btrend@umn.edu

Refer to MSC-23305, volume and number

of this NASA Tech Briefs issue, and the

page number.
Laser gauges have been developed to

satisfy requirements specific to monitoring the amplitude of the motion of an

optical-path-length modulator that is

part of an astronomical interferometer.

The modulator includes a corner-cube

retroreflector driven by an electromagnetic actuator. During operation of the

astronomical interferometer, the electromagnet is excited to produce linear reciprocating motion of the corner-cube

retroreflector at an amplitude of 2 to 4

mm at a frequency of 250, 750, or 1,250

Hz. Attached to the corner-cube retroreflector is a small pick-off mirror. To suppress vibrations, a counterweight having

a mass equal to that of the corner-cube

retroreflector and pick-off mirror is

mounted on another electromagnetic actuator that is excited in opposite phase.

Each gauge is required to measure the

amplitude of the motion of the pick-off

mirror, assuming that the motions of the

pick-off mirror and the corner-cube

retroreflector are identical, so as to measure the amplitude of motion of the corner-cube retroreflector to within an

error of the order of picometers at each

excitation frequency.

Each gauge is a polarization-insensitive heterodyne interferometer that includes matched collimators, beam separators, and photodiodes (see figure).

The light needed for operation of the

gauge comprises two pairs of laser

beams, the beams in each pair being

separated by a beat frequency of 80 kHz.

The laser beams are generated by an apparatus, denoted the heterodyne plate,

that includes stabilized helium-neon

lasers, acousto-optical modulators, and

associated optical and electronic subsystems. The laser beams are coupled from

the heterodyne plate to the collimators

via optical fibers.

The basic heterodyne-interferometer architecture is not new, but prior

systems based on the architecture

have not afforded accuracies as great

as those of the present gauges. The

novelty of the present gauges lies in

numerous details of design, construction, and setup that, taken together,

make it possible to obtain the required level of accuracy. Within the

limited space available for this article,

it is possible only to summarize a few

major details:

• The gauge utilizes an inner beam pair

in one of the interferometer arms (the

probe arm) and an outer beam pair in

the other interferometer arm (the reference arm). The beams are separated

by (1) an inner mask and a mirror with

a hole in the reference arm, and (2) an

outer mask in the probe arm. Care is

taken to provide a small radial separation between the beams to minimize

leakage between them. 

• In the design, construction, and setup of

the collimators, great care is taken to

eliminate scattered light, to adjust the

collimator lenses to the collimating positions, and to match the collimator outputs. Although the wave fronts coming

out of the collimators are not very flat,

they are matched to within a fraction of

the 633-nm laser wavelength. Once the

collimators are adjusted to the required

match, they are permanently glued in

position.

• The photodetectors, and lenses that

focus light on the photodetectors, are

mounted in receiver assemblies, the optical configuration of which is the inverse

of that of the collimators. The photodiodes are only 100 mm in diameter and

are mounted at the precise focal points

of the lenses. The precise placement and

the smallness of the photodiodes helps

to discriminate against leakage in the

form of diffracted light, which travels at

slight angles to the optical axes of the

main masked beams.

Two of the gauges have been built and

have been demonstrated to be capable of

a sensitivity of ≤3 pm/Hz1/2 within 1-Hzwide bands at each of 250, 750, and 1,250

Hz. When the gauges were tested while

monitoring the same optical-path-length

modulator, the root-mean-square systematic error per gauge was found to be

about 25 pm. However, the systematic errors do not constitute a major drawback,

inasmuch as they can be reduced by cyclic

averaging and they occur at a frequency

above 1,250 Hz.

This work was done by Yekta Gursel of Caltech for NASA’s Jet Propulsion Laboratory.

Further information is contained in a TSP

(see page 1).

NPO-30799

NASA Tech Briefs, August 2005 21

Physical Sciences

Photodiode 

Outputs to 

Processing Circuits

Inner Mask

Outer Mask Probe

Photodiode

Reference

Photodiode

Beam Dump

Beam

Splitters

Reference

Mirror

Pick-off Mirror 

on Retroreflector 

on Modulator

Receiver

Assembly

Receiver Assembly Lenses

Matched

Collimators

Optical Fibers Carrying Laser

Beams From Heterodyne Plate

Lens

Lens

Laser Metrology for an Optical-Path-Length Modulator

Sensitivity is of the order of picometers.

NASA’s Jet Propulsion Laboratory, Pasadena, California

This Laser Heterodyne Interferometer utilizes an inner probe beam pair and an outer reference beam

pair. High sensitivity and high accuracy are achieved through innovative design features and careful

attention to detail in construction and alignment.
22 NASA Tech Briefs, August 2005

PCM Passive Cooling System Containing Active Subsystems

A PCM would absorb intense heat bursts and would be regenerated between them. 

Lyndon B. Johnson Space Center, Houston, Texas

A multistage system has been proposed

for cooling a circulating fluid that is subject to intermittent intense heating. The

system would be both flexible and redundant in that it could operate in a basic

passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a

second cooling subsystem that could be

active, passive, or a combination of both.

This flexibility and redundancy, in combination with the passive nature of at least

one of the modes of operation, would

make the system more reliable, relative to

a conventional cooling system.

The system would include a tube-inshell heat exchanger, within which the

space between the tubes would be filled

with a phase-change material (PCM). The

circulating hot fluid would flow along the

tubes in the heat exchanger. In the basic

passive mode of operation, heat would be

conducted from the hot fluid into the

PCM, wherein the heat would be stored

temporarily by virtue of the phase change.

Of course, it would become necessary

to remove heat from the PCM to maintain or restore its heat-absorption capacity. This would be accomplished by means

of the first, active cooling subsystem,

which would circulate a cooling fluid

through one or more tube(s) in thermal

contact with the PCM. For example, such

a cooling tube could be wrapped in a spiral around the heat-exchanger shell as

shown in the figure.

The heat exchanger would include an

inner core that would accommodate the

second cooling subsystem. As mentioned above, the second cooling subsystem could be active, passive, or both.

This subsystem would remove heat from

the core by means of heat pipes, a water

membrane evaporator, and/or one or

more active refrigeration devices. In the

case of a water membrane evaporator,

heat would be dissipated in the environment by releasing the steam generated

at the membrane.

This work was done by David E. Blanding

and David I. Bass of the Boeing Co. for Johnson

Space Center. For further information, contact

the Johnson Innovative Partnerships Office at

(281) 483-3809.

MSC-23652

Hot

Fluid In

Cool

Fluid Out

Cool

Fluid Out

Hot

Fluid In

Spiral-Wrapped Tube of

First Cooling Subsystem

Core Containing Second

 Cooling Subsystem

Phase-Change

Material

This Cross Section Is Greatly Simplified to show only selected major features of a heat exchanger according to the proposal.

Automated Electrostatics Environmental Chamber

Atmospheric temperature and pressure can be varied between the extremes of Mars and Earth.

John F. Kennedy Space Center, Florida

The Mars Electrostatics Chamber

(MEC) is an environmental chamber designed primarily to create atmospheric

conditions like those at the surface of

Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a

vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing

and analysis system, and a computerized

control system that can be programmed

by the user and that provides both automation and options for manual control. The control system can be set to

maintain steady Mars-like conditions or

to impose temperature and pressure

variations of a Mars diurnal cycle at any

given season and latitude. In addition,

the MEC can be used in other areas of

research because it can create steady or

varying atmospheric conditions anywhere within the wide temperature,

pressure, and composition ranges between the extremes of Mars-like and

Earth-like conditions.

The MEC (see figure) includes access

ports for installation and removal of experimental devices, and vacuum-feedthrough ports for connecting to the devices from the outside. Also included are

feed-through ports for pressure sensors,

thermocouples, and gas-supply tubes that

are permanent parts of the apparatus.

There also are access ports for visual monitoring of experimental devices.

The temperature in the chamber can
NASA Tech Briefs, August 2005 23

range from a minimum of 150 K to a maximum of 473 K. The temperature at 48

different locations within the chamber is

monitored by use of thermocouples. Temperature is controlled mainly by balancing (1) the inward leakage of heat from

ambient temperature against (2) the removal of heat by circulation of a mixture

of warm gaseous nitrogen and cold vaporized liquid nitrogen through a cooling

shroud inside the chamber. The rates of

flow of the warm and cold nitrogen are

monitored by flowmeters and regulated

by controllable valves. Additional heating

is provided by tape heaters outside the

chamber and additional cooling by a liquid-nitrogen cold plate.

Following initial evacuation, the

chamber is backfilled with an atmospheric gas mixture (e.g., CO2 with small

amounts of N2, Ar, O2, and H2O to simulate the Martian atmosphere) at low

pressure [typically between 6 and 9 millibars (between 600 and 900 Pa) for the

Martian atmosphere]. Thereafter, pressure is brought to and maintained at the

required value by use of a feedback control system that balances the rate of flow

of atmospheric gas into the system

against the rates of leakage and of vacuum pumping. The feedback control

system includes a pressure sensor and a

gas-feed throttle valve.

The composition of the gas is monitored by use of a separately operated

residual-gas analyzer, the output of which

is sent to the computerized control system. A mass flow controller maintains

the desired relative concentrations of the

gases in the atmospheric gas mixture.

A programmable logic controller

(PLC) is the heart of the computerized

control system. The PLC accepts inputs

from a manual control panel, capacitance manometers, flowmeters, pressure

controllers, and thermocouples. The

PLC provides outputs to indicators on

the manual control panel, and to the

vacuum, heating, cooling, pressure, and

gas-composition systems described

above. Numerous outputs are sent to a

graphical user interface (GUI) that features “soft” controls and indicators that

emulate those of the manual control

panel with the addition of elaborate

graphical management capabilities. The

GUI notifies the PLC when it is ready to

accept or provide information relative to

the control process. Optionally, the operation of the MEC can be controlled by

use of the manual control panel alone,

or partly by use of the manual control

panel and partly by use of the GUI. This

option affords flexibility for manually

performing tests while maintaining safe

operation by use of automatic control.

This work was done by Carlos Calle and Dean

C. Lewis of Kennedy Space Center, and Randy

K. Buchanan and Aubri Buchanan of VirCon

Engineering. For further information, access

http://technology.ksc.nasa.gov/WWWaccess/

techreports/2001report/200/207.html. 

KSC-12590

The Mars Electrostatics Chamber has an external length of 2 m, external diameter of 1.3 m, and interior volume of 1.5 m3

. The chamber houses an experiment deck measuring 1.43 by 0.80 m. This apparatus is versatile enough to be useful for general research in addition to research on electrostatics in

the Martian environment.

Automated Electrostatics Environmental Chamber

Lyndon B. Johnson Space Center, Houston, Texas

A solid-phase extraction (SPE)

process has been developed for removing alcohols, carboxylic acids, aldehydes, ketones, amines, and other polar

organic compounds from water. This

process can be either a subprocess of a

water-reclamation process or a means

of extracting organic compounds from

water samples for gas-chromatographic analysis. This SPE process is an

attractive alternative to an Environmental Protection Administration liquid-liquid extraction process that generates some pollution and does not

work in a microgravitational environment. In this SPE process, one forces a

water sample through a resin bed by

use of positive pressure on the upstream side and/or suction on the

downstream side, thereby causing organic compounds from the water to be

adsorbed onto the resin. If gas-chromatographic analysis is to be done,

the resin is dried by use of a suitable

gas, then the adsorbed compounds

are extracted from the resin by use of

a solvent. Unlike the liquid-liquid

process, the SPE process works in both

microgravity and Earth gravity. In

comparison with the liquid-liquid

process, the SPE process is more efficient, extracts a wider range of organic compounds, generates less pollution, and costs less.

This work was done by Richard Sauer of

Johnson Space Center, Jeffrey Rutz of Krug

Life Sciences, and John Schultz of Wyle Laboratories. 

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

to the Patent Counsel, Johnson Space Center,

(281) 483-0837. Refer to MSC-22899.
24 NASA Tech Briefs, August 2005

Estimating Aeroheating of a 3D Body Using a 2D Flow Solver

Lyndon B. Johnson Space Center, Houston, Texas

A method for rapidly estimating the

aeroheating, shear stress, and other

properties of hypersonic flow about a

three-dimensional (3D) blunt body

has been devised. First, the geometry

of the body is specified in Cartesian coordinates. The surface of the body is

then described by its derivatives, coordinates, and principal curvatures.

Next, previously relatively simple equations are used to find, for each desired

combination of angle of attack and

meridional angle, a scaling factor and

the shape of an equivalent axisymmetric body. These factors and equivalent

shapes are entered as inputs into a previously developed computer program

that solves the two-dimensional (2D)

equations of flow in a non-equilibrium

viscous shock layer (VSL) about an axisymmetric body. The coordinates in

the output of the VSL code are transformed back to the Cartesian coordinates of the 3D body, so that computed

flow quantities can be registered with

locations in the 3D flow field of interest. In tests in which the 3D bodies

were elliptic paraboloids, the estimates

obtained by use of this method were

found to agree well with solutions of

3D, finite-rate-chemistry, thin-VSL

equations for a catalytic body.

This work was done by Carl D. Scott and

Irina G. Brykina of Johnson Space Center. For further information, contact the

Johnson Innovative Partnerships Office at

(281) 483-3809.

MSC-23126
NASA Tech Briefs, August 2005 25

Information Sciences

Artificial Immune System for Recognizing Patterns

This method offers robust performance in analysis of large sets of data. 

NASA’s Jet Propulsion Laboratory, Pasadena, California

A method of recognizing or classifying

patterns is based on an artificial immune

system (AIS), which includes an algorithm and a computational model of

nonlinear dynamics inspired by the behavior of a biological immune system.

The method has been proposed as the

theoretical basis of the computational

portion of a star-tracking system aboard

a spacecraft. In that system, a newly acquired star image would be treated as an

antigen that would be matched by an appropriate antibody (an entry in a star

catalog). The method would enable

rapid convergence, would afford robustness in the face of noise in the star sensors, would enable recognition of star

images acquired in any sensor or spacecraft orientation, and would not make

an excessive demand on the computational resources of a typical spacecraft.

Going beyond the star-tracking application, the AIS-based pattern-recognition

method is potentially applicable to pattern-recognition and -classification

processes for diverse purposes — for example, reconnaissance, detecting intruders, and mining data.

This AIS method is capable of efficient analysis of large sets of data, including sets that are characterized by

high dimensionality and/or are acquired over long time intervals. When

the method is used for unsupervised or

supervised classification, the amount of

computation scales linearly with the

number of dimensions and offers performance that is both (a) nearly independent of the total size of the set of

data and (b) equal to or better than the

performances of traditional clustering

methods. When used for pattern recognition, the method efficiently finds appropriate matches in the data. The

method enables efficient classification

of a high-dimensional set of data in a single pass through the data, and quickly

flags outliers in much the same way as

the human immune system produces antibodies to invading antigens.

The AIS model in this method is embodied in a set of partial differential

equations that approximate some aspects of the dynamics of a network of immune-system B cells: 

where bi is the number of cells of clone i,

t is time, s is a rate of influx, p is a maximal

growth rate, θ is a growth clone-size

threshold, f(hi,h′

i) is a cell activation function, hi is a binding field, h′

i is a cross-linking field, KiA is a measure of the affinity of

a clone-i antibody for the antigen (the

pattern to be recognized), and d is a death

rate. The functions f(hi,h′

i), hi, and h′i are

defined by additional equations that must

be omitted here for the sake of brevity.

Suffice it to say that the cell activation

function, f(hi,h′

i), depends on the binding

between the B-cell populations in the network. Cells having greater affinity with the

incoming pattern (cells representing

closer matches to the pattern) clone

themselves (with or without mutation)

faster than do those having lesser affinities (representing poorer matches).

The unsupervised classification process

for this model starts with a single sequential presentation of the data to a randomly

initialized set of cell populations. As a result of this mode of presentation, the

amount of computation in the classification process is of the order of a number

proportional to the number of dimensions of the input data. An affinity radius

around each incoming pattern is used to

cull the number of clone populations that

respond each time. The system is allowed

to evolve in time, and the clone population that survives is used as the class for

each pattern. Typically, 10 to 20 computational cycles are all that are needed for

convergence for each incoming item.

∂

∂

= +

+ ′ + −

⎡

⎣

⎢ ⎤

⎦

⎥ b

t

s b p

b fh h K d i

i

i

i i i

θ

θ (, ) A

Spectral Images and Attribute Images derived from spectral images were generated from images of the Marquesas Islands acquired by a spaceborne imaging spectrometer in 18 wavelength bands at 36-km resolution. AIS classification of the data of the 18 images yielded an image in which Islands can be

discerned more easily.
26 NASA Tech Briefs, August 2005

The method has been demonstrated by

applying it to a high-dimensional data set

representing images, synthesized from images acquired by a spaceborne imaging

spectrometer in 18 wavelength bands, that

show various attributes of the Marquesas

Islands and vicinity (see figure). Details of

individual islands are difficult to discern in

any one of the images, but after classification of the image data by the present AIS

method, the dominant island groups can

be discerned more easily.

This work was done by Terrance Huntsberger of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained

in a TSP (see page 1).

The software used in this innovation is

available for commercial licensing. Please

contact Karina Edmonds of the California

Institute of Technology at (818) 393-2827.

Refer to NPO-40256.

The Cryogenic Tank Analysis Program

(CTAP) predicts the time-varying thermodynamic state of a cryogenic fluid in

a tank or a Dewar flask. CTAP is designed to be compatible with EASY5x,

which is a commercial software package

that can be used to simulate a variety of

processes and equipment systems.

The need for CTAP or a similar program arises because there are no closedform equations for the time-varying thermodynamic state of the cryogenic fluid in

a storage-and-supply system. Manual calculations cannot incorporate all the pertinent variables and provide only steadystate solutions of limited accuracy. The

heat energy flowing into and out of the

system, the inflow and outflow of fluid,

the thermal capacitance and elasticity of

the storage vessel, and the thermodynamic properties of the cryogenic fluid at

each instant of time are needed. In other

words, to define the time varying state of

the cryogenic fluid, it is necessary to calculate all the pertinent variables and iterate quasi-steady-state solutions at successive instants of time. It is impractical to

attempt to do this without the help of a

computer program.

The basic tank system (see figure)

modeled in CTAP consists of a pressure

vessel (the tank) that contains the cryogen; the insulation on the tank; the tank

supports; and the fill, vent, and outflow

tubes. The thermodynamic system is considered to be bounded by the outside

surface of the pressure vessel, with provisions for flow of both liquid and gas into

or out of the tank. The volume of the

tank is treated as a variable to account for

contraction and expansion of the pressure vessel with changes in pressure.

The mathematical model implemented in CTAP is a first-order differential equation for the pressure as a function of time. The equation is derived as a

quasi-steady-state expression of the first

law of thermodynamics for the system regarded as closed and isothermal. The

equation includes terms for the parasitic

leakage of heat through the insulation,

for pressurization energy (supplied by

heaters) to be added to the tank fluid,

for expulsion of liquid or vapor, for the

thermal capacitance of the tank wall, and

for stretching of the tank under pressure. CTAP incorporates fluid-property

subroutines based on equations of state

developed at the National Institute of

Standards and Technology. At present,

the fluids represented in CTAP are hydrogen and oxygen.

CTAP is set up as a large subroutine to

be called from within EASY5x. CTAP requires 28 input variables and returns 12

values for use in execution of EASY5x.

The input variables define the fluid

(oxygen or hydrogen), the initial state of

the fluid, the tank and its parameters,

the thermal environment, and the fluid

scenario (defined next). The user can

select any one of the following 12 options or fluid scenarios:

1. Program calculates rates of boil-off or

expulsion for a supercritical fluid at

constant pressure.

2. Program calculates rate of expulsion

of liquid at constant pressure.

3. Program calculates rate of expulsion

of vapor at constant pressure.

4. Program calculates the rate of increase of pressure under a condition

of tank lockup.

5. Program calculates the rates of inflow

of heat required for a given mass flow

rate of supercritical fluid at constant

pressure.

6. Program calculates the rates of inflow

of heat required for a given mass flow

rate of liquid at constant pressure.

7. Program calculates the rates of inflow

of heat required for a given mass flow

rate of vapor at constant pressure.

8. Program simulates tank blowdown —

the expulsion of initially supercritical

fluid from the tank. This calculation

includes effects of stretching of the

tank under pressure.

9. Program calculates variable-pressure

expulsion of liquid under heater and

mass-flow conditions specified by the

user.

10. Program calculates variable-pressure

expulsion of vapor under heater

and mass-flow conditions specified

by the user.

11. Program calculates heat loss through

thermodynamic vent system.

12. Program calculates pressure rise in

the tank from helium pressurant.

Computing the Thermodynamic State of a Cryogenic Fluid

A quasi-steady-state thermodynamical model is iterated over time steps.

Lyndon B. Johnson Space Center, Houston, Texas

Vapor

Pressure Vessel

Heat Inputs

Inflow or Outflow of Vapor

Inflow or Outflow of Liquid

Insulation

Liquid

Vapor

A Cryogenic Fluid and Tank, taken together as a time-varying system, are modeled in CTAP by a quasisteady-state differential equation based on the first law of thermodynamics.
NASA Tech Briefs, August 2005 27

Safety and Mission Assurance Performance Metric

Relevant data are presented in formats that help managers make decisions.

Lyndon B. Johnson Space Center, Houston, Texas

The safety and mission assurance

(S&MA) performance metric is a

method that provides a process

through which the managers of a large,

complex program can readily understand and assess the accepted risk, the

problems, and the associated reliability

of the program. Conceived for original

use in helping to assure the safety and

success of the International Space Station (ISS) program, the S&MA performance metric also can be applied to

other large and complex programs and

projects. The S&MA-performance-metric data products comprise one or

more tables (possibly also one or more

graphs) that succinctly display all of

the information relevant (and no information that is irrelevant) to management decisions that must be made to

assure the safety and success of a program or project, thereby facilitating

such decisions.

S&MA organizations within NASA

have traditionally provided data products that target specific stages of the life

cycles of projects and are generally independent of each other. Such data products have included (1) critical-items lists

(CILs) generated through failuremodes-and-effects analyses (FMEAs);

(2) noncompliance reports (NCRs) —

more specifically, reports of noncompliance with safety requirements as revealed through safety-oriented analyses

and reviews; and (3) problem reporting

and corrective action (PRACA) documents, which are used in tracking and

classifying hardware failures that occur

during testing, assembly, and operations. Notwithstanding the value of

these data products, it is difficult to assess the effects on the overall program

or project from the contents of such a

data product considered by itself. Prior

to the conception of the S&MA performance metric, there was no process

for integrating the individual S&MA

data products into a data product that

could enhance the decisions of program managers.

The S&MA-performance-metric process is one of gathering information

generated according to the various

S&MA disciplines (for example, data

products like those described above).

The gathered information is differentiated into four categories:

• Accepted Risk — This category includes

information from CILs and NCRs. The

critical items and noncompliances can

be classified against specific affected

subsystems of the ISS or other system

that is the focus of the program or

project.

• Anomalies — For the purpose of S&MA,

anomalies are defined as hardware or

software failures, or adverse discrete

events that have occurred during development and operation of the system.

Anomalies include the subject matter of

PRACA reports and of the corresponding reports for software, denoted S/W

PRs. The PRACAs and S/W PRs can also

be classified against specific subsystems.

• Capability Reliability — This category is

particularly relevant to the ISS because

the ISS is being assembled in stages over

a period of several years, and its configuration and required capabilities for each

stage are different. A predicted-reliability

analysis is performed for each capability,

and consequently for each stage. This

analysis is based on the planned times

between assembly flights, the predicted

failure rates of the components, the system architecture, the profile of operations for each stage, and data pertaining

to failures observed in flight.

• Subsystem/Capability Dependencies — The

final piece of the ISS S&MA metric is

the dependency of subsystem and stage

capabilities. One relies on the ISS subsystems to realize the capabilities required at each stage. This dependency

of capabilities upon subsystems provides an integrated system perspective

that helps in the correlation of capability performance with anomalies and accepted risk across subsystems.

This work was done by Jerry Holsomback,

Fred Kuo, and Jim Wade of Johnson Space

Center. For further information, contact Jim

Wade at jwwade@nasa.gov.

MSC-23279

For steady-state solutions, CTAP returns single values (temperatures,

heat flows, and/or mass flows) that describe the state of the cryogenic system. For transient solutions, CTAP returns rates of change of pressure and

density, so that EASY5x can update the

pressure and density accordingly at

each time step, then pass new values of

pressure, density, and any other parameters (e.g., external temperature)

that might change with time back to

CTAP.

This work was done by G. Scott Willen,

Gregory J. Hanna, and Kevin R. Anderson of Technology Applications, Inc., for

Johnson Space Center. For further information, contact:

Technology Applications, Inc.

5445 Conestoga Court, #2A

Boulder, CO 80301-2724

Telephone No.: (303) 443-2262;

www.techapps.com.

Refer to MSC-22862.

NASA Tech Briefs, August 2005 29

Books & Reports

Magnetic Control of 

Concentration Gradient 

in Microgravity

A report describes a technique for rapidly establishing a fluid-concentration gradient that can serve as an initial condition

for an experiment on solutal instabilities

associated with crystal growth in microgravity. The technique involves exploitation of

the slight attractive or repulsive forces exerted on most fluids by a magnetic-field gradient. Although small, these forces can

dominate in microgravity and therefore

can be used to hold fluids in position in

preparation for an experiment. The magnetic field is applied to a test cell, while a

fluid mixture containing a concentration

gradient is prepared by introducing an

undiluted solution into a diluting solution

in a mixing chamber. The test cell is then

filled with the fluid mixture. Given the

magnetic susceptibilities of the undiluted

and diluting solutions, the magnetic-field

gradient must be large enough that the

magnetic force exceeds both (1) forces associated with the flow of the fluid mixture

during filling of the test cell and (2) forces

imposed by any residual gravitation and

fluctuations thereof. Once the test cell has

been filled with the fluid mixture, the magnetic field is switched off so that the experiment can proceed, starting from the

proper initial conditions.

This work was done by Fred Leslie of 

Marshall Space Flight Center and

Narayanan Ramachandran formerly of

Universities Space Research Association. For

further information, contact Paul Hale at

paul.hale@msfc.nasa.gov. MFS-31972

Avionics for a Small Robotic

Inspection Spacecraft

A report describes the tentative design

of the avionics of the Mini-AERCam — a

proposed 7.5-in. (≈19-cm)-diameter spacecraft that would contain three digital video

cameras to be used in visual inspection of

the exterior of a larger spacecraft (a space

shuttle or the International Space Station).

The Mini-AERCam would maneuver by

use of its own miniature thrusters under

radio control by astronauts inside the

larger spacecraft. The design of the MiniAERCam avionics is subject to a number of

constraints, most of which can be summarized as severely competing requirements

to maximize radiation hardness and maneuvering, image-acquisition, and datacommunication capabilities while minimizing cost, size, and power consumption.

The report discusses the design constraints, the engineering approach to satisfying the constraints, and the resulting iterations of the design. The report places

special emphasis on the design of a flight

computer that would (1) acquire position

and orientation data from a Global Positioning System receiver and a microelectromechanical gyroscope, respectively;

(2) perform all flight-control (including

thruster-control) computations in real

time; and (3) control video, tracking,

power, and illumination systems.

This work was done by Larry Abbott and

Robert L. Shuler, Jr., of Johnson Space Center. For further information, contact the Johnson Innovative Partnerships Office at (281)

483-3809.

MSC-23315

Simulation of Dynamics of a

Flexible Miniature Airplane

A short report discusses selected aspects

of the development of the University of

Florida micro-aerial vehicle (UFMAV) —

basically, a miniature airplane that has a

flexible wing and is representative of a

new class of airplanes that would operate

autonomously or under remote control

and be used for surveillance and/or scientific observation. The flexibility of the

wing is to be optimized such that passive

deformation of the wing in the presence

of aerodynamic disturbances would reduce the overall response of the airplane

to disturbances, thereby rendering the airplane more stable as an observation platform. The aspect of the development emphasized in the report is that of

computational simulation of dynamics of

the UFMAV in flight, for the purpose of

generating mathematical models for use

in designing control systems for the airplane. The simulations are performed by

use of data from a wind-tunnel test of the

airplane in combination with commercial

software, in which are codified a standard

set of equations of motion of an airplane,

and a set of mathematical routines to compute trim conditions and extract linear

state space models.

This work was done by Martin R. Waszak of

Langley Research Center. Further information is contained in a TSP (see page 1).

LAR-16414-1


National Aeronautics and

Space Administration