NASA/TMm1998-112216

Director's Discretionary Fund Report for Fiscal Year 1997

Ames Research Center, Moffett Field, California

National Aeronautics and

Space Administration

Ames Research Center

Moffett Field, California 93035-1000

March 1998
NASA Center for AeroSpace Information

800 Elkridge Landing Road

Linthicum Heights, MD 21090-2934

Price Code: A 17

Available from:

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Price Code: A 10
Contents

Introduction .............................................................................................................................

Section 1: Final Reports

Software Interface Analysis Tool (SIAT) ............................................................................

John C. Hinkle, Steven Easterbrook, and Randy Hefner

The Development of a Micromachined Gas Chromatography System for Future

Planetary Missions ............................................................................................................

Daniel R. Kojiro, Thomas C. Shen, and James T. Suminto

Planetary Wind Sensor ......................................................................................................

Paul Kolodziej, Louis J. Salerno, David W. Bogdanoff, Gregory R. Wilson,

Rachael V. Coquilla, Thomas Kowalski, and J. Francisco Soriano

Quantitative Characterization of Porous TPS Microstructures Using Laser

Scanning Confocal Microscopy ............................................................................................

Frank Milos, Jochen Marschall, and Joanne Frerich

NASA Ames Astrobiology Academy ...................................................................................

Douglas A. O'Handley

Does Ultraviolet Radiation Affect Carbon Isotope Fractionation? .......................................

Lynn Rothschild, David Des Marais, Aruna Balakrishnan, and Anne Tharpe

Use of Evolving Microbial Systems as a Domain for Development of Autonomous

Artificial Intelligence Software .........................................................................................

David Thompson, P. Robinson, R. Mancinelli, D. Smernoff, and M. White

Modeling High-Energy Aerocapture Trajectories for Outer Planet Orbiter Missions ..............

Paul Wercinski, Periklis Papadopolo,ls, Ethiraj Venkatapathy, Y-K. Chen,

and Lily Yang

Section 2: Ongoing Reports

Gas-Phase Spectroscopy of Interstellar PAH Analogs .........................................................

Lou Allamandola and Farid Salama

Development of a Tethered-Glider Probe-Positioning System for Use in

Wind Tunnel Testing ..........................................................................................................

Dale L. Ashby and Hiroyuki Kumagai

Visual Servo-Control Applied to Mobile Robot Navigation ................................................

Maria Bualat, Hans Thomas, David Wettergreen, Gary Haith, and Matt Deans

Active Control of Instability Waves in a Laminar Boundary Layer ......................................

Sanford Davis and Anthony Dietz

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The Early History of the Biogeochemical Carbon Cycle Can Be Illuminated by

Isotopic Microanalyses of Rocks Using a UV Laser ...............................................................

David J. Des Marais

Remembering To Do Things in Dynamic Environments ..........................................................

Key Dismukes, Roger Remington, and Maria Stone

Martian Fossils in the ALH84001 Meteorite: An Independent Assessment of

the Evidence ......................................................................................................................

Jack D. Farmer and David Blake

Remote Sensing of Aircraft Contrails Using a Field Portable Imaging Interferometer ............

Philip D. Hammer, William H. Smith, Stephen Dunagan, and Anthony Strawa

A Modeling Approach to Global Land Surface Monitoring with Low-Resolution

Satellite Imagery ..............................................................................................................

Christine A. Hlavka, Jennifer Dungan, and Gerry P. Livingston

Laminar Flow Fairings for Acoustic Sensors and Arrays .......................................................

Clifton Horne, Kevin James, and Chris Allen

Calculation of the Free Energy, Thermal Energy, and Entropy of Self-Assembling

Nanostructures in Solutions ................................................................................................

Richard L. Jaffe and Timur Halicioglu

Study and Design of Carbon Nanotube Electronic Devices ....................................................

Richard L. Jaffe, fie Han, P. M. Anantram, and H. Dai

Application of Unsteady CFD and Sensorless Adaptive Control for the

Development of a Long-Term Left Ventricular Assist Device (LVAD) ..................................

Dochan Kwak and Cetin Kiris

Demonstration of a 7 Kelvin Pulse Tube Cooler Using Rare Earth Regenerators .....................

Jeffrey M. Lee and Peter Kittel

Wireless Video Measurements of Rotor Blade Displacement and Deformation .....................

Douglas L. Lillie and Alan J. Wadcock

Validation of a Nose-Channel Concept for Supersonic Drag Reduction .................................

Mark E. Newfield and Stephen M. Ruffin

Simulation Modeling Investigations of the Terrestrial Carbon Cycle ...................................

Christopher Potter, Steven Klooster, and Vanessa Brooks

Adaptation of Bone to Mechanical Stimulation: Development and

Characterization of a Unique Osteoblast Loading System ...................................................

Nancy D. Searby, Emily Morey-Holton, Ruth Globus, Ekhson Holmuhamedov,

Conrad Macy, and Harry Yee

Dexterous Walking for Mobility in Unstructured Terrain .....................................................

Michael Sims, David Wettergreen, Hans Thomas, John Bares, and

Dimitrious Apostolopolous

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The Origin and Control of 3-D Phenomena in Nominally 2-D Flows ..................................

Murray Tobak and Jonathan H. Watmuff

Super Low Thermal Conductivity and Low-Density Ablative Composites ..........................

Huy Tran and Christine Johnson

A Deployable Vortex Diffuser for Reducing Blade-Vortex Interaction Noise .....................

Chee Tung and Ken McAlister

Adaptation to Virtual Gravitational Environments ...........................................................

Robert B. Welch, Michael Aratow, Robert Whalen, Wanda L. Boda, and Alan Hargens

Fastenerless Structural Connections for Tiltrotor Aircraft ..................................................

John Zuk and Clem HieI

Appendix A-l: Final Reports

Appendix A-2: Ongoing Reports

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V

Introduction

The Director's Discretionary Fund (DDF) at Ames Research Center was established to fund innovative,

high-risk projects in basic research that are essential to our future programs but otherwise would be

difficult to initiate. Summaries of individual projects within this program are compiled and issued by

Ames each year as a NASA Technical Memorandum.

These summaries cover 8 final and 24 ongoing projects in Fiscal Year 1997.

The contents are listed alphabetically according to the last name of the primary investigator in two

sections (final and ongoing reports). Following the narrative reports, two appendixes (for final and

ongoing reports) contain brief descriptions with the financial distribution and status of each of the

projects.

Any questions can be addressed to an investigator directly.

vii

Section I

Final Reports

Software Interface Analysis Tool (SIAT)

Investigator(s)

John C. Hinkle, NASA Software IV&V Facility,

100 University Drive, Fairmont, WV 26554

Steven Easterbrook, NASA/WVU Software

Research Lab, 100 University Drive,

Fairmont, WV 26554

Randy Hefner, Intermetrics, Inc.,

100 University Drive, Fairmont, WV 26554

Objectives of the study

To improve effectiveness, productivity, and quality

of external interface source code analysis for large,

complex, distributed systems being developed in the

Ada programming language.

Many of the large software systems being built

today are highly distributed, with complex interactions between the software components. Interfaces

between software components are particularly hard

to verify for correctness, and are, therefore, a major

source of software hazard. Interface errors have

been implicated in the majority of software failures,

especially those in large, safety-critical applications.

Such errors have numerous causes, related to the

difficulty of coordinating many separate developer

organizations working in parallel. The interfaces

between components written by different organizations are defined in Interface Control Documents

(ICDs). However, it is a complex task to ensure that

each component is consistent with the interface

definitions, and that the changes that occur as the

designs evolve are fully propagated to all the

components that are affected. Each software component may support a multitude of interfaces, and

there may be large variations in the development

maturity across different components and development organizations. Even with the current best

practices in the software industry, many interface

errors are not detected until system integration or

later.

Existing tools provide very little support for

verifying that interactions between components in

the as-built system conform to the specification. A

major weakness is in the ability to trace dataflows

across subsystem boundaries. Verifying that the

sender is providing the right data at the correct

rates, units, and format that the receiver expects

and needs is often a difficult and tedious process.

Weaknesses in the ability to specify and manage

software interfaces, together with the inherent

difficulty in verifying external interfaces during the

code and unit test phase often result in complications during system integration and test. When

problems proliferate to this point, cost, schedule,

and mission are jeopardized.

The long-term objective is to build the tool

infrastructure necessary for performing verification

and validation (V&V) on the new generation of

complex, distributed systems. As software systems

get larger and even more complex, dependence on

manual inspection as the means for verifying

software interfaces and determining impacts on

proposed changes must be minimized. The ability

to adequately perform V&V will depend on the level

of tool support that is available to assist the V&V

practitioner in efficiently locating and verifying

interface data and the related dataflow. The primary

objective of this research effort was to identify and

prototype new tool capabilities to support the

interface analysis process, by:

• extending existing code navigation and

browsing facilities to encompass the tracing of

dataflow, data use, and data dependencies

between Computer Software Configuration

Items (CSCIs), and

• developing new techniques for performing

consistency analysis between the implemented

CSCIs, the design models, the documented

software specifications, and interface definitions

in the ICDs.

Progress and results

The hypothesis was that there is a correlation

between certain programming language constructs

and the implementation of distributed system

external interfaces, and that, therefore, enough

information can be extracted through static analysis

of source code, guided by operator queries, to

support dataflow analysis across software interfaces.

A study was performed against Ada source code

from three International Space Station (ISS) CSCIs to

test this hypothesis. After examination, it was

concluded that certain programming constructs are

indeed used in the implementation of CSCI to CSCI

data interfaces for distributed systems. On the
ISS program, a synchronous 1553 avionics bus

implementation has been adopted.

Significance of the results

The SIAT phase 1 prototype provides ISS analysts

with an initial capability to locate, find dependencies, show utilizations, and follow external interfacerelated data items in the source code units. This

SIAT prototype is a significant step forward in

providing tool support tailored to the needs of the

V&V practitioner. Although numerous commercial

off-the-shelf (COTS) products can be effectively

utilized in performing V&V, they focus primarily on

development or testing activities. The prototype

demonstrates that an approach to interface analysis

based on guided search for interface-related

programming constructs is viable, and that this

approach will facilitate the analysis of dataflows

across the distributed system.

This initial capability is an improvement over

what was previously available for the review of

most of the ISS source code. To date, ISS source code

has been reviewed in a variety of ways, depending

on the development approach taken by the various

CSCI development organizations. Some source code

review is being performed via the McCabe tool set,

which does not include much in terms of data type

and data item dependencies, utilizations, and

navigation. The main benefits garnered from the

McCabe tool set are maintainability and reusability

metrics and test-related data points, rather than

interface analysis. Other portions of the ISS code are

being generated by the MatrixX product design,

development, and code generation capabilities, so

review is performed both through MatrixX and via

desktop editors or word processors. For interface

analysis, even the initial SIAT capability may

provide a productivity multiplier and increase the

quality of the interface and impact analysis work

performed.

The phase 1 product is a stepping stone in

developing a product that will provide support

for geographically dispersed project members to

perform source code analysis and move in the

direction of automated interface consistency analysis

with ICDs. As a result of SIAT phase 1 research and

prototyping, valuable feedback was obtained and

subsequent SIAT phase 2 development has been

funded as a "Center Initiative." The SIAT efforts that

are being pursued somewhat parallel those of the

HAL language IV&V tool set development, a tool set

which has been used widely throughout the Space

Shuttle program as the preferred code analysis

environment. Significant progress is expected

toward building an Ada V&V tool set capability,

which even improves on some of the capabilities

that are available through the HAL tool set. The

result of the SIAT phase 2 effort will be a product

that can be applied to any Ada-related program to

which V&V is being applied and will advance the

understanding of the V&V process for interface

analysis and the ways in which interface analysis

technology can be extended to other systems and

languages.

Keywords

External interface analysis, Ada source code

analysis, Ada distributed systems
The Development of a Micromachined Gas

Chromatography System for Future Planetary Missions

Investigator(s)

Daniel R. Kojiro, Ames Research Center,

Moffett Field, CA 94035-1000

Thomas C. Shen, SETI Institute,

Ames Research Center

James T. Suminto, MicroTech Scien_fic, Inc.,

Sunnyvale, CA 94086

Objectives of the study

To develop lightweight, low-powo:, micromachined,

gas chromatographic equipment for future planetary

atmospheric probes and soil gas or pyrolytic analysis. A gas chromatography (GC) instrument was

used for the Pioneer Venus mission. However,

future missions, such as the Mars Exploration

Missions, discover missions, and missions to probe

outer planet atmospheres or outer planet moons,

will require further reduction in weight, volume,

and power requirements.

Progress and results

Two problems were found in the micromachined GC

detector constructed last year: (1) the discharge gold

electrode was burned out after two weeks of

operation, and (2) the discharge current was not

stable. For these reasons, two new discharge designs

were produced.

1. Submicrometer-sized field emitter tip discharger

The submicrometer silicon tips emitter has been

demonstrated to produce ions in air or other

gases at atmospheric pressure using very

low voltages (50V). Using this principle, a

submicrometer-sized tip silicon discharge

detector was produced (see fig. 1). A formula

was designed to prepare a sol gel solution

using tetraethoxysilane or tetramethoxysilane,

methanol, ethanol, THF, or methyl tert-butyl

ether. This sol gel was applied both to glass

plate-glass plate and to silicon wafer-glass plate.

Because of the difficulty of bonding Pyrex glass

and the silicon chip, the detector could not

function.

. Microporous silicon surface for discharge

A possible attempt to get light emission out of

silicon is to use nanocrystaUine structures. By

forming porous silicon films with differently

doped wafers and with different anodizing

procedures (see refs. I and 2) the plasma

emission was demonstrated. The second

discharge detector of this study is designed

using this principle.

References

1. Richter, Axel; Steiner, P.; Kozlowski, F.; and

Lang, W.: Current-Induced Light Emission

from a Porous Silicon Device. IEEE Electron

Device Letter, vol. 12, no. 12, Dec. 1991,

pp. 691-692.

2. Kozlowski, F.; Huber, B.; Steiner, P.; and

Lang, W.: Generating a Microplasma with

Porous Silicon- Sensors and Actuatoxs,

vol. A 53, nos. 1-3, May 1996, pp. 284-287.

Keywords

Gas chromatography, Micromachined, Analysis

Glass

;li¢on

Channel

Inlet

Chrome/Gold

d_x_e

Figure 1. Tip silicon discharge detector.
Planetary Wind Sensor

Investigator(s)

Paul Kolodziej and Louis J. Salerno, Ames

Research Center, Moffett Field, CA 94035-1000

David W. Bogdanoff, Thermosciences Institute,

Ames Research Center

Gregory R. Wilson, Arizona State University,

Ames Research Center

Other personnel involved

Rachael V. Coquilla, Arizona State University

Thomas Kowalski, Fusion Design

J. Francisco Soriano, Arizona State University

Objectives of the study

Hot-wire and hot-film wind sensors have been used

on the Mars Viking and Pathfinder missions.

Although much useful data have been obtained

from these sensors, they have certain disadvantages:

1. Possibility of unknown changes of calibration,

particularly in the Martian environment with

sand, dust, and extreme temperature changes;

full recalibration is not possible on Mars

2. Sensitivity to solar heating and heat radiated

from the spacecraft power units

3. Possibility of wire or film breakage caused by

wind-driven dust or sand or extreme

temperature changes

4. Highly nonlinear characteristics, leading to

reduced temperature sensitivity at very high

and low velocities

5. Limited accuracy, typically +10 to 15 percent in

wind velocity, +10 ° in wind direction

The objectives of this study were to evaluate

numerous wind sensing techniques, to rank them,

and then select one or two for evaluation in the

Ames Aeolian Research Facility. The techniques to

be evaluated included:

1. Cup and turbine anemometers and wind vanes

2. Ultrasonic acoustic wind sensors

3. Heat transfer techniques--hot wires, hot films,

etc.

4. Pressure measurement techniques

5. Laser Doppler techniques

6. Measurements of oscillations in wakes behind

cylinders

7. Mechanical deflection techniques

Based upon the performance of the selected

device(s) in the simulated Martian environment,

modifications to the selected technique(s) would be

made and the modified device re-evaluated in the

simulated Martian environment.

Progress and results

First, we summarize the evaluations of the techniques. The cup, turbine, and vane wind sensors

would be expected to have bearing reliability

problems in the Martian environment with windblown sand and extreme temperature changes. Also,

with the very low density of the Martian atmosphere, these techniques may not be sufficiently

sensitive. The difficulties with the heat transfer

techniques were summarized previously. For the

lower wind velocities, the pressure measurement

and mechanical deflection techniques require the

measurement of extremely small deflections, which

would appear to be very difficult to do with sufficient accuracy. Further, since extremely small

deflections are involved, these techniques could

easily be confounded by dimensional changes

caused by the large temperature changes that occur

on Mars. Laser Doppler techniques would appear to

be too complex and require excessive power.

Further, the optics are likely to be degraded by

wind-blown sand. If the seed material is natural

sand or dust, one has no control over it and, therefore, the extent to which it lags behind the gas is

unknown. The oscillation frequency behind a

cylinder has a limited frequency response, so measurement of the frequency is not possible at very low

velocities. Other devices such as hot wires or

pressure gauges are required to measure the oscillation frequency and to determine the frequency and

wind direction. These devices have their own difficulties, as discussed previously. In summary, each of

the described techniques appears to have substantial

difficulties.

The ultrasonic technique was selected for further

study and evaluation. Commercial units of this type

are available for use on Earth. Such a sensor has a

simple, fixed calibration (i.e., the distance between

the elements) that will not change with time. Its

characteristics are linear, with excellent sensitivity

down to zero velocity. It is not sensitive to temperature changes and is robust against wind-blown sand.
It containsnolasers,optics,bearings,orother

movingparts.It doesnotdependuponthe

measurementsof verysmalldeflectionsorflow

oscillationbehindacylinder.Finally,atleastfor

unitsforuseonEarth,thesensoraccuracyisquite

high,+3 percent for wind velocity and :L2° for wind

direction. In the ultrasonic technique, there are 3 or

4 ultrasonic ceramic elements that are placed in a

horizontal plane. Each element can either transmit

or receive ultrasonic acoustic pulses or waves. By

measuring the acoustic transit times in both directions between any pair of elements and knowing the

distance between the elements, one may obtain the

component of the wind speed parallel to the line

between the elements. When this is done for two

different pairs of elements, the absolute wind speed

and direction can be obtained. A model 425A ultrasonic wind sensor was purchased from the Handar

Corporation, Mountain View, California, for preliminary testing and evaluation.

In the Handar sensor, ultrasonic pulse trains are

emitted from a tubular ultrasonic ceramic lead

zirconium titanate (PZT) element, they pass through

the air, and then are received by another identical

PZT element. At each interface between PZT and air

is a large (factor of -10 t) mismatch in acoustic impedance and a corresponding inefficiency in acoustic

transmission. For the Martian conditions, the

acoustic impedance mismatch will be -100 times

worse at each interface and hence, the Handar

sensor in its present form was not expected to

operate under Martian conditions. The sensor was

placed in the Ames Mars wind tunnel and tested at

various pressures, wind velocities, and wind direction angles. Wind velocities ranged from 0 to 28 m/s

and the sensor was tested at several different angles

with respect to the wind. The wind velocity in the

tunnel is independently measured using a pitot

tube. At a pressure of 110 mbar, the Handar sensor

gave reliable results, but the results became

inaccurate and erratic at a pressure of 90-95 mbar.

Since the pressure at the Martian surface is ~6 mbar,

the current Handar sensor would not work satisfactorily on Mars, as expected.

Three techniques that could increase the sensitivity of a Handar type sensor were then examined.

The first was the use of horns. It was concluded that

horns could not provide the necessary increase in

sensiti_'ity and, in any case, they would tend to

disturb the flow substantially and thus compromise

the sensor results. The acoustic impedance mismatch

between the PZT and the Martian atmosphere can,

in principle, be reduced by factors up to -10 if the

PZT element is surrounded by one or more layers of

materials with acoustic impedances between those

of the PZT and the Martian atmosphere. This would

still leave the sensor sensitivity on Mars about 100

times less than that of the current sensor on Earth.

Further, one might anticipate several practical

problems in the use of this graded acoustic impedance stackup on Mars. The large temperature

changes, coupled with the very different thermal

expansion coefficients of the various materials, may

lead to separations between the various annular

layers, which could lead to large decreases in the

efficiency of acoustic transmission. These same

temperature-induced dimension changes could also

lead to large stresses and cracking of the ceramic

PZT elements. The final technique to increase the

sensitivity of the ultrasonic wind sensor is to use

low-intensity sparks to generate the sound waves,

rather than PZT ceramic elements. (PZT elements

would still be used to receive the sound waves.) For

Martian atmosphere conditions, using sparks to

generate the sound waves is about 10 0 times more

efficient than using PZT elements. It was estimated

that the required signal intensity at the receiving

PZT elements could be achieved with a very low

spark power input, 10 -° to 10-3 W.

Fifteen bare PZT elements were obtained

without charge from Handar. As a follow-on to this

research, it is proposed to mount one or two PZT

elements with their sensing circuitry in a bell jar,

together with an appropriate spark source. The bell

jar will be pumped down to Martian atmosphere

density and the spark source operated to demonstrate that adequate signals can be picked up in this

way. After adequate development in the bell jar, the

prototype system will be moved into the Ames Mars

wind tunnel for further evaluation. Ultimately, this

could lead to a space-rated sensor that could be

placed on a future Mars probe.

Significance of the results

On previous Mars lander spacecraft, hot-wire and

hot-film wind sensors have been used. These sensors

have numerous disadvantages. Numerous alternative wind sensing techniques were surveyed, and

the ultrasonic acoustic wind sensor proved to be the

best candidate for an improved Martian wind

sensor. A commercial unit built for use on Earth was

purchased and evaluated in the Ames Mars wind

tunnel. As expected, this commercial unit would

not operate at the Martian atmospheric pressures of

-6 mbar, but would operate satisfactorily only down

to about 110 mbar. Several techniques for increasing

the sensitivity of the sensor were examined, and it
was concluded that, by using sparks to generate

pressure pulses, satisfactory operation could be

obtained under Martian atmospheric conditions.

It is recommended that follow-on experiments and

development work be pursued using spark sound

sources and PZT ceramic sound receivers.

Ultimately, this could lead to a space-rated sensor

that could be placed on a future Mars probe.

Keywords

Martian wind sensor, Ultrasonic wind sensor, Spark

sound source

8
Quantitative Characterization of Porous TPS

Microstructures Using Laser Scanning Confocal

Microscopy

Investigator(s)

Frank Milos, Ames Research Center,

Moffett Field, CA 94035-1000

Jochen Marschall, Eloret Institute,

Sunnyvale, CA 94087

Joanne Frerich, Sandia National Laboratories,

P.O. Box 5800, Albuquerque, NM 87185-0751

Objectives of the study

To explore the capability of laser scanning confocal

microscopy (LSCM) to provide quantitative information about the porous microstructure of various

thermal protection system (TPS) materials. The idea

is to use LSCM to obtain digitally stored representations of the pore structure and to devise computational algorithms to extract numerical values for

such quantities as porosity, surface area per volume,

pore size and orientation distributions, etc. This

information will then be incorporated into various

modeling efforts, such as, e.g., internal radiation

transport and gas flow in fibrous insulations.

Progress and results

• More experimental LSCM data of fibrous

TPS materials have been obtained on LI-2200,

AETB-12, and AETB-20 insulation samples.

• Image processing methodologies(e.g.,edge

definition and enhancement algorithms,

segmentation strategies) have been extensively

explored to maximize the accuracy of digital

reconstructions of fibrous insulation

microstructures.

• The 3DMA program has been used to obtain

quantitative microstructural information

(porosity, specific surface area, connectivity,

etc.) based upon voxel counting, stereological

relationships, and nth order correlation

functions.

• A microstructure analysis program that further

processes outputs from the 3DMA code to

compute fiber orientation and diameter

distributions for fibrous TPS insulations has

been written.

• Energy and mass transport simulation codes

that predict internal radiative properties and gas

permeabilities for fibrous insulations described

by experimentally derived fiber orientation and

diameter distributions have been written.

Keywords

Confocal microscopy, Microstructure, Imaging,

Porous materials, Fibrous materials
NASA Ames Astrobiology Academy

Investigator(s)

Douglas A. O'Handley, Ames Research Center,

Moffett Field, CA 94035-1000

Objectives of the study

To help guide future leaders of the U.S. Space

Program by giving them a glimpse of how NASA

operates. Applicants are chosen for this summer

institute for their scientific accomplishments,

scholarly achievement, and individuality. Another

goal is to provide insight into all the elements that

make the NASA missions possible, while at the

same time assigning the student to one of NASA's

best researchers to contribute toward one of its

missions.

Progress and results

This summer 11 students interested in Earth science,

space science, and space technology were selected

from 10 states and Puerto Rico to participate in the

10-week Astrobiology Academy. Four had just

graduated and 7 returned to complete their studies

in the fall.

The students became Research Associates,

contributing their own ingenuity and individuality

to shape the academy. One important aspect of the

academy is to introduce research associates to the

many facets of NASA that contribute to its success

as an organization.

Students developed an independent, lab-based

project under the direction of NASA scientists,

participated in sessions with leaders in government,

industry, and academia, visited other NASA facilities and fellow scientific institutions, and led a

group project of their choosing.

Significance of the results

The efforts of one participant are expected to lead to

a publication in the scientific literature. All the other

students contributed in significant ways to the

efforts of their principal investigators.

Students visited Dryden Flight Research Center,

the Jet Propulsion Laboratory, and the Desert

Research Institute in Reno, Nevada. Local visits

included Space Systems Loral, Lockheed Martin

Missiles & Space, and Stanford University. By

invitation from the Planetary Society, the students

participated in the Planetfest in Pasadena,

California, and the landing on Mars of the

Pathfinder spacecraft.

Keywords

Astrobiology, NASA Academy, College students,

Summer internships

10
Does Ultraviolet Radiation Affect Carbon Isotope

Fractionation?

Investigator(s)

Lynn Rothschild and David Des Marais, Ames

Research Center, Moffett Field, CA 94035-1000

Other personnel involved

Aruna Balakrishnan, student programs

Anne Tharpe, ManTech Systems Engineering

Corp., 155-A Moffett Park Dr., Ste. 220,

Sunnyvale, CA 94089

Objectives of the study

To determine if ultraviolet (UV) radiation affects

stable carbon isotope ratios. If so, is there an ecologic

(e.g., microbial mat vs. phytoplankton) or taxonomic

(e.g., prokaryote vs. eukaryote, alga vs. plant) correlation with the effect? These data will provide the

basis to present the phenomenon to the scientific

community, to estimate how widespread the phenomenon is, and to suggest ways to begin to elucidate the mechanisms underlying the effect. Ultimately this work could lead to a re-interpretation of

isotopic ratio studies, including a re-interpretation

of the fossil record.

Progress and results

Isotopic measurements and, more specifically, ratios

of I3C to 12C in organic relative to inorganic matter,

play an important role in interpreting biological

activity. In the interpretation of the fossil record,

stable carbon isotope ratios are one of the most

critical sources of data next to morphological fossils.

They are a possible approach for searching for life

on Mars. Stable carbon isotope ratios are playing an

increasingly important role in analyzing global

carbon fluxes, biogeochemical features of modern

ecosystems, and community structure (see ref. 1).

They have even been used to determine diet in

archeological studies.

The stable carbon isotopic composition (8_3C) of

a plant or photosynthetic microorganism growing

on CO: is determined principally by the isotopic

composition of the CO2 as well as any isotopic

discrimination associated with CO2 uptake. Bulk

isotopic composition can be further modified

somewhat by enzymatic discrimination during the

biosynthesis of amino acids, lipids, and nucleotides,

and during respiration. To the extent that UV

irradiation alters the patterns of carbon flow in an

organism, it can also alter isotopic composition.

An experiment was conducted to determine if

UV could affect stable carbon isotope ratios in algal

communities. Screens were set up that filtered out

UVA, UVA + UVB, or a UV-transparent screen, over

two types of microbial ecosystems in Yellowstone;

one dominated by the red alga Cyanidium, and one

dominated by the green alga Zygogonium. After

90 days of the treatments, the samples were collected, frozen, and analyzed. The results indicate

that UV radiation does affect the carbon isotopic

signature.

Experiments were then conducted on radishes

to examine UV effects on isotope fractionation.

Radish seeds were grown in flats on the roof of

the lab under different types of UV screening, with

approximately 50 plants germinating per treatment.

The plants were grown near a blower that controlled

temperature and rotated periodically. Isotopic

analysis of leaf tissue, which as the site of photosynthesis should be the most sensitive to isotopic

shifts, showed no difference among the three

UV treatments: full solar UV + PAR (photosynthetically active radiation, 400-700 nm), -UVB,

and -UVA + UVB. Unlike the microbial mats where

the absence of UV led to a depletion of 13C relative

to nC of several per rail, there was no detectable

difference among plant treatments.

Isotopic discrimination in plant leaves is largest

when the rate at which CO2 is supplied to the

enzyme ribulose bisphosphate carboxylase

(RubisCO) exceeds the enzymatic uptake rate.

Discrimination is suppressed to the extent that CO2

fixation draws down the CO2 concentration inside

the leaves because of leaf stomatal resistance. The

_13C values of the radish plants were identical under

all growth conditions, indicating that the balance

between the rates of CO2 diffusion through the leaf

stomata and CO2 fixation by RubisCO were

unchanged under the three UV irradiation regimes.

In contrast, the 813C values of the microorganisms did increase with higher levels of UV

exposure. This trend cannot be attributed to slower

rates of photosynthesis at higher UV exposures,

11
because8_3Cvalueswould be expected to decrease

with a decrease in the rate of photosynthetic CO2

assimilation, relative to the rate of CO2 supply to

the microbes. This isotopi: trend compels another

interpretation, which invokes changes in carbon

flows elsewhere in metabolism, related perhaps to

the synthesis of nucleotides, proteins, or lipids, or

to respiration. If the influence of UV on isotopi:

discrimination in metabolism could be understood,

it might allow more precise delineation of the

metabolic effects of UV irradiation.

Thus we conclude that UV can affect isotope

fractionation in some, but not all, photosynthetic

organisms.

References

1. Peterson, Bruce J.; and Fry, Brian: Stable Isotopes

in Ecosystem Studies. Annual Rev. EcoL

Sys., vol. 18, 1987, pp. 293-320.

Keywords

Isotope fractionation, Photosynthesis

12
Use of Evolving Microbial Systems as a Domain for

Development of Autonomous Artificial Intelligence

Software

Investigator(s)

David Thompson, Ames Research Center,

Moffett Field, CA 94035-1000

P. Robinson, Caelum-Recom Technologies,

Ames Research Center

R. Mancinelli, D. Smernoff, and M. White,

SETI Institute, Ames Research Center

Objectives of the study

To achieve advances in artificial intelligence (AI)-

based software technology for control, diagnosis,

and repair of complex microbial experimental

systems, and to gain a better understanding of the

role that nitrogen-fixing and denitrifying microbial

systems play in nutrient cycling, atmospheric evolution, and biogeochemical (BGC) cycles on Earth.

Progress and results

Pseudomonas fluorescens, Serratia marscens, and

Clostridium perfringens were all grown in the bioreactor system, each under appropriate conditions,

to determine growth rates and nitrogen use characteristics. C. perfringens was also grown in competition with S. marscens to initiate a series of

competition experiments. These experiments are

being continued in order to test the validity of a

model of the evolution of nitrogen cycling (ref. 1).

The bioreactor system was used for the first realtime demonstration of control using a Livingstone

(model-based autonomy software) qualitative model

of the thermal control subsystem. Integration of

hardware using conventional control software with

advanced AI autonomy software was demonstrated

for several key subsystems (thermal control,

biological modeling). A theory for unifying symbolic

reasoning methods with conventional feedback

control methods was completed and presented.

Significance of the results

The autonomous control software could be applied

within NASA; for example, Advanced Life Support,

Office of Space Science, and Autonomous

Spacecraft.

Publications resulting from the study

Smernoff, D. T.; and Mancinelli, R. M.:

Co-organizers of a Half-Day Symposium

on the Bioreactor System, in the 1998 International Society for Ecological Modeling

Program "Issues in Trophic Systems

Synthesis," Ecol. monographs, 1998

(in preparation).

Robinson, Peter: Autonomous Design and Execution

of Process Controllers for Untended Scientific Instruments. Proceedings of the 1997

1st International Conference on Autonomous Agents, Marina del Rey, Calif.,

Feb. 5-8, 1997, ACM SIGART, New York,

N.Y., pp. 546-547.

References

1. Mancinelli, Rocco L.; and McKay, Christopher P.:

The Evolution of Nitrogen Cycling. Origins

of Life and Evolution of the Biosphere,

vol. 18, 1988, pp. 311-325.

Keywords

Nitrogen cycling, Bioreactor, Autonomy, Control

systems

13
Modeling High-Energy Aerocapture Trajectories for Outer

Planet Orbiter Missions

Investigator(s)

Paul Wercinski, Ames Research Center,

Moffett Field, CA 94035-1000

Other personnel involved

Periklis Papadopolous and

Ethiraj Venkatapathy,

Thermosciences Institute,

Palo Alto, CA 94303

Y-K. Chen, Ames Research Center

Lily Yang, Sterling Software Systems,

Ames Research Center

Objectives of the study

First, to characterize the static aerodynamic coefficients of the axisymmetric biconic shape in realistic

flow conditions representative of actual flight

trajectory, including the lift and drag coefficients of

the entry vehicle at various angles of attack; second,

to calculate the heating distribution over the surface

of the entry vehicle at various trajectory points; and

finally, to determine thermal protection system

(TPS) requirements from the coupled heating distributions at several trajectory points. With this

analysis, an attempt to incorporate approximate

methods of estimating the heating distribution (and

subsequent thermal protection material requirements) with an actual trajectory simulation will be

assessed and performed if appropriate.

Progress and results

A high-fidelity three-degree-of-freedom aerocapture

trajectory simulation code that included all necessary input variables to adequately model atmospheric flight in Neptune's atmosphere was developed. Such variables as vehicle aerodynamics,

planet rotation effects, and atmosphere structure

were included. Subsequently, a comparison of

biconic aerodynamics, which compared Newtonian

predicted lift and drag coefficients with full threedimensional (3-D) Navier-Stokes (NS) solutions

using the General Aerodynamic Simulation Program

(GASP) 3.0, was performed. The solutions used

H2-He finite-rate chemistry and vibrational equilibrium and modeled an axisymmetric biconic shape at

various Reynolds numbers and angles of attack.

With improved aerodynamics, trajectory simulations

were improved. Heating distributions were estimated for the biconic shape over a wide variety of

entry conditions. With the capability to evaluate the

impact of entry parameters such as entry velocity,

lift/drag ratio, etc., on overall aerothermal heating,

it is possible to make design choices that were

previously not possible.

Next the effort focused on refining the entry

trajectory based on improved aerodynamics from

the GASP computational fluid dynamics (CFD)

solutions. GASP was used to compute the 3-D flow

fields in this study. GASP is a finite-volume code

with a variety of solution techniques. An implicit

two-factor approximate factorization algorithm with

relaxation in the streamwise direction was used in

the time integration of the thin-layer NS equations.

Third-order, Van Leer flux vector splitting method

was used to discretize the inviscid fluxes. To prevent

possible oscillations in the solution due to higher

order interpolations, a Min-Mod flux limiter was

used. Blottner curve fits were implemented for all

species in the chemistry model to obtain laminar

viscosity. A simple binary diffusion model in which

the Schmidt number is a constant was implemented

in GASP. The thermochemistry model used the

species H, H2, and He and a set of the following

three reactions:

H+H+H2 --_ H2+H2

H+H+H _ H2+H

H+H+ He ---) H2+He

Local thermodynamic equilibrium is assumed

and finite-rate chemistry with complete chemistry

source term linearization in the implicit time integration. The implemented model neglects ionization.

The boundary conditions used in GASP are

explicitly integrated. Since the Neptune probe

geometry considered is symmetric about the x-z

plane, only half of the body was considered. The

appropriate boundary conditions are applied such

that the flow quantities are computed by reflecting

the interior values about the x-z plane. For the

inflow boundary conditions, all flow quantities are

14
fixed to the free-stream conditions. The outflow

boundary condition is supersonic, extrapolated from

the interior. The surface of the vehicle is assumed to

be nonablating, with a fixed wall temperature to

3000 K. A no-slip velocity boundary condition and

zero pressure gradient are imposed at the wall.

Figure 1 shows some of the results of the GASP CFD

analysis.

TPS sizing computation was performed using

the Fully Implicit Ablation and Thermal Response

(FIAT) program. The nonablating aerothermal

heating history was derived using the GASP code.

To account for the heating reduction due to surface

ablation, the blowing reduction parameter of 0.5 was

used in the FIAT computation. The back face of TPS

material was assumed to be adiabatic for conservatism. The initial temperature was 10°C, and the

maximum bond-line temperature used for sizing

was 250°C. The total time for heat soak was 1500 sec.

The candidate TPS materials used in this computation are PICA-15 (15 lb/ft 3) and carbon-phenolic

(90 lb/ft3). The sizing results presented include four

cases. In case 1, the surface is completely covered

with carbon-phenolic, and in case 2, the surface is

covered with PICA-15. The total TPS mass of case 1

(248 kg) is about three times as high as that of case 2

(88 kg). However, the stagnation point recession for

PICA-15 is about 7 cm, and that for carbon-phenolic

is only about I cm. In cases 3 and 4, the surface area

with low heat load is covered with PICA-15 (in

gray), and the rest is carbon-phenolic (in black).

Cases 3 and 4 may reduce the surface recession,

but have higher total mass compared with case 2.

Figure 2 shows results of the TPS sizing.

Significance of the results

The analysis to date has performed calculations

never before undertaken, such as modeling aerocapture trajectories and simulated biconic flow field.

The capability to estimate heating distributions has

enabled evaluating various aerocapture design

issues. This DDF effort has demonstrated the capability to determine high-fidelity aerothermal estimates using CFD tools developed primarily for

Earth environments as well as applying the aerothermal environments to a trajectory-based TPS

sizing estimate. Furthermore, the TPS sizing analysis

has shown the overall feasibility of the concept of

aerocapture at Neptune since the heat-shield TPS

mass estimates are within bounds specified by the

spacecraft designers.

Keywords

Aerocapture, Neptune orbiter, Flow-field

calculations

15
. • . y

Surface Heat Transfer, W/cm z

o.e loeoJ 20oo.o 3eoo.o 4oee.o s_qt..o

Computational Grid, (49x33x33)

Figure 1. GASP CFD solution for surface heating conditions at peak heating (nonablating, t = 149 s).

Casel Case 2 Case 3 Case 4

Carbon Phenolic 248 kg 0 58 kg 96 kg

(black)

PICA-15 0 88 kg 74 kg 62 kg

(gray)

Total 248 kg 88 kg 132 kg 158 kg

Figure 2. Preliminary TPS sizing for Neptune aerocapture vehicle. Assumptions include: backface condition: adiabatic

wall; initial temperature: 10°(7.;bond-line temperature: 250°C; time (final): 1500 sec; total TPS area: 5.3 m'.

16
Section 2

Ongoing Reports

Gas-Phase Spectroscopy of Interstellar PAH Analogs

Investigator(s)

Lou Allamandola, Ames Research Center,

Moffett Field, CA 94035-1000

Farid Salama, SETI Institute, Ames Research

Center

Objectives of the study

To investigate the potential interrelationship

between interstellar polycyclic aromatic hydrocarbons (PAHs) and the carriers of the diffuse interstellar bands (DIBs). The goal is to measure, for the

first time, the gas-phase spectra of selected neutral

and ionized interstellar PAH analogs to allow a

decisive test for these species as potential DIB

carriers. These goals can be achieved by using the

combined techniques of supersonic free-jet expansion spectroscopy (JES) and laser absorption

spectroscopy (LAS).

Progress and results

A feasibility study of the project has been performed

and a new experimental setup for the jet supersonic

expansion has been designed. The feasibility study

consisted of calculating all the optimal experimental

conditions (diameter of the nozzle, size and structure of the expansion chamber, appropriate working

range for the background, and residual pressure)

needed to generate a supersonic jet where the PAH

molecules are vibrationally and rotationally cold

(10 and 100 K, respectively) and fully isolated from

each other. These conditions are essential to simulate

the physical conditions known to exist in the diffuse

interstellar medium and to remove the spectral

congestion observed/expected with such large

polyatomic molecules when probed using more

classical analytical techniques. The experimental

setup required for such a study consists of a highpressure gas reservoir connected to a pulsed nozzle.

The pulsed beam is then expanded in a vacuum

chamber, where it can be probed by a laser. The

vacuum hardware (expansion chamber and precision manipulators), the pulsed nozzle, and the

pumping stations have been either built and/or

ordered. The next step is to mount the supersonic jet

expansion chamber and measure the first ultraviolet,

visible, and near-infrared spectra of a few selected,

free, molecular PAHs in their neutral and ionized

forms.

Keywords

Astrobiology and prebiotic aromatic molecules

and ions; Supersonic jet electronic spectroscopy

(SJES); Polycyclic aromatic hydrocarbons and

environmental studies

or L.e,MP

V

Figure 1. Supersonic jet expansion chamber.

19
Development of a Tethered-Glider Probe-Positioning

System for Use in Wind Tunnel Testing

Investigator(s)

Dale L. Ashby, Ames Research Center,

Moffett Field, CA 94035-1000

Hiroyuki Kumagai, AerospaceComputing, Inc.,

4906 E1 Camino Real, Suite 107, Los Altos,

CA 94022

Objectives of the study

To demonstrate the feasibility of using a tethered

glider with an onboard, miniature, data-acquisition

system and flight-cortrol system as a minimally

intrusive, probe-positioning system in a large-scale

wind tunnel environment.

Progress and results

The design of the glider airframe is currently under

way. An initial configuration has been established,

and aerodynamic analysis and configuration refinement are being performed using the low-o_ier

potential flow panel code PMARC. Results from

PMARC will be used to establish the stability

derivatives that will be used in the flight-control

system. Design of the glider should be complete by

December 1997, with construction to begin in

January 1998.

The glider will have two independent position

and attitude determination systems. The first system

to be used for position and attitude determination is

the onboard inertial navigation system (INS). This

system also provides angular and linear acceleration

information for the flight-control system. The solidstate gyroscopes and linear accelerometers to be

used for the INS have been identified and are being

procured. The software to acquire angular velocity

data and to integrate it for attitude is being

developed.

While the output of the INS can be integrated to

obtain attitude and position information, which is

reasonably accurate over short periods of time,

integration error becomes a problem over long time

periods. Thus a second, absolute, position and

attitude determination system is being explored.

Currently, two systems have been identified that

would meet the requirements for this application.

The first, a local Global Positioning System (GPS)

that uses pseudollites, is being developed at

Stanford University. The second system, which

could be used for absolute position and attitude

determination, is a commercially available opticsbased system known as OPTOTRAK. An

OPTOTRAK system is available at NASA Ames.

The flight-corCrol hardware has been assembled

and tested. The system consists of a PC/104 CPU

and analog to digital converter (ADC) unit and

commercially available servomotoxs. The servomotors are driven by the parallel interface of the

PC/104 flight computer. The flight-cortrol software

is currently being written. The servomotor driver

interface has been written and tested. A manual

emergency backup control system (commercial radio

control) has been purchased for use in the event of a

flight computer failure and also for flight-testing the

glider prior to use in the tunnel.

The miniature data-acquisition system has been

completed and tested. It comprises a PC/104 CPU

and ADC unit. The system can acquire 16 channels

of analog data at a maximum data rate of 500 Hz per

channel. Data are continually transmitted from the

onboard system via free-space infrared link or

twisted-pair wires through an RS-422 port. The

overall size of the complete data system is approximately 3.6 x 3.6 x 4.5 inches.

The tether system for the glider has been

defined. It comprises a single, main tether whose

length is actively controlled using a stepper motor

and controller and a minimum of two safety tethers

that play no role in positioning the glider. The

stepper motor and controller are currently being

tested. The length of the main tether controls the

positions in the wind tunnel that can be reached by

the glider.

Keywords

Flow surveys, UAV, Data acquisition

20
Visual Servo-Control Applied to Mobile Robot Navigation

Investigator(s)

Maria Bualat, Hans Thomas,

David Wettergreen, and Gary Haith

Ames Research Center,

Moffett Field, CA 94035-1000

Matt Deans, Carnegie Mellon University,

5000 Forbes Ave., Pittsburgh, PA 15213

Objectives of the study

To develop a visual approach to short-range and

terminal mobile robot navigation. Visual servocontrol techniques for mobile robots will be developed; these techniques will be implemented on

board under realistic computing and telemetry

constraints; and this approach will be demonstrated

in realistic outdoor field experiments. In addition,

obstacle avoidance techniques will also be integrated

with visual servo-control, and performance will be

quantified and compared to traditional methods.

Progress and results

The hardware, software, and programmatic

infrastructure has been built. A dual Pentium

computer system with video digitizers, a pan-tiltvergence device, and a pair of cameras have been

purchased and integrated into a testbed system. The

basic visual tracking and robot control software for

the new computing platform has been written and

debugged. Finally, discussions have begun with the

Mars 2001 mission to determine how to best apply

this research to Mars exploration.

The major technical results of the first year

address the three dominant failure modes of visual

servo-control: target loss due to robot motion and

subsequent appearance change, above-threshold

correlation for an erroneous target (false positive),

and correlation that slowly drifts off the target

because of weak feature texture. A neural network

system that may solve the first of these problems is

being tested. The neural network predicts the target

shift in the input image based on rover and camera

mount sensor information. Initial results show that

the system reduces the number of tracking failures

by 50 percent or more. To combat the drifting target

problem, a hierarchical correlation scheme in which

two correlations are performed for each control

cycle has been implemented. First, a correlation is

performed at half resolution over a large portion of

the input image. Then a second correlation is made

at full resolution over a smaller search area that is

based on the previous correlation result. This system

has been tested in outdoor trials on the Marsokhod

rover. Discussions with the Jet Propulsion Laboratory about porting this system onto their testbed

rovers are ongoing.

Significance of the results

The ability of robot rovers to reach a wide variety of

samples and perform analyses on each one is crucial

to the success of the surface exploration objectives of

the Mars Surveyor program. Traditional techniques

for spacecraft navigation are unsuitable for roving

vehicles, and worse, they make the vehicle more

complex, heavier, and more vulnerable to failure.

Visually servoed navigation provides an innovative

navigational alternative, consuming little power and

telemetry and making use of imaging hardware

already baselined for proposed rover missions.

Initial results prove the feasiblity of such a system

using the limited computational power of the types

of processors that will fly on the near-term missions.

The visual servoing technique will drastically reduce

the ground-control needs for rover missions, with a

subsequent reduction in mission costs and an

increase in science return.

Keywords

Visual servoing, Computer vision, Robot navigation,

Planetary rovers

21
Active Control of Instability Waves in a Laminar

Boundary Layer

Investigator(s)

Sanford Davis, Ames Research Center,

Moffett Field, CA 94035-1000

Anthony Dietz, MCAT Institute, Ames

Research Center

Objectives of the study

To develop and test an active wave cancellation

scheme for the control of transition in a laminar

boundary layer. The scheme uses distributed disturbance sources to excite control waves that are out of

phase with the boundary layer instability waves

excited by free-stream disturbances. Superposition

of the control waves on the instability waves reduces

the magnitude of the instabilities and hence delays

transition of the flow into turbulence. The use of

spanwise distributed sources for the control wave

introduces the possibility of canceling threedimensional wave packets. Another important

aspect of the investigation is the use of artificially

generated two- and three-dimensional free-stream

disturbances to excite the boundary layer. Repeatable disturbances are necessary to provide a known

input to the control scheme, allowing detailed study

of the cancellation process and optimization of the

control algorithms. When a satisfactory control

scheme has been obtained, it will be evaluated

against random three-dimensional instability waves

excited by free-stream turbulence.

Progress and results

The test plate and control unit have been designed

and manufactured. The control unit consists of an

array of 24 microphones and 8 speakers mounted in

a cavity on the lower side of the test plate. The

mounting arrangements for the microphones and

speakers were determined from tests and analyses

performed to optimize the frequency response of the

sensors. The wind tunnel data acquisition and

processing capabilities have been expanded to cope

with the increased number of channels and the realtime processing requirements of the control unit.

Software control of the new hardware was implemented using LABVIEW graphical programming

software. A technique has been developed to

generate repeatable three-dimensional flee-stream

disturbances to complement the two-dimensional

disturbances generated in the facility by a vibrating

ribbon. A low-aspect-ratio wing made from

0.001-inch stainless steel shim is given a pulse

displacement. When the pulse disturbance from this

wing interacts with a roughness element on the plate

surface, it excites a three-dimensional wave packet

similar to that excited by free-stream turbulence.

Initial testing of the control scheme with twodimensional disturbances is under way, and tests

and optimization with three-dimensional disturbances will continue through the next fiscal year.

Significance of the results

The potential benefits of laminar flow control in

reducing aircraft or ship drag and improving manufacturing processes are large and justify the pursuit

of numerous control techniques. The few wave

cancellation studies carried out previously have

involved surface-generated instability waves or

uncontrolled free-stream-generated waves, limiting

the breadth of the studies and the degree to which

the cancellation technique could be optimized. In

addition, there has been no concentrated effort to

introduce or cancel any three-dimensionality in the

instability waves. The results from this experiment

involving the control of known and repeatable twoand three-dimensional instability waves will add a

wealth of new information on the feasibility of active

transition control.

Keywords

Boundary layers, Laminar flow control, Active flow

control, Transition

22
The Early History of the Biogeochemical Carbon Cycle

Can Be Illuminated by Isotopic Microanalyses of Rocks

Using a UV Laser

Investigator(s)

David J. Des Marais, Ames Research Center,

Moffett Field, CA 94035-1000

Objectives of the study

Stable carbon isotopic measurements of carbon

reservoirs in ancient sedimentary rocks offer a

valuable insight into the early history of our biosphere. For example, the stable isotopes 12C and 13C

are utilized at different rates by biological processes.

Therefore, certain differences in _3C/12C values

between preserved organic matter and inorganic

carbon minerals can be interpreted as "isotopic

fossils" of metabolism. Also, through isotopic mass

balance calculations, changes in the inventories of

sedimentary carbon reservoirs can be charted over

geologic time.

Major advances in interpreting patterns of

_3C/_2C values in ancient rocks will depend upon

our ability to sample in situ very small bits of

carbon-containing material. These challenges could

be met by a microsampler system that volatilizes

sample targets in the size range from 1 to 100 _m.

Such a technique would also greatly facilitate the

analyses of meteorites and planetary materials.

We proposed to develop and verify the performance of a laser-based microsampler that could

reliably release carbon from organic matter or

carbonate in a 3- to 100-_tm-diameter spot size and

convert this carbon to CO 2 for stable isotopic analysis. "Reliably" means that the isotopic discrimination associated with the process is either insignificant or else highly reproducible. Organic carbon

should be combusted quantitatively. Carbonates

should be converted principally to CO 2, and any

other products should also be analyzed to yield

accurate measurements of _3C/_2C and _sO/160.

Ultimately, samples as small as 10 "1°moles should be

produced in order to take full advantage of state-ofthe-art isotope mass spectrometry.

Progress and results

The microsampler incorporates a laser and microscope system that is commercially available. The

frequency quadrupled Q-switched Nd:YAG laser

has a 266-nm output, which will generate up to

1.6 x 1012joules/cm2s onto a spot 10 _tm in diameter.

This laser decomposes carbonates to CO 2 by photoexcitation. The laser can photoexcite organic carbon,

causing it to combust in the presence of Oz. The

laser's power output can be attenuated and the spot

size adjusted from 5 to 300 jzm. The microscope's

view is coaxial with the laser beam and has image

magnifications ranging from 50x to 1000x. A sample

chamber that is movable, relative to the laser beam,

will be constructed using a motor-driven x-y stage.

The sample chamber will be interfaced with our

existing Nuclide 6-60 RMS isotope mass spectrometer, which can analyze samples as small as

10-8 moles. In June, 1998, a Finnegan Delta+ mass

spectrometer that should lower the sample requirement to 10 "1°moles will be acquired. Then previously characterized carbonate rocks will be analyzed

to verify that the new technique recreates the 13C/_2C

patterns previously recognized among the various

generations of carbonate.

Significance of the results

A major objective of exobiology is to interpret the

early evolution of life on Earth and to search for

evidence of prebiotic and/or biologic evolution

elsewhere in the universe. A key part of this evidence resides in rocks that have incorporated the

remains of biota and/or prebiotic organic matter.

This material is preserved at the submillimeter size

range. Therefore, a need clearly exists to perform

microanalyses at the scale of tens of _tm or less.

There are several novel elements in this work.

This is the first use of an ultraviolet (UV) laser for

isotopic microanalysis. This will be the first laserassisted combustion of organic carbon for stable

isotopic analysis. Also, these will be the first

subnanomole-sized carbon samples to be measured

isotopically.

The addition of this laser system will help to

establish Ames as a leader in the isotopic microanalysis of a wide variety of extraterrestrial materials of interest to exobiology. Advanced methods

in microanalysis will help to position Ames as a

23
possiblefuturerecipient of a returned Mars sample,

which is now a key objective for the currently

funded Mars Surveyor Program.

Keywords

Laser, Rocks, Carbon

24
Remembering To Do Things in Dynamic Environments

Investigator(s)

Key Dismukes, Roger Remington, and

Maria Stone, Ames Research Center,

Moffett Field, CA 94035-1000

Objectives of the study

To develop an experimental paradigm with which

to study prospective memory for the types of tasks

performed by air traffic controllers; and to determine factors that influence the probability of

prospective memory (PM) errors.

Progress and results

The following tasks have been performed:

• Review of the relevant scientific literature

* Review of National Transportation Safety Board

(NTSB) accident reports

• Review of Aviation Safety Reporting System

(ASRS) incident reports involving controller

errors

• Controller interviews

• Development of a conceptual framework for the

cognitive mechanisms underlying prospective

memory errors

• Design of an experimental paradigm for

prospective memory tasks analogous to those of

controllers

Although literature on memory research

abounds, most studies address retrospective memory,

in which an experimenter gives subjects some material to memorize and at some later time asks the

subjects to recall the content of the material. By

contrast, in prospective memory, subjects must

remember an intention to perform some action that

must be deferred. The conceptual framework of the

present study posits that PM does not require

unique cognitive mechanisms but rather draws

upon general memory mechanisms in unique ways

because of the nature of the task. The study hypothesizes that success or failure at PM hinges on:

• The elaboration of the intention in long-term

memory

• The availability of environmental cues to trigger

retrieval of the stored intention at the appropriate time

• The nature of other tasks ongoing at the time the

PM task is to be performed

The main experimental paradigm consists of a

visual display in which targets with associated

datablocks enter and leave a rectangular pattern

controlled by the subject. At irregular intervals, the

subject is instructed to cause one of the targets to

deviate from the normal routing when it reaches a

predetermined point, and the subject must remember this instruction. With this paradigm, a range of

pertinent factors can be manipulated, including the

duration the intention must be retained; the availability and character of cues to remind the subject of

the intention; the workload of the ongoing task; and

the relationship of the PM task to the ongoing task.

This somewhat complicated paradigm is currently

being programmed. In addition, data are being

collected with a simpler experimental paradigm in

which subjects' performance is examined when the

window of opportunity to perform is defined by

time rather than an event-based trigger.

Keywords

Prospective memory, Air traffic controllers, Memory

for intentions

25
Martian Fossils in the ALH84001 Meteorite:

An Independent Assessment of the Evidence

Investigator(s)

Jack D. Farmer and David Blake, Ames

Research Center, Moffett Field, CA 94035-1000

Objectives of the study

To re-evaluate the biogenicity of microfossil-like

features found in the Martian meteorite, ALH84001,

based on detailed comparisons to terrestrial analogs

of known origin. To achieve this goal we seek to:

1) use nutrient limitation methods to derive an

empirically based estimate for the lower size limit

achieved by four species of small heterotrophic

microbes from hydrothermal environments considered good analogs for ALH84001; 2) re-evaluate the

biogenicity of features commonly found in terrestrial rocks that have been broadly referred to as

"nanobacteria"; 3) document the effects of contemporaneous mineralization on the fossilization

potential of small bacteria, particularly those found

in hydrothermal environments; and 4) make direct

mineralogical and microstructural comparisons of

terrestrial analogs of known origin and the putative

nanometer-scale microfossils of the ALH84001

meteorite.

Progress and results

Four species of thermophylic heterotrophic bacteria

typical of environments postulated for the Mars

meteorite were successfully isolated and cultured.

Nutrient limitation experiments were used to

evaluate the lower size limit for these species under

conditions of starvation typical of deep subsurface

environments. Critical point drying methods and

scanning electron microscopy were used to characterize experimental cultures and obtain morphometric data on cell size.

Significance of the results

Our culture-based analog studies are important for

providing an experimental framework for testing

hypotheses about what controls the lower size limit

of living cells and for establishing an empirical

lower size limit for life to which theoretical arguments can be compared. In addition, in vitro

biomineralization and fossilization studies are

important for establishing a baseline for comparing

nanoscale morphological features observed in the

ALH84001 meteorite and for ancient rocks on Earth.

The establishment of reliable criteria for recognizing

the biogenicity of morphological structures preserved in ancient rocks is extremely important for

improving our accessibility to the early history of

the Earth's biosphere, and is also essential in

exploring for past life on Mars when samples are

returned to Earth early next century.

Keywords

Mars, Meteorite, ALH84001, Exopaleontology,

Biogenicity, Fossils

26
Remote Sensing of Aircraft Contrails Using a Field

Portable Imaging Interferometer

Investigator(s)

Philip D. Hammer, Ames Research Center,

Moffett Field CA 94035-1000

William H. Smith, Washington University,

St. Louis MO 63130

Other personnel involved

Stephen Dunagan and Anthony Strawa,

Ames Research Center

Objectives of the study

To measure visible and infrared radiative effects of

aircraft contrails to provide information about their

spatial distributions, their microphysical properties

(especially ice crystals), their time evolution, and

their surroundings by application of a novel remote

sensing technique, imaging interferometry. The

instrument concept to be utilized is called DASI

(digital array scanned interferometry). These

measurements will be made from the ground at

appropriately selected sites. Analytical techniques

employing atmospheric radiative transfer methods

will be developed and applied to analysis and

interpretation of the spectral images. The overall

objective is to demonstrate the feasibility of this

measurement technique for remote sensing of

contrail properties, and more generally,

of aerosol plumes.

Progress and results

In early May 1996, measurements were made

during NASA's subsonic aircraft contrail and cloud

effects special study (SUCCESS). Ground-based

measurements were made of aircraft contrails and

cirrus clouds at the Department of Energy's Cloud

and Radiation Testbed (CART) site in Oklahoma.

DASI spectral images were acquired for both

commercial aircraft and SUCCESS mission aircraft

atmospheric radiative effects. These measurements

were acquired together with those of other participating sensors. Simultaneously, airborne and

satellite-based measurements were also acquired

by collaborating investigators.

A new infrared DASI sensor with improved

characteristics has been developed. Additional

ground-based measurements of aircraft contrails

will be made after a new lens system for this sensor

is acquired. The improved infrared instrument

will permit obtaining images with good spatial

resolution over the entire spectral range of 4000 to

11,000 cm -1 (0.91 to 2.0 microns). The anticipated

high-quality measurements will enable completion

of the study.

Significance of the results

The results from the May 1996 measurements have

met the following analysis goals: 1) determination

of spatial features, extent, and short term-time

evolution of the contrails; 2) assessment of spatial

distributions--mapping of variations in cirrus

optical properties; 3) collection of information about

the atmosphere in the vicinity of contrails; and

4) qualitative extinction and scattering optical depth

information. The improved DASI sensor, expected to

be ready during 1998, should allow completion of

the project.

Keywords

Aircraft contrails, Remote sensing, Imaging

spectrometers

27
A Modeling Approach to Global Land Surface Monitoring

with Low-Resolution Satellite Imagery

Investigator(s)

Christine A. Hlavka, Ames Research Center,

Moffett Field, CA 94035-1000

Other personnel involved

Jennifer Dungan, Johnson Controls World

Services, Ames Research Center

Gerry P. Livingston, School of Natural

Resources, University of Vermont,

Burlington, VT 05405-0088

Objectives of the study

A new approach to developing accurate estimates

of global extents of land use/land cover types

with maps derived from satellite imagery is being

developed. This objective is being accomplished by:

1) testing models of the size distribution of patches

of specific cover types, as mapped with imagery of

relatively fine spatial resolution; and 2) developing

numerical procedures for estimating the total area

of these cover types with low-resolution satellite

imagery that incorporate models of size distribution

and effects of pixelation.

Progress and results

At the outset of this project, previous research

results had indicated that the distribution of sizes

of small burn scars in tropical savannas and ponds

in Arctic tundra could be modeled with power or

exponential curves, and a comparison between fire

scars observed with fine-scale imagery [Landsat

multispectral scanner (MSS)] and low-resolution

imagery [advanced very-high-resolution radiometer

(AVHRIR)] had indicated effects of pixelation. Two

additional Landsat data sets have been processed

into maps of bum scars, and analysis of a map

of surface water developed from 100 m Earth

Resources Satellite (ERS-1) imagery has begun.

Analysis of these additional maps of burn scars

and ponds in tundra will support assessment of the

variation of size distribution characteristics in space.

A software module to simulate effects of pixelation

was written as an initial step in developing procedures for improved areal estimates.

Significance of the results

The distributions of sizes of burn scars in tropical

savannas and ponds in Arctic tundra indicate the

important contribution of small patches, with sizes

similar to or smaller than the pixels sizes of satellite

imagery used for regional and global monitoring, to

total area. The ability to model the distributions and

simulate effects of pixelation is expected to lead

improved areal estimates, which in tum will lead to

better estimates of greenhouse gas production and

effects on the energy balance between the Earth's

surface and the atmosphere that are associated with

biomass burning and high latitude wetlands.

Publications resulting from the study

Hlavka, C. A.; and Livingston, G. P.: Statistical

Models of Fragmented Land Cover and the

Effect of Coarse Spatial Resolution on the

Estimation of Area with Satellite Sensor

Imagery. International J. Remote Sensing,

vol. 18, no. 10, 1997, pp. 2253-2259.

Hlavka, C. A.: Statistical Models of Landscape

Pattern and the Effects of Coarse Spatial

Resolution on Estimation of Area with

Satellite Imagery. To be published in a

book on spatial accuracy, co-edited by

H. T. Mowrer and R. G. Congalton, by the

Ann Arbor Press. In review.

Keywords

Satellite imagery, Spatial accuracy, Spatial resolution

28
Laminar Flow Fairings for Acoustic Sensors and Arrays

Investigator(s)

Clifton Home and Kevin James, Ames Research

Center, Moffett Field, CA 94035-1000

Other personnel involved

Chris Allen, Ames Research Center

Objectives of the study

Recent wind tunnel aeroacoustic test programs have

demonstrated the success of using multiple-sensor

microphone arrays to measure the locations of noise

sources due to high-lift systems and propulsion

systems for both subsonic and supersonic transport

aircraft configurations. Accurate measurement of

clean and quiet configurations is presently a difficult

challenge because of high background noise associated with turbulent flow over the sensor fairing.

The present study investigates the feasibility and

effectiveness of using natural laminar flow (NLF)

and suction hybrid laminar flow (HLF) fairings to

reduce the background noise and to control lift. The

goal of this research is to generate design guidelines

for fabrication of fairings for both small and large

arrays for future aeroacoustic research.

Progress and results

The 14-inch subsonic wind tunnel in the Fluid

Mechanics Laboratory has been adapted for development of quiet acoustic sensors, and common

instrumentation and data-acquisition equipment

will be used in the two studies. Two test models

and a test section adapter have been designed, and

fabrication is about 80 percent complete. The first

test model is a NLF fairing with 8-inch chord and

5 microphones. The second model is a HLF model

with 6-inch chord, 3 microphones, and 5 porous

screen suction ports. The airfoil sections were

adapted from the results of previous research

studies and experiments of laminar flow and

minimum turbulent separation configurations.

Predictions of pressure distribution, transition, and

separation locations have been computed for comparison with test results. Research testing should

begin in late 1997 and be completed in early 1998.

Significance of the results

The development of microphone and acoustic array

fairings with reduced background noise will

enhance the value of aeroacoustic testing at Ames

and at other research centers by allowing measurements at further distances, and will permit accurate

measurements of clean (baseline) or advanced quiet

transport configurations that use noise reduction

technology. There are also commercial/military

applications for low-background-noise acoustic

sensors. These studies will also provide new insight

into the role of acoustic receptivity and surface

irregularities in boundary layer transition.

Keywords

Aeroacoustic testing, Acoustic arrays, Laminar flow

29
Calculation of the Free Energy, Thermal Energy, and

Entropy of Self-Assembling Nanostructures in Solutions

Investigator(s)

Richard L. Jaffe, Ames Research Center,

Moffett Field, CA 94035-1000

Timur Halicioglu, Eloret Institute,

Ames Research Center

Objectives of the study

The configurational stability of nanoscale particles is

greatly influenced by the surrounding medium. In

general, the effect exerted by the medium on a

transformation (or combination) reaction is a very

important one, and can influence reaction equilibria

and rates considerably. The objective of this study is

to investigate the effect exerted by the solvent on a

chemical system in equilibrium or undergoing

reaction. The study is expected to provide an atomic

level understanding of the contributions (coming

from the enthalpy as well as the entropy) to various

solvation processes and reaction equilibria and

kinetics.

azobenzene were considered. Investigations were

conducted using a molecular dynamics procedure

for T = 298 K and P = I atm. Simulation calculations

were carried out employing the Dreiding force field

method, and the Ewald sum technique was used to

include long-range interactions. The enthalpy

change, &t-I, for this isomerization reaction in the gas

phase was well predicted. For the same reaction

taking place in water, three main contributions (in

order of importance) to _ coming from (1) changes

in interaction energy among water molecules in the

vicinity of azobenzene, (2) interactions between the

azobenzene molecule and water, and (3) the strain

energy of the azobenzene molecule due to different

configurations were calculated.

Significance of the results

Results indicate that the contribution coming from

water/water interactions, in the vicinity of the

solute, plays the most important role in this

isomerization reaction.

Progress and results

As a prototype system, the effect of aqueous

solutions on the cis-trans isomerization reaction of

Keywords

Solvent effect, Azobenzene, Isomerization

30
Study and Design of Carbon Nanotube Electronic Devices

Investigator(s)

Richard L. Jaffe, Ames Research Center,

Moffett Field, CA 94035-1000

Jie Han, MRJ, Inc., Ames Research Center

Other personnel involved

P. M. Anantram, Ames Research Center

H. Dai, Stanford University,

Palo Alto, CA 94305-4035

Objectives of the study

A carbon nanotube (CNT), a hollow cylinder formed

by rolling over a graphene sheet, can be metallic or

semiconducting, depending on the tube helicity and

diameter. Because of its small feature size, -1-nm

diameter, CNTs can be used as quantum wires for

single electron transistors or heterojunctions for

diodes and transistors. The objective of this work is

to explore, using quantum mechanics calculations

and molecular simulations, the possibilities for

making CNT nanoelectronic devices.

Progress and results

Three types of CNT devices have been designed and

studied:

1. CNT single electron transistor

Metallic 1.4-nm-diameter CNTs can be easily

prepared. This CNT is recommended as a single

electron transistor. On the scale of -1-nm significant quantum jump effects due to transitions of

a single electron are expected. The perfect tube,

made of a hexagonal array of carbon atoms, is

conducting because of the delocalized nature

of the valence electrons. Topological defects can

be created by converting four hexagons to a

pentagon-heptagon-pentagon-heptagon configuration by rotating two adjacent carbon atoms in

the surface of the cylinder. This scenario creates

a barrier for electron transfer and can be considered to be a gate in the transistor. The chemical

pathway for this transition and the chemical/

mechanical stability of the defect site have been

found by using quantum mechanics calculations

and molecular simulations. Local density of

states and conductance calculations suggest that

this device could serve as a single electron

transistor.

2. Two-terminal CNT junction diodes

Scientists at the University of California,

Berkeley, have proposed this type of device.

The purpose of this research is to design synthetically accessible CNT junctions. Extensive

ab initio calculations were performed to identify

attractive candidates. These calculations were

used to observe and collect samples of the

simulated CNT structures. For these observed

structures, electrical property calculations were

performed to support further experimental

studies. The collaborative work on measurement

and modeling of the observed junctions is in

progress.

3. Three-terminal CNT junction transistors

Three-terminal Y and T CNT junctions based on

analogs to conventional p-n-p or n-p-n junctions

are proposed. The topological and chemical

rules have been derived to construct these

junctions. Some of the proposed structures have

been observed experimentally, including T and

Y junction and torus.

Significance of the results

On scientific issues, for the first time, the structural,

chemical, mechanical, and electrical properties of

CNTs have been correlated. Present research has

shown that a small change in one property can

result in a detectable change in other properties,

suggesting that CNTs are ideal for nanoscalemechanical-electrical systems (NEMS).

Technically, the designed CNT devices, if

successful, can take us through the 0.1-micron

barrier for feature size in conventional semiconductor materials. They could be used as computer components, including transistors, and also

NEMS for sensors and interconnects.

Publications resulting from the study

Anantram, M. P.; and Han, J.: Transport through

Uniform Carbon Nanotubes and Junctions.

Lntemational Conference on Molecular

Electronics: Science and Technology,

Humacao, Puerto Rico, Dec. 14-18, 1997.

http://science.nas.nasa.gov/-han/

abstract/icmest97.html.

31
Hart,Jie:Energetics and Structures of Carbon

Nanoconic Tips and Nanotube Junctions.

American Chemical Society National

Meeting, Las Vegas, Nev., Sept. 7-11, 1997.

http://science.nas.nasa.gov/~han/

abstract/acs97html.

Han, Jie: Energetics and Structures of FuUerene

Crop Circles. Chem. Phys. Lett., Dec. 1997.

http://science.nas.nasa.gov/~hart/

cone/cone.html.

Ha_n, Jie: Modeling of Branched (L, Y and T) Carbon

Nanotube Junctions. To be submitted to

Phys. Rev. B.

http://science.nas.nasa.gov/~han/

LYTjunction/LYTjunct-ion.html.

Han, Jie; Anantram, P. M.; Jaffe, R.; and Dai, H.:

Observation and Modeling of Single Wall

Carbon Nanotube Bend Junctions.

Submitted to Phys. Rev. B, 1997.

http://science.nas.nasa, gov / ~ban/

bendjunction/bendjunction.html.

Han, J.; Anantram, M. P.; and Jaffe, R.: Design

and Study of Carbon Nanotube Electronic

Devices. Fifth Foresight Conference

on Molecular Nanotechnology, Paio Alto,

Calif., Nov. 1997.

http://science.nas.nasa.gov/-han/

abstract / fcrrnl.html.

Han, Jie; and Jaffe, R.: Chemical and Mechanical

Stability of Carbon Nanotube Electronic

Devices. 1997 American Vacuum Society

(AVS) Conference at San Jose, Calif.,

Sept. 28-31, 1997.

http://science.nas.nasa.gov/~han/

abstract/avs97b.html.

Hart, Jie; and Jaffe, Richard: Energetics and

Geometries of Carbon Nanocor_c Tips.

To appear in J. Chem. Phys., Feb. 1998.

h ttp://science, n as. nasa. g ov / Pub s /

TechReports/NASreports/NAS-97-015.

Han, Jie; and Jaffe, Richard: Roles of Pentagons

and Heptagons in Carbon Nanotube

Junctions. Submitted to Chem. Phys. Lett.

http: / / science.nas.nasa, g ov/-hart /

defect/defectahtml.

Keywords

Carbon nanotube, Nanoelectronics, Junctions

32
Application of Unsteady CFD and Sensorless Adaptive

Control for the Development of a Long-Term Left

Ventricular Assist Device (LVAD)

Investigator(s)

Dochan Kwak, Ames Research Center,

Moffett Field, CA 94035-1000

Cetin Kiris, MCAT Institute, Ames Research

Center

Objectives of the study

To develop a procedure for designing a long-term

or permanent ventricular assist device (VAD) by

implementing adaptive control in conjunction with

numerical simulations of time-varying pulsatile

flow.

Progress and results

Mechanical blood pumping devices are in demand

as a life support system to assist ailing hearts.

Currently, the commercially available circulatory

support involves large, complex, and expensive

pulsatile devices. These diaphragm-type or cabledriven devices require large, external support

equipment, resulting in little or no patient mobility.

In 1989, NASA/Johnson Space Center (JSC)

began a joint project with the DeBakey Heart

Center of the Baylor College of Medicine in Houston,

Texas, to develop a new, implantable, total VAD

(NASA/DeBakey VAD) complete with a control

electronics package. This VAD is based on a fastrotating axial pump that uses magnetic propulsion,

requiring a minimum number of moving parts. To

make it implantable, the device is to be made as small

as possible, a stipulation that requires a very high

rotational speed.

Depending on the usage, the requirements for

VAD vary; they can be classified by the following

three levels of operations:

Level I: Two-Day Pump

This pump is used mainly after cardiovascular

pulmonary bypass surgery. For this application,

the hemolysis must be kept at a low level.

Approximately 350,000 surgical procedures are

performed each year.

Level 2: Two-Week Pump

This pump is used mainly for postsurgical heart

failure and emergency cases. In addition to the

low hemolysis, low blood clotting is required for

this application. Approximately 25,000 patients

need this treatment each year.

Level 3: Long-Term Pump

The long-term device is needed as a bridge to

transplant or as a permanent assist device. For

this purpose, sustained operation of five years

or longer is desired. Each year approximately

60,000 patients need long-term support, while

only 2000 to 2500 donor hearts are available.

In developing a short-term pump, two major

problems associated with the original design are

related to fluid dynamics: the excessive blood

damage due to high shear stress and the low pumping efficiency, and blood clotting in the bearing

region, which stops the pump after a short period

of operation. To make this design usable, it was

essential to lower the blood damage to an acceptable

level and to increase pumping efficiency so that the

power requirement can be minimized. In addition,

stagnant regions need to be eliminated in the flow

field, especially in the bearing region where blood

clotting prevents the impeller from rotating. To

complete the design effort, it was essential to

quantify the flow characteristics under various

combinations of geometry and operating conditions.

The JSC/DeBakey design team requested that Ames

Research Center (ARC) implement computational

fluid dynamics (CFD) technology to analyze the

flow in the device. NASA/ARC has been leading the

development of CFD tools for incompressible flows

for rocket propulsion and low-speed aerodynamic

flow analysis. This technology is most suitable for

analyzing the flow in VAD.

An extensive computational analysis resulted in

numerous design modifications. A new idea of

including an inducer between the flow straightener

and the impeller was introduced, an idea that came

directly from the work performed in conjunction with

the next-generation liquid rocket propulsion system

development with NASA's Marshal Space Flight

Center. Although the inducer concept is being used

in rocket engines, this is the first time an inducer was

introduced in VAD.

33
Numerousdesignimprovementsweremade

throughtheuseof CFDresultsoncomponentssuchas

bladeshape,inducergap,bladelean,andtaperedhub

step.An ll-day testwascompletedusingthenewest

geometry.Thistestshowedthatnoclottingoccurred

in thebearingregionbetweentheimpellerandthe

diffuser.Thefinaldesignhaspassedthetwo-week

requirements.

DuringFY97,arepresentativeunsteadyflow

profilefromheartexitwasgivenasaninflowtothe

inletcannulato theVAD.Theresultshavebeen

analyzedtodeterminebenefitsofdevelopingan

adaptivecontrolmechanism.

Significance of the results

The current design is compact and provides patient

mobility. The major bottleneck has been the excessive

thrombus and blood damage. The current effort

resulted in the present design, which eliminates those

problems and enables the device to be practically

usable. An additional unsteady control mechanism

will enhance patient mobility.

Publications resulting from the study

Kiris, C.; Kwak, D.; and Benkowski, R.:

Incompressible Navier-Stokes Calculations

for the Development of a Left Ventricular

Assist Device. Accepted for publication in

Computers and Fluids, 1997.

Kiris, C.; Kwak, D.; and Benkowski, R.:

Computational Flow Analysis of a Left

Ventricular Assist Device. Submitted to

J. Artificial Organs.

Keywords

Biofluid computation, Ventricular assist device

34
Demonstration of a 7 Kelvin Pulse Tube Cooler Using

Rare Earth Regenerators

Investigator(s)

Jeffrey M. Lee, Ames Research Center,

Moffett Field, CA 94035-1000

Other personnel involved

Peter Kittel, Ames Research Center

Objectives of the study

To investigate and demonstrate a 7 K pulse tube

cooler using rare earths as the regenerator material.

Two coolers will be examined. The first will be

tested using erbium-3-nickel (Er3Ni) in the form of

small-sized spheres (250%tm diameter) and the

second will use neodymium (Nd)-stacked plates that

are 150%tm thick and spaced 25 _m apart. These

materials possess relatively high heat capacity at

these low temperatures over existing lead regenerators. The increased heat capacity will lead to betterperforming pulse tube coolers.

Progress and results

Preparation work for the demonstration is complete.

The optimum sphere size, plate size, and plate

spacing were calculated using a linearized, twodimensional pulse tube model developed at Ames.

The Er3Ni spheres have been ordered. The Naval

Surface Warfare Center, which is involved in

fabricating Nd regenerators for low temperature

coolers, has encouraged the present design and has

recommended a source for fabricating the plates.

The required instrumentation and data acquisition

systems have been ordered. Last, a computational

fluid dynamics (CFD) study has begun to further

examine whether laminar or turbulent flow is better

for these regenerators.

Significance of the results

This technology demonstration of the 7 K pulse tube

will be important for future missions, such as to

Mars, where the liquefaction of hydrogen will be

required for fuel for returning to Earth.

Keywords

Pulse tube, Cryocooler, Regenerator

35
Wireless Video Measurements of Rotor Blade

Displacement and Deformation

Investigator(s)

Douglas L. Lillie, Ames Research Center,

Moffett Field, CA 94034-1000

Alan J. Wadcock, Sterling Software Systems,

Ames Research Center

Objectives of the study

To demonstrate a portable system for the measurement of rotor blade displacement and deformation.

Portability describes the self-contained nature of the

proposed system, which requires ZERO slip ring

channels for either signal transmission or power

supply.

Progress and results

The following equipment has been procured:

• 200-MHz dual Pentium processor

• wireless video system for telemetry of the video

signal from the hub-mounted video camera

• National Instruments frame grabber board and

image acquisition software.

Operation of the image acquisition board has

been verified at the required frame rates. In addition, researchers attended training classes on the

NASA/High Technology Corporation secondgeneration Video Model Deformation System. This

model deformation system developed at NASA

Langley Research Center will be the backbone of the

image-processing system.

Keywords

Rotor, Displacement, Video

36
Validation of a Nose-Channel Concept for Supersonic

Drag Reduction

Investigator(s)

Mark E. Newfield, Ames Research Center,

Moffett Field, CA 94035-1000

Stephen M. Ruffin, Georgia Institute of

Technology, Atlanta, GA 30332

Objectives of the study

To conduct an experimental proof-of-concept study

to validate the computationally predicted drag

reduction at supersonic speeds for a body with a

hollow channel extending from the nose to the

trailing edge. This objective is being accomplished

by measuring the lift and drag performance (from

time of arrival and shadowgraph image trajectory

analysis) of conventional and channeled axisymmetric sphere/cone models flying in the Ames

Ballistic Range.

Progress and results

Significant progress has been made in establishing the viability of the nose-channel concept as an

effective drag reduction technique. Navier-Stokes

simulations of airfoils and axisymmetric bodies

with and without channels indicate that the nosechannel concept significantly reduces total drag

and increases the Lift/drag. A reduction in sonic

boom signature was also predicted. Experimental

channeled and conventional models have been

designed and fabricated, and will be tested in the

Ames Ballistic Range at Math 2.5. As shown in

figure 1, pretest computational comparisons predict

an 11-percent drag reduction, and a 60-percent

increase in lift/drag from the nose-channel concept

model.

The nose-channel concept has potential for

high payoff. For planetary-entry, hypersonic, and

supersonic-cruise vehicles, drag reduction and

increased lift/drag can lead to greater range capability, increased payload mass fraction, improved fuel

efficiency, and enhanced maneuverability. The

channel concept is potentially useful in drag and

sonic boom signature reduction applications.

The next phase of the investigation will focus on

making high-fidelity measurements of lift and drag

versus angle of attack from trajectory analysis of

Ballistic Range sphere/cone nose-channel concept

models. Concurrently, sonic boom pressure signature measurements will also be made to validate

predicted reductions for nose-channel configurations. Computational and experimental investigations of more complicated three-dimensional (3-D)

bodies will also be explored.

Publications resulting from the study

Ruffin, S. M.; and Gupta, A.: Supersonic ChannelAirfoils for Reduced Drag. AIAA Paper 97-0517,

Jan. 1997.

Keywords

Drag, Lift/drag ratio, Channel

,Mach 25 Alpha = 5 @a+g,, Pressure = : a_m, Temperalu:e = 298K

No+Chanter Ro+utl$:

c = 06Z,_

No_+¢-C ha nr'_q molul+,l :

42,5% L_,_ _crel_e

59.7% I-_ _r_rQm++

!

Figure 1. Computational fluid dynamics (CFD )

simulations---experimental models.

37
Simulation Modeling Investigations of the Terrestrial

Carbon Cycle

Investigator(s)

Christopher Potter, Ames Research Center,

Moffett Field, CA 94035-1000

Other personnel involved

Steven Klooster, California State University,

Monterey Bay, Monterey, CA 93955

Vanessa Brooks, Johnson Controls World

Services, Ames Research Center

Objectives of the study

To overcome most of the significant technical

obstacles to development of a computing and

visualization framework that will help in coupling

and testing model algorithms of physical and

biogeochemical controllers on carbon trace gas

emissions from a dynamic global land surface

simulation.

Progress and results

A prototype model design that uses data collected

at various validation sites located throughout the

terrestrial biosphere is now in test phase. This

dynamic global vegetation model (DGVM) is being

closely coupled to the NASA--Carnegie-AmesStanford Approach (CASA) trace gas model of

Potter and Klooster (ref. 1), which includes calibration of seasonal phenology algorithms using

global satellite data. The coupled DGVM design is

based conceptually on two main elements of

Tilman's (1985) resource-ratio hypothesis of vegetation change: (1) plant competition for resources

(water and light) over relatively short time periods

of months and seasons; and (2) the long-term pattern

in the supply of growth-limiting resources such as

water and nutrients; i.e., the resource-supply

trajectory.

Significance of the results

When completed, this dynamic ecosystem model,

which will run on a regional or global grid structure,

will help enable scientific investigations of transient

biosphere interactions with atmospheric chemistry

and climate on a planetary scale. It will be among

the first ecosystem models to include processoriented controls over global hydrologic, energy,

and ecosystem trace gas exchange with a changing

land surface. This general outcome is a crucial

element of the Strategic Plan for NASA's Mission to

Planet Earth (MTPE).

Publications resulting from the study

An article has been submitted to the Ecological Soc.

of Am. Bull. (Number 78).

Reference

Potter, C. S.; and Klooster, S. A.: Global Model

Estimates of Carbon and Nitrogen Storage

in Litter and Soil Pools: Response to

Changes in Vegetation Quality and Biomass

Allocation. Tellus Series B---Chemical and

Physical Meteorology, vol. 49, no. 1,

Feb. 1997, pp. 1-17.

Keywords

Carbon cycle, Ecosystem modeling, Climate change

38
Adaptation of Bone to Mechanical Stimulation:

Development and Characterization of a Unique Osteoblast

Loading System

Investigator(s)

Nancy D. Searby, Emily Morey-Holton, and

Ruth Globus, Ames Research Center, Moffett

Field, CA 94035-1000

Ekhson Holmuhamedov, Mayo Clinic,

200 First St. SW, Rochester, MN 55905

Other personnel involved

Conrad Macy, Lockheed Martin Engineering

and Sciences Company, Ames Research Center

Harry Yee, University of California,

San Francisco, CA 94143

Objectives of the study

1) To develop a cell loading system for investigation

of the biochemical and structural response of cells to

cyclic mechanical loading. The cell loading system

will (a) load each cell uniformly and physiologically;

(b) dynamically load cells with cyclic tensile and

compressive mechanical deformation; (c) apply

shear stress to cells via fluid flow; and (d) permit

real-time microscopic observations of the ceils at a

single set-point in each loading cycle.

2) To perform scientific characterization tests

demonstrating that the loading system will support

the intended science. Engineering tests will confirm

load uniformity and reproducibility. Biological tests

using rat osteoblasts, or bone forming cells, will

include measurements of cell shape, orientation,

differentiation, and maturation. Immunofluorescence localization of cytoskeletal and

extracellular matrix components will demonstrate

that the required features of cellular and extracellular structure can be imaged in cells grown in the

loading system.

3) To develop a model based on structural

analyses to predict changes in the cell shape, orientation, and structure, depending on the applied load.

Three-dimensional cell shapes will be measured

using nonpenetrating fluorescent dyes, and

combined with data from Objective 2 to support

model development.

Progress and results

The loading system has been designed that will load

the ceils uniformly and physiologically with cyclic

tensile and compressive mechanical deformation,

and will permit real-time microscopic observations

of the cells at a single set-point in each loading cycle.

A prototype apparatus has been constructed, and

biocompatibility of cell chamber materials has been

demonstrated. Compatibility of celt chamber

materials with both real-time phase contrast

microscopy and fixed cell immunocytochemistry has

been tested. The cell chamber design has evolved,

chamber prototypes have been built and tested, and

a final design for mechanical deformation studies

has been selected. Biocompatibility tests in the cell

chambers showed that osteoblasts differentiated

normally and produced bone nodules. The loading

frame and drive system have been designed and

integrated with the cell chambers and a computer

control system. Initial engineering load uniformity

tests have been completed. Tests of cells in the

integrated loading system are in progress.

Cytoskeletal and extracellular matrix proteins in

osteoblasts have been localized in control, stationary

cultures using immunocytochemistry techniques,

and cell orientation has been determined using

phase microscopy.

Significance of the results

A unique system has been developed that will

permit the investigation of the effects of physiological levels of mechanical loads on the morphology

and function of osteoblasts. Completion of the

science investigations will determine the role of the

osteoblast's cytoskeleton and attachments to the

extracellular matrix in responding to mechanical

loads. Determination of the mechanisms that

osteoblasts use to respond to mechanical loading

will lead to a better understanding of the role

osteoblasts play in situ in bone as they adapt bone

structure in response to daily mechanical loads

generated by physical activities, such as walking, or

reduced activity, as seen in spaceflight. In addition,

the loading system has broader applications,

including determining the response to mechanical

39
stimulation of other cell types, such as osteoclasts,

osteocytes, endothelial, and muscle cells.

Keywords

Mechanical loading, Osteoblast, Mechanical strain

4O
Dexterous Walking for Mobility in Unstructured Terrain

Investigator(s)

Michael Sims, David Wettergreen, and

Hans Thomas, Ames Research Center,

Moffett Field, CA 94035-1000

John Bares and Dimitrious Apostolopolous,

Carnegie Mellon University, 5000 Forbes Ave.,

Pittsburgh, PA 15213

Objectives of the study

To develop gait planning and control for highdegree-of-freedom, walking robots with application

to locomotion in unstructured, rough terrain. This

effort will develop new control techniques for

dexterous walking and mobility, with an emphasis

on behavior- and neural-based methods. In addition,

these control techniques will allow the integration

with reactive and deliberative control methodologies. To support development of these new algorithms, both a virtual environment simulator and

a walking mechanism hardware testbed will be

developed to demonstrate rough-terrain locomotion.

Progress and results

The hardware, software, and programmatic infrastructure has been built. The basic electrical and

mechanical design for the walking robot testbed has

been developed, and detailed mechanical design for

the legs has begun. The virtual environment

simulator is being developed.

The basic walking chassis under development is

a radially symmetric hexapod with orthogonal legs

(fig. 1). This leg/body configuration allows the

unconstrained body translation regardless of yaw.

Each leg comprises three degrees of freedom: a

rotary hip, a prismatic knee, and a prismatic foot.

The hip and knee joints operate in the horizontal

plane, while the foot operates in the vertical plane.

This leg configuration decouples horizontal and

vertical body motion, minimizing the overall energy

consumed by locomotion, since support can be

achieved via mechanical braking of the vertical

actuator. The necessary motors and control

amplifiers for all six legs have been purchased.

The control system of the walking robot testbed

allows for hybrid torque-position control over all

18 degrees of freedom in the walking robot. Joint

feedback is generated by joint position sensors

(potentiometers), semiconductor strain gauges, and

contact switches in the foot. In addition, attitude

feedback is generated by a compass-inclinometer.

The control system consists of a 68060 processor

with 20 12-bit analog output channels, 56 12-bit

analog input channels, and 40 digital channels.

Analog inputs are used to measure strain gauge and

potentiometer signals, and analog output is used to

drive pulse-width modulated (PWM) amplifiers,

which in turn drive the motors.

The control system of the walker has been

integrated with a graphical, virtual environment

simulator, which simulates the inputs from feedback

sensors and the joint responses and allows highlevel planning algorithms to be tested. The simulator

is implemented on an SGI workstation using the

VEVI software package.

Significance of the results

The ability to locomote efficiently and autonomously on harsh planetary surfaces is a key requirement for the exploration of the solar system. The

results to date will allow development and evaluation of advanced gait control algorithms, making

walking a viable locomotion technique for NASA

missions. In addition, the mechanical configuration

being developed is optimized around power

consumption and maneuverability, key factors in

the design of surface exploration systems.

Keywords

Legged locomotion, Walking, Planning, Robot

navigation, Planetary rovers

Figure 1. Omnidirectional hexapod.

41
The Origin and Control of 3-D Phenomena in Nominally

2-D Flows

Investigator(s)

Murray Tobak, Ames Research Center,

Moffett Field, CA 94035-1000

Jonathan H. Watmuff, MCAT Institute, Ames

Research Center

Objectives of the study

Observation of nominally two-dimensional (2-D)

(including axisymmetric) flows reveals an almost

universal tendency to develop localized threedimensional (3-D) phenomena that can dominate

the behavior of the flow. Laminar flows are specially

susceptible to this tendency. Accurate, experimentally verified computation of this type of behavior

has not been demonstrated, for even the simplest of

flows; e.g., prediction of transition to turbulent flow

is notoriously inaccurate.

The prevailing view is that the final stage of

transition involves the onset of 3-D characteristics in

2-D Tollmien-Schlichting (TS) waves that originate

upstream. Considerable effort has been devoted to

studying the nonlinear development of TS waves in

an effort to identify the origin of the 3-D developments. However, there is evidence to suggest that

other phenomena, which are unrelated to TS waves,

may play a potentially more significant role in

promoting 3-D effects. These phenomena have been

largely overlooked.

The most clearly evident phenomena are weak

streamwise vortices (also known as Klebanoff

modes) that introduce spanwise variations of the

boundary layer thickness.

The objectives of this study are:

1. To gain a fundamental understanding of the

underlying physical processes leading to the

formation of streamwise vortices in nominally

2-D stagnation flows.

2. To explore the role of local pressure gradient as

a parameter for controlling the subsequent

development of streamwise vortices as the

leading edge flow is blended into a 2-D flat-plate

zero pressure gradient (ZPG) Blasius boundary

layer.

3. To explore the stability characteristics (e.g.,

growth rate) of streamwise vortices in a Blasius

boundary layer.

4. To explore conditions under which interactions

between the vortices and other disturbances

(e.g., TS waves) are favorable (e.g., suppression

of TS wave growth) or detrimental (e.g., secondary instabilities associated with the vortices).

5. To develop more sophisticated methods for

quantifying wind tunnel flow quality.

Progress and results

The experiments are performed in a dedicated,

small-scale, standalone wind tunnel with a highly

uniform free stream (_U/U 1 < 0.05 percent) and

an extremely low background disturbance level

(u/U1 < 0.05 percent). (U is the streamwise component of the temporal mean velocity, u is the root

mean square of the streamwise velocity of fluctuations, and the subscript 1 refers to free stream.)

Detailed measurements are made in a Blasius

boundary layer with an exceptionally low background disturbance level (u/U1 < 0.08 percent for

Re = 0.7 x 106) and with a high degree of spanwise

uniformity.

The wake behind a fine wire has been explored

as a means of deliberately introducing a small nonuniformity into the mean flow for the purpose of

stimulating the formation of streamwise vortices

in the boundary layer. The technique consists of

stretching a fine wire normal to the flow and normal

to the leading edge some distance upstream. Two

wire diameters are used; i.e., d = 25 _m (0.001 inch),

corresponding to Reynolds numbers based on the

wire diameters of Ra = 16.7 and Rd = 33.4, respectively. The strength of the wake behind the wires

ranges from I to 3 percent of the free-stream

velocity.

Interaction of wake behind the wire with the

leading edge leads to the formation of a pair of weak

streamwise vortices in the boundary layer. The

vortices are associated with local regions of elevated

unsteadiness that occur at frequencies very much

lower than the instabilities predicted from linear

stability theory. The vortices are also associated with

a local increase in the thickness of the boundary

layer.

The most recent results are remarkable since

they demonstrate the formation of vortices in the

layer, even when the d = 50 _tm wire is located

42
diametersupstreamoftheleadingedge(i.e.,

upstreamofthecontraction)andthestrengthofthe

wakeislessthan0.02percentof thefree-stream

velocity.

Significance of the results

The association of premature transition to turbulence with free-stream nonuniformity has important

implications for wind tunnel model tests and the

issue of flow quality.

The detrimental effect of the vortices is demonstrated by showing that the growth of TS waves is

more rapid in the local region of increased boundary

layer thickness between the vortices. The increased

growth rate ultimately leads to premature transition

to turbulence farther downstream.

Publications resulting from the study

Watmuff, Jonathan H.: Advanced Flow Diagnostics

for Laminar Flow Control and Low Disturbance Facilities. MCATInst. Progress

Report for Performance Period 11/1/95 to

10/31/96. Contract NAS2-14109, Task

Number 5, October 1996.

Watmuff, Jonathan H.: Interactions between

Klebanoff Modes and TS Waves in a Blasius

Boundary Layer. AIAA Paper 97-0558,

presented at the 35th AIAA Aerospace

Sciences Meeting and Exhibit, Reno, Nev.,

Jan. 6-10, 1997.

Tobak, M.: Topologically Derived Separation Onset

Conditions for Two- and Three-Dimensional

Laminar Flows. AIAA Paper 97-0866,

presented at the 35th AIAA Aerospace

Sciences Meeting and Exhibit, Reno, Nev.,

Jan. 6-10, 1997.

Watmuff, Jonathan H.: Detrimental Effects of

Almost Immeasurably Small Free-Stream

Nonuniformities Generated by Wind Tunnel

Screens. ALAA Paper 97-0228, presented at

the 35th AJAA Aerospace Sciences Meeting

and Exhibit, Reno, Nev., Jan. 6--10, 1997.

Watmuff, Jonathan H.; and Tobak, M.: Flow Quality

and Boundary Layer Transition. Bull. Am.

Phys. Soc., 1997 (to appear).

Keywords

Streamwise vortices, Tollmien-Schlichting waves,

Flow quality

43
Super Low Thermal Conductivity and Low-Density

Ablative Composites

Investigator(s)

Huy Tran and Christine Johnson,

Ames Research Center,

Moffett Field, CA 94035-1000

Objectives of the study

To demonstrate the feasibility of chemically

combining aerogel technology with the latest Lightweight ceramic ablator material to produce an

ultra_low thermal conductive in-depth material with

high ablative performance at the outer surface. This

objective is being accomplished by integrating the

aerogel material for its super Lr_ulative properties

and different light ceramic ablators material for their

ablative characteristics.

Progress and results

Samples of aerogel material obtained from the

Lawrence-Livermore National Laboratory (LLNL)

were successfully bonded on the phenolic impregnated carbon ablator (PICA) without difficulty.

Thermal conductivity of the system is being measured as a function of temperatures and pressures.

Keywords

Aerogel, Ablative materials, Planetary entry, Heat

shield, Thermal protection system (TPS)

iii!iii!i! ii!_!i!!! i_ ......

44
A Deployable Vortex Diffuser for Reducing Blade-Vortex

Interaction Noise

Investigator(s)

Chee Tung and Ken McAlister, Ames Research

Center, Moffett Field, CA 94035-1000

Objectives of the study

To change the structure of the trailing vortex of

helicopter rotor blades by reducing the magnitude

of its peak velocity. The civilian helicopter fleet

cannot reach full potential because of the noise level

during descent into heliports near communities.

Much of the noise comes from rotor blades cutting

through their own wake--a phenomenon referred to

as blade-vortex interaction (BVI) noise.

Particle Trace (Clean Rotor, Top View)

[

J I

'_,e L

root

tip

i.e.

\

Progress and results

The computational fluid dynamics (CFD) solutions

of a candidate trailing-edge spoiler have been

completed.

Significance of the results

The peak velocity of the trailing vortex has been

reduced by 30 percent. The particle traces in the

figures show that the vortex structure has been

altered by the trailing-edge spoiler.

Keywords

Rotor wake, Blade/vortex interaction, Deployable

spoiler

Particle Trace (Spoiler #3, Top View)

1 Direction of

// Rotation

,_"

f

1.e.

tip

\

i.e.

root /

\

45
Adaptation to Virtual Gravitational Environments

Investigator(s)

Robert B. Welch, Ames Research Center,

Moffett Field, CA 94035-1000

Michael Aratow, Ames Research Center

Associate

Robert Whalen, Ames Research Center

Wanda L. Boda, Sonoma State University,

Sonoma, CA 95476

Alan Hargens, University of California,

San Diego, Ames Research Center

of lower body positive pressure and a computergenerated virtual environment with which the

subject interacts by means of a motor-driven treadmill on which he/she walks; and (2) demonstrate

that human beings are able to adapt their walking

behavior to this simulation while simultaneously

maintaining their ability to walk in the normal (l-g)

environment.

Keywords

Preflight adaptation training, Mars, Reduced gravity

Objectives of the study

To (1) simulate many of the bodily and visual effects

of ambulating on Mars by means of a combination

46
Fastenerless Structural Connections for Tiltrotor Aircraft

Investigator(s)

John Zuk, Ames Research Center,

Moffett Field, CA 94035-1000

Clem Hiel, W. B. Goldsworthy & Assoc., Inc.,

23930-40 Madison St., Torrance, CA 90505

Objectives of the study

To conduct innovative research leading to the

development of a new class of fastenerless connections, called "snap joints," for assembly of composite

structures, with special emphasis on tiltrotor

aircraft.

Progress and results

Ideas for snap joints have been formulated.

Conceptual designs utilizing computer-aided design

(CAD) have been developed, and candidate test

specimens have been fabricated and developed.

A full-scale generic snap joint illustrating ease of

assembly and positive interlocking features has been

fabricated.

A new snap joint filter architecture has been

fabricated and tested; results were compared with a

current state-of-the-art laminated fiber architecture.

Significance of the results

The new snap joint architecture increased the

interlaminar shear strength by at least a factor of

five. Plans include a patent application and an

industrial partnership.

Keywords

Composites, Snap joints

47

Appendix A-1

Final Reports

Title of Investigation

Software Interface Analysis Tool (SIAT)

Investigator(s) (show affiliation)

John C. Hinkle, NASA Software IV&V Facility; Steven Easterbrook, West Virginia Univ.; Randy Hefner, Intermetrics

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

0

$40,000 (Intermetrics, Inc.)

0

Expected completion date 9/30/97

Authorized in FY 97 $40,000

Requested for FY

(If any)

rx---l Completed in FY 1---] Continued in FY

If continued in FY __ ['-] With funds remaining? _] With FY funds?

If transitioned to other funding, to RTOP (number?) ARCO5N UPN 323-08

to Program (name?)

to Other (identify)

Purpose of investigation

To improve effectiveness, productivity, and quality of external interface source code analysis for large, complex, distributed

systems being developed in the Ada programming language.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

The SIATphase 1 prototype has been demonstrated and is planned for utilization on the International Space Station (ISS)

Independent Verification and Validation (IV&V) contract. It has already been deployed at the NASA Software IV&V Facility in

Fairmont, West Virginia, and is soon to be deployed at the IV&V site in Houston, Texas.

Planned future work

SIAT phase 2 development has been awarded under Center Initiative number ARC05N.

Prepared by Org. Code M/S ! Phone

IT John C. Hinkle

ARC 735 (Sep 97)E Previous editions are obsolete

(304) 367-8205
DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

The Development of a Micromachined Gas Chromatography System for Future Planetary Missions

Fiscal Year

1997

Investigator(s) (show affiliation)

Daniel R. Kojiro, ARC; Thomas C. Shen, SETI Institute, ARC; James T. Suminto, MicroTech Scientific, Inc.

Funding

Year Initiated FY95

Total priorto FY 97 $40,000

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$21,000

$19.000 (MicroTech Scientific, Inc.)

I--'] Completed in FY

If continued in FY 98 l_ With funds remaining?

If transitioned to other funding, to RTOP (number?) 344-36-20-24

to Program (name?)

to Other (identify)

Expected completion date 9/30/97

Authorized in FY 97 $40,000

Requested forFY 98

(If any)

[] Continued in FY 98

i--i With FY funds?

Planetary Instrument Definition and Development Program

Purpose of investigation

To develop lightweight, low-power, micromachined, gas chromatographic equipment for future planetary atmospheric probes and

soil gas or pyrolytic analysis. A gas chromatography (GC) instrument was used for the Pioneer Venus mission. However, future

missions, such as the Mars Exploration Missions, discover missions, and missions to probe outer planet atmospheres or outer planet

moons, will require further reduction in weight, volume, and power requirements.

FY 96 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Received 1996 Planetary Instrument Definition and Development Program (PIDDP) award for continued R&D support.

Planned future work

Future work plan has been developed and described in the PIDDP proposal.

Prepared by

Thomas C. Shen

ARC 735 (Sep 97)E Previous editions are obsolete

I Org. Code M/S

SSX 239-12

Phone

(650) 604-5769
j_l_,_Am es

l_i_,r_iJ Research

_Center

Title of Investigation

Planetary Wind Sensor

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Paul Kolodziej and Louis J. Salerno, ARC; David W. Bogdanoff, Thermosciences Institute; Gregory Wilson, Arizona State Univ.

Funding

Yearlnitiated FY 96 Expected completion date 9/30/97

Total priorto FY 97 $40,000 Authorized in FY 97 $40,000

Total expended in FY 96

In-house

(Estimated) Requested for FY__

(If any)

$25,000

Contracts (identify) $I5,000 (Thermosciences Institute)

Grants (identify)

Status of Study

r_ completed inFY 97 r-] continued in FY

If continued in FY [_] With funds remaining? [_ With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To accurately measure wind velocities in a low-density environment such as the Martian atmosphere (approximately 6 mbar). The

objective is to develop a low-power, lightweight, reliable, and cost-effective means of sensing wind speeds and direction for current

and future planetary exploration programs. This objective is being accomplished by modification of an existing, commercially

available wind speed and direction sensor that employs ultrasonic transducers as sensing elements.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Measurements were made in the Ames Aeolian Research Facility at reduced pressures. A commercially available sensor employing

ultrasonic transducers successfully operated down to 110 mbar.

Planned future work

To improve the sensitivity of the sensor further, a novel concept employing a spark generator in conjunction with ultrasonic

piezoelectric transducers is expected to extend the usable range of the sensor to measurement of wind velocities at pressures down

to 6 mbar or less, while maintaining low cost, simplicity, and reliability.

Prepared by Org. Code M/S Phone

Louis J. Salerno STM 234-1 _(650) 604-3189 i

ARC 735 (Sep 97)E Previous editions are obsolete
DIRECTOR'S DISCRETIONARY Fiscal Year

FUND REPORT 1997

Title of Investigation

Quantitative Characterization of Porous TPS Microstructures Using Laser Scanning Confocal Microscopy

Investigator(s) (show affiliation)

Frank Milos, ARC; Jochen Marschall, Eloret Institute; Joanne Frerich, Sandia National Laboratories

Funding

Yearlnitiated FY96 Expected completion date 9/30/97

Total priorto FY 97 $40,000 Authorized in FY 97 $40,000

Total expended in FY 97 (Estimated) Requested for FY 98 0

(If any)

In-house $20,000

Contracts (identify)

Grants (identify)

$20,000 (Sandia National Labs*)

'Status of Study

[] Completed inFY 97 [-7 Continued in FY

If continued in FY 98 I--] With funds remaining? r--i With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To explore the capability of laser scanning confocal microscopy (LSCM) to provide quantitative information about the porous

microstructure of various thermal protection system (TPS) materials. The idea is to use LSCM to obtain digitally stored

representations of the pore structure and to devise computational algorithms to extract numerical values for such quantities as

porosity, surface area per volume, pore size and orientation distributions, etc. This information will then be incorporated into

various modeling efforts, such as, e.g., internal radiation transport and gas flow in fibrous insulations.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Preliminary results from this work were presented at the Workshop on Thermalphysical Phenomena in Microscale Sensors,

Devices, and Structures, Baltimore, Maryland, Aug. 1997. Further publication and presentation of the results are anticipated.

Planned future work

A manuscript that details the application of LSCM to obtain quantitative microstructural information on highly porous fibrous

materials is being prepared.

A study to compare experimental permeability measurements with LSCM-based model computations of permeability will be

concluded. It is anticipated that the results of this study will be presented or published.

*Purchase Order No. A49107D (SLS)

Prepared by

Jochen Marschall

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

i STM 234-1 (650) 604-0829
i[_.,_Ames

l,i_,._J Research

"v"_llV Center

Title of Investigation

NASA Ames Astrobiology Academy

DIRECTOR'S DISCRETIONARY Fiscal Year

FUND REPORT 1997

Investigator(s) (show affiliation)

Douglas A. O'Handley, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

If continued in FY

(Estimated)

$66,000 (Lockheed Martin Missiles & Space)

Expected completion date

Authorized in FY

Requested for FY

(If any)

[] Completed in FY 97

[] With funds remaining?

9/30/97

97 $66,000

If transitioned to other funding, to RTOP (number?)

to Program (name?) Astrobiology

to Other (identify)

[-7 Continued in FY

[] With FY funds?

Purpose of investigation

To help guide future leaders of the U.S. Space Program by giving them a glimpse of how NASA operates. Applicants are chosen

for this summer institute for their scientific accomplishments, scholarly achievement, and individuality. Another goal is to provide

insight into all the elements that make the NASA missions possible, while at the same time assigning the student to one of NASA's

best researchers to contribute toward one of its missions.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

The efforts of one student are expected to lead to a publication in the scientific literature: Ross, Muriel; and Hand, Kevin:

Biocomputation: 3-D Visualization of Adaptive Changes in Gravity Sensors in the Space Environment.

Planned future work

As a result of the success of the first Ames Astrobiology Academy, we are planning to host another Academy in 1998. The

Academy will be expanded to accommodate 15 students, and will thus allow greater participation with Ames principal

investigators. This program will evolve continually. It is expected that Kennedy Space Center will be the fifth NASA Center

to host students in this manner.

Prepared by

Douglas A. O'Handley

ARC 735 (Sep 97)E Previous editions are obsolete

, I

Org. Code M/S ' Phone

SS 245-1 (650) 604-3525
__+,_Ames

+_7__-_J Research

,_DY Center

Title of Investigation

Does Ultraviolet Radiation Affect Carbon Isotope Fractionation?

DIRECTOR'S DISCRETIONARY

FUND REPORT I Fiscal 1997Year

Investigator(s) (show affiliation)

Lynn Rothschild, David Des Marais, ARC; Aruna Balakrishnan, student programs; Anne Tharpe, ManTech Systems Engrg. Corp.

Funding

Yearlnitiated FY96 Expected completion date 9/30/97

Total priorto FY 97 $40,000 Authorized in FY 97 $40,000

Total expended in FY 97 (Estimated) Requested for FY 98 0

(If any)

In-house $40,000

Contracts (identify)

Grants (identify)

Status of Study

rx----]Completed in FY 97 [-7 Continued in FY 98

If continued in FY 98 [--] Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To determine if ultraviolet (UV) radiation affects stable carbon isotope ratios. If so, is there an ecologic (e.g., microbial mat vs.

phytoplankton) or taxonomic (e.g, prokaryote vs. eukaryote, alga vs. plant) correlation with the effect? These data will provide the

basis to present the phenomenon to the scientific community, to estimate how widespread the phenomenon is, and to suggest ways

to begin to elucidate the mechanisms underlying the effect. Ultimately this work could lead to a re-interpretation of isotopic ratio

studies, including a re-interpretation of the fossil record.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Data on the isotopic effect of UV radiation were presented at the IAI Workshop on UV in the Marine Environment in Baja, Mexico.

Planned future work

Prepared by t Org. Code M/S Phone

SGE i 239-12 (650) 604-6525

I I

,Lynn Rothschild

ARC 735 (Sep 97)E Previous editions are obsolete
DIRECTOR'S DISCRETIONARY Fiscal Year

FUND REPORT 1997

Title of Investigation

Use of Evolving Microbial Systems as a Domain for Development of Autonomous Artificial Intelligence Software

Investigator(s) (show affiliation)

David Thompson, ARC; P. Robinson, Caelum-Recom Tech., ARC; R. Mancinelli, D. Smernoff, M. White, SETI Inst., ARC

Funding

Year Initiated FY95 Expected completion date 9/30/97

Total prior to FY 97 $40,000 Authorized in FY 98

Total expended in FY 97

In-house

(Estimated) Requested for FY 98

(If any)

$40,000

Contracts (identify)

Grants (identify)

Status of Study

I_ Completed in FY 97 [--] Continued in FY 98

If continued in FY 98 I---] With funds remaining? [--] With FY 97 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To achieve advances in artificial intelligence (AI)-based software technology for control, diagnosis, and repair of complex

microbial experimental systems, and to gain a better understanding of the role that nitrogen-fixing and denitrifying microbial

systems play in nutrient cycling, atmospheric evolution, and biogeochemical (BGC)cycles on Earth.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Smernoff, D. T.; and Mancinelli, R. M.: Co-organizers of a Half-Day Symposium on the Bioreactor System, in the 1998

International Society for Ecological Modeling Program "Issues in Trophic Systems Synthesis," Ecol. monographs, 1998 (in

preparation).

Robinson, Peter: Autonomous Design and Execution of Process Controllers for Untended Scientific Instruments, Proceedings of

the 1997 1st International Conference on Autonomous Agents, Marina del Rey, Calif., Feb. 5-8, 1997, ACM SIGART,

New York, N.Y., pp. 546-547.

Planned future work

An integrated hardware and software system will be used for ongoing studies of nutrient cycling mediated by microbes and control

ofdenitrification by microbes in closed systems. Autonomy features will be developed further, and new subsystem controllers

based on quantitative and qualitative system models will be added. Export technologies (denitrification control and autonomy

features) will be applied to advanced life support systems.

Prepared by

David Smernoff/Rocco Mancinelli

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

=SSX 239-I2 (650) 604-1230
j_'_Ames

._Res_arch

Title of Investigation

Modeling High-Energy AerocaptureTrajectories for Outer Planet Orbiter Missions

DIRECTOR'S DISCRETIONARY

FUND REPORT I Fiscal 1997Year

Investigator(s) (show affiliation)

Paul Wercinski, ARC; Periklis Papadopolous, Ethiraj Venkatapathy, Thermosci. Inst.; Y-K. Chen, ARC; Lily Yang, Sterling, ARC

Funding

Year Initiated FY96

Total priorto FY 97 $40,000

Total expended in FY 97

In-house

(Estimated)

Expected completion date 9/30/97

Authorized in FY 97 $40,000

Requested for FY

(If any)

Contracts (identify) $40,000 (Thermosci. Inst., Sterling)

G rants (identify)

Status of Study

[] Completed in FY 97 D Continued in FY

If continued in FY El With funds remaining? [-7 With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

The objectivesof the proposed research are threefold. The first objective is to characterize the static aerodynamic coefficientsof the axisymmetric

biconic shape in realistic flow conditions representative of actual flight trajectory. This would include the lift and drag coefficients of the entry

vehicle at various angles of attack. The second objective is to calculate the heating distribution over the surface of the entry vehicle at various

trajectory points. The last objective is to determine TPS requirements from the coupled heating distributions at several trajectory points. With

this analysis, an attempt to incorporate approximate methods of estimating the heating distribution (and subsequent thermal protection material

requirements) with an actual trajectory simulation will be assessed and performed if appropriate.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

DDF study results will be presented to Outer Planet mission planners at the Jet Propulsion Laboratory in 1998.

Prepared by Org. Code M/S Phone

Paul Wercinski STA _230-2 (650) 604-3157

ARC 735 (Sep 97)E Previous editions are obsolete
Appendix A-2

Ongoing Reports

I Year ]

1997

Title of Investigation

Gas-Phase Spectroscopy of Interstellar PAH Analogs

Investigator(s) (show affiliation)

Lou Allamandola, ARC; Farid Salama, SETI Institute, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97

In-house

(Estimated)

$50,000

Expected completion date 1/1/99

Authorized in FY 97 $50,000

Requested forFY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

Status of Study

r--] completed in FY r_ Continued in FY 98

If continued in FY 98 [--] Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To investigate the potential interrelationship between interstellar polycyclic aromatic hydrocarbons (PAHs) and the carriers of the

diffuse interstellar bands (DIBs). The goal is to measure, for the first time, the gas-phase spectra of selected neutral and ionized

interstellar PAH analogs to allow a decisive test for these species as potential DIB carriers. These goals can be achieved by using

the combined techniques of supersonic free-jet expansion spectroscopy (JES)and laser absorption spectroscopy (LAS).

FY 98 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

A feasibility study of the project has been performed and a new experimental setup for a jet supersonic expansion has been

designed. The optimal characteristics (diameter of the nozzle, size and structure of the expansion chamber, pressure range) have

been calculated for the generation of a supersonic jet with the appropriate temperature for a correct simulation of the diffuse

interstellar medium. The vacuum hardware (expansion chamber and precision manipulators),the pulsed nozzle, and the pumping

stations have been either built and/or ordered.

Planned future work

The supersonic jet expansion chamber will be mounted and the first ultraviolet, visible, and near-infraredspectra of a few selected,

free, molecular PAHs in their neutral and ionized forms will be measured.

Prepared by Org. Code M/S I Phone

Farid Salama SSA I 245-6 (650) 604-3384

ARC 735 (Sep 97)E Previous editions are obsolete
j__.,,_Ames

__-;_iJ Research

"_Y Center

Title of Investigation

Development of a Tethered-Glider Probe-Positioning System for Use in Wind Tunnel Testing

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Dale L. Ashby, ARC; Hiroyuki Kumagai, AerospaceComputing, Inc.

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97 (Estimated)

In-house $7500

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

$27,500 (ACI); $5000 (Calspan)

Status of Study

El Completed in FY I'X-] Continued in FY 98

If continued in FY 98 [--I Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To demonstrate the feasibility of using a tethered glider as a minimally intrusive, probe-positioning system in a wind tunnel

environment. The new probe-positioning system, if successful, would provide a cheaper, more flexible means of conducting flow

surveys with probes such as hot wires or seven-hole probes in a large wind tunnel suchas the National Full-Scale Aerodynamics

Complex (NFAC). The capabilities of an onboard, miniature data acquisition system and a flight-control system will also be

demonstrated. If the tethered glider concept proves feasible, future enhancements to the system will include incorporatinga

propulsion system for increased positioning flexibility.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

The design and analysis of the glider airframe is currently under way. Aerodynamic analysis to design and establish stability

derivatives is being done using PMARC, a potential flow code. The flight-control computer hardware and control servos have been

procured, and flight-control software is being written. The inertial navigation system for determining attitude and position has been

defined and is currently beingprocured. A secondary position and attitude sensing system is being evaluated. The integration of

the miniature data-acquisition system has been completed.

Planned future work

Planned work for FY98 includes construction of the glider and installation of the servos for moving control surfaces. The miniature

data-acquisition system and flight-control system will then be installed in the glider. A flight test will be conducted to verify flight

controls and glider performance. The tether system required for wind tunnel operation will be designed and assembled. The probe

position and attitude determination system will also be completed. The complete probe-positioning system will then be tested in the

NFAC in late FY98 or early FY99.

Prepared by Org.Code I M/S Phone

AAL I 247-2 (650) 604-5047

I

Dale Ashby

ARC 735 (Sep 97)E Previous editions are obsolete
i[_..,,_Ames

_.-_iJ Research

V_IV Center

Title of Investigation

Visual Servo-Control Applied to Mobile Robot Navigation

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

I

Investigator(s) (show affiliation)

Maria Bualat, Hans Thomas, David Wettergreen, Gary Haith, ARC; Matt Deans, Carnegie Mellon Univ.

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$40,000

Expected completion date 5/31/99

Authorized in FY 97 $40,000

Requested forFY 98 $40,000

(If any)

[_ Completed in FY [] Continued in FY 98

If continued in FY 98 _-_ With funds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To develop a visual approach to short-range and terminal mobile robot navigation. Visual servo-control techniques for mobile

robots will be developed; these techniques will be implemented on board under realistic computing and telemetry constraints;

analogous obstacle-avoidance techniques will be developed; performance will be quantified and compared to traditional methods;

and this approach will be demonstrated in realistic field experiments.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

None.

Planned future work

Methods for improving performance will be applied; and the visual servoing technique will be tested using low-mounted, fixed

cameras to simulate conditions for near-term rover missions to Mars.

I ] Phone

I Org. Code M/S

! IC 269-3 (650) 604-4250

I

Prepared by

Maria BualadHans Thomas

ARC 735 (Sep 97)E Previous editions are obsolete
DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Active Control of Instability Waves in a Laminar Boundary Layer

Fiscal Year

1997

Investigator(s) (show affiliation)

Sanford Davis, ARC; Anthony Dietz, MCAT Institute, ARC

Funding

Year Initiated FY97

Total priorto FY 9"7 0

Total expended in FY 9"7

In-house

(Estimated)

$24,000

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

$16,000 (MCAT Institute, ARC)

Status of Study

[] Completed in FY [] Continued in FY 98

If continued in FY [_ With funds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To develop and test an active wave cancellation scheme for boundary layer transition control. The control unit consists of an array

of microphones and speakers mounted in a cavity beneath the surface of a flat plate. Initial development and testing is carried out

with the plate boundary layer excited by artificially generated two- and three-dimensional free-stream disturbances in a low-speed

wind tunnel. These repeatable disturbances provide a known input to the control system, allowing detailed studies of the

cancellation process and optimization of the control algorithms. When a satisfactory control scheme has been developed, it will be

evaluated against random three-dimensional instability wave packets excited by free-stream turbulence.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

None.

Planned future work

Testing and optimization of the control algorithms will continue in the next fiscal year.

Prepared by

Sanford Davis/Anthony Dietz

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code

ADF

M/S

i 260-1

Phone

(650) 604-4137
__..,,,_Ames

_ii_ Research

.v'_l17 Center

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Title of Investigation

The Early History of the Biogeochemical Carbon Cycle Can Be Illuminated by Isotopic Microanalyses of Rocks Using aUV Laser

Investigator(s) (show affiliation)

DavidJ. Des Marais, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97

In-house

Contracts (identify)

Grants (identify)

Statusof Study

(Estimated)

$40,000

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

[] Completed in FY 97

If continued in FY 98 r_ With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

[] Continued in FY 98

With FY 98 funds?

Purpose of investigation

To demonstrate the suitability of an ultraviolet laser to extract carbon from geological samples and fresh organic matter for stable

isotopic analysis. To combine a laser, microscope, sample positioning stage, and sample chamber swept by a gas stream to gather

sample gas. To demonstrate that analyses can be obtained at levels of accuracy and precision required for geochemical

interpretation of the origin of the phases under study. Commercially available components mustbe integrated with a new sample

chamber, and an isotope mass spectrometer system most suitable for the isotopic analysis must be selected.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

The components will be integrated into a complete laser ablation system. The system will be calibrated using standard carbonates

and graphitic carbon. First, measurements of geologic materials will be performed and compared with previous measurements

obtained by whole rock analysis and microdrilling. First attempts will be made to perform microcombustion of organic matter in an

oxygen atmosphere, followed by sweeping the combustion products into the GC-IRMS using a helium stream. The system will be

calibrated for research use.

Prepared by

DavidDes Marais

ARC 735 (Sep 97)E Previous editions are obsolete

' Org. Code M/S Phone

SSX 239-4 (650) 604-3220
Remembering To Do Things in Dynamic Environments

Investigator(s) (show affiliation)

Key Dismukes, Roger Remington, and Maria Stone, ARC

Funding

Year Initiated FY97

Total prior to FY 97 0

Total expendedin FY 97

In-house

(Estimated)

$40,000

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested forFY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

Status of Study

_] Completed in FY [] Continued in FY 98

If continued in FY 98 I--] Withfunds remaining? i-_ With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

Prospective memorydemands arise when one forms an intention to perform an action that must be deferred until later. That

intention must be held in memory. Thus a memory load is created that is subject to forgetting. In fact, numerous instances of

prospective memory errors have been reported in daily life and in safety-critical operations. This investigation examines the nature

of prospective memory in tasks such as those performed by air traffic controllers. It will help elucidate the factors that influence

success or failure in controllers' memory tasks. Knowledge gleaned in this study should enable improvements in controller training

and in task design to reduce errors in prospective memory performance.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

With the experimental paradigm that has been developed, data will be collected on the effect on prospective memory of factors such

as the duration an intention must be retained in memory, the availability and character of cues to remind the subject of the intention

the workload on the ongoing task, and the relation of the prospective task to the ongoing task.

Prepared by Org. Code M/S

Key Dismukes AF 262-4

ARC 735 (Sep 97) E Previous editions are obsolete

Phone

(650) 604-0150
A_JAmes

_._ Research

V"_l _' Center

DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Martian Fossils in the ALH84001 Meteorite: An Independent Assessment of the Evidence

Fiscal Year

1997

Investigator(s) (show affiliation)

Jack D. Farmer and David Blake, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

(Estimated)

$21,000

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

Contracts (identify) $19,000 (SETI)

Grants (identify)

Statusof Study

[--] Completed in FY [] Continued in FY 98

If continued in FY 98 r-] With funds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To re-evaluate the biogenicity of microfossil-like features found in the Martian meteorite, ALH84001, based on detailed comparisons to terrestrial

analogs of known origin. To achieve this goal we seek to: 1) use nutrient limitation methods to derive an empirically based estimate for the lower

size limit achieved by four species of small heterotrophic microbes from hydrothermalenvironments considered good analogs for ALH84001;

2) re-evaluate the biogenicity of features commonly found in terrestrial rocks that have been broadly referred to as "nanobacteria"; 3) document

the effects of contemporaneous mineralization on the fossilization potential of small bacteria, particularly those found in hydrothermal environments; and 4) make direct mineralogical and microstructural comparisons of terrestrial analogs of known origin and the putative nanometer-scale

microfossils of the ALH84001 meteorite.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

1) Complete detailed morphometric comparison of experimental cultures; 2) continue nutrient limitation experiments at levels of I and 0.1 percent

to evaluate the effects of prolonged starvation; 3) undertake a transmission electron microscope study of experimental cultures to obse_'e changes

in internal cell structure under starvation and to compare spore morphologies for each species; 4) induce carbonate precipitation within live

cultures to observe the mechanisms of fossilization at the nanometer scale; 5) make quantitative morphometric comparisons of terrestrial analog

materials and putative microtbssils in ALH84001, and develop an archive of results that identifies reliable criteria for assessing biogenicity of

microfossil-like structures in ancient rock materials; and 6) present resuhsat ALH84001 Meteorite session at Lunar Planetary Science Conference

and prepare a manuscript for publication.

Prepared by ] Org. Code M/S Phone

Jack D. Farmer SSX 239-4 i (650) 604-5748

ARC 735 (Sep 97)E Previous editions are obsolete
AL_,,_Ames

,_rr-_i_ii_ Research

_DY Center

DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Remote Sensing of Aircraft Contrails Using a Field Portable ImagingInterferometer

Fiscal Year

1997

Investigator(s) (show affiliation)

Philip D. Hammer, ARC; William H. Smith, Washington University, St. Louis; Stephen Dunagan and Anthony Strawa, ARC

Funding

Year Initiated FY95

Total priorto FY 97

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

$40,000

(Estimated)

$35,000

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY 98

(If any)

$5000 (Washington U. Consortium)

I_] Completed in FY

If continued in FY 98 [] With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Continued in FY 98

El With FY 98 funds?

Purpose of investigation

To measure visible and infrared radiative effects of aircraft contrails to provide information about their spatial distributions, their

microphysical properties (especially ice crystals), their time evolution, and their surroundings. This objective is being accomplished

by applying a novel remote sensing technique, imaging interferometry, which provides two-dimensional spectral images of contrails

and other atmospheric features of interest.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

An improved digital array scanned interferometry (DASI) sensor is being developed for the near infrared.

Planned future work

To make additional ground-based measurements of aircraft contrails after acquiring a new lens system for the infrared DASI sensor.

The improved infrared instrument will permit obtaining images with good spatial resolution over the entire spectral range of 4000 to

11,000 cm-1 (0.91 to 2.0 microns). The anticipated high-quality measurements will enable completion of the study.

Prepared by

Philip Hammer

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

SGE 242-4 (650) 604-3383
___ .,,_Ames

_iJ Research

+'__' Center

Title of Investigation

A Modeling Approach to Global Land Surface Monitoring with Low-Resolution Satellite Imagery

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Christine A. Hlavka, ARC; Jennifer Dungan, JCWS; Gerry P. Livingston, U. of Vermont

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$30,000

Expected completion date 9/30/98

Authorized in FY 97 $30,000

Requested for FY 98 $30,000

(If any)

[-"] Completed in FY [] Continued in FY 98

If continued in FY 98 r-] Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To develop a new approach to computing accurate estimates of global extents of land use/land cover types with maps derived from

satellite imagery. This objective is being accomplished by: 1) testing models of the size distribution of patches of specific cover

types, as mapped with imagery of relatively fine spatial resolution; and 2) developing numerical procedures for estimating the total

area of these cover types with low resolution satellite imagery that incorporate models of size distribution and effects of pixelation.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Hlavka, C. A.; and Livingston, G. P.: Statistical Models of Fragmented Land Cover and the Effect of Coarse Spatial Resolution on

the Estimation of Area with Satellite Sensor Imagery. International J. Remote Sensing, vol. 18, no. 10, 1997, pp. 2253-2259.

Hlavka, C. A.: Statistical Models of Landscape Pattern and the Effects of Coarse Spatial Resolution on Estimation of Area with

Satellite Imagery. To be published in a book on spatial accuracy, co-edited by H. T. Mowrer and R. G. Congalton, by the Ann

Arbor Press. In review.

Planned future work

Current data analyses will be completed and additional data sets will be analyzed to characterize the distribution of area as a

function of patch size, including maps developed from Radarsat imagery. Simulations of size distributions will be developed and

comparedto those measured on digital maps. Procedures for correcting for pixelation effects and estimating parameters of the

underlying size distribution will be developed and tested.

Prepared by Org. Code M/S Phone

Christine A. Hlavka SGE 242-4 (650) 604-3328

ARC 735 (Sep 97)E Previous editions are obsolete
A_..,,_Ames

,,_,._iIJ Research

v'4DIF Center

,Title of Investigation

Laminar Flow Fairings for Acoustic Sensors and Arrays

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Clifton Home, Kevin James, and Chris Allen, ARC

Funding

Year Initiated FY97

Total prior to FY

Total expendedin FY 97

In-house

(Estimated)

$8000

Expected completion date 1/1/99

Authorized in FY 97 $30,000

Requested forFY 98 $50,000

(If any)

Contracts (identify) s22.ooo (Calspan Corp- design, fabrication)

Grants (identify)

Status of Study

[_ Completed in FY r_ continued in FY 98

If continued in FY 98 [---] Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To determine the feasibility and effectiveness of using natural laminar flow (NLF) and hybrid laminar flow (HLF) fairings to

reduce the background noise of inflow sensors and multiple sensor arrays required for wind tunnel aeroacoustic test programs;

to investigate flow-acoustic interactions associatedwith boundary layer transition processes on sensor fairings in envirnoments

typical of wind tunnels used for aeroacoustic research; and to compare background noise levels of new concepts to isolated

microphones with quiet forebodies (baseline).

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

The experimental investigation, analysis, and reporting of data will continue. A preliminary design of a demonstration experiment

in the40- by 80-Foot Subsonic Wind Tunnel will be initiated, as well as a preliminary design of a large array fairing for wind

tunnel research.

Prepared by

Clifton Horne

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

AAL 247-2 (650) 604-4571
il_/l__.,,a'/A m e s

__-_i J Research

_lr' Center

Title of Investigation

Calculation of the Free Energy, Thermal Energy, and Entropy of Self-AssemblingNanostructures in Solutions

DIRECTOR'S DISCRETIONARY Fiscal Year

FUND REPORT 1997

Investigator(s) (show affiliation)

Richard L. Jaffe, ARC; Timur Halicioglu, Eloret Institute, ARC

I

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$40,000 (Eloret Institute)

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested forFY 98 $40,000

(If any)

[] Completed in FY

If continued in FY 98 ['--] With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

[] Continued in FY 98

r_ WithFY 98 funds?

Purpose of investigation

Self-assemblingsystems are of importance in molecularbiology and nanotechnology. In trying to determine whether a solute will

spontaneously self-assemble, one must understand the role of the solvent. The purpose of this investigation is to study the effect

exerted by the solvent on a chemical system in equilibrium or undergoing reaction. We want to provide an atomic level

understanding of the contributions from enthalpy and entropy to various solvation processesand reaction equilibria and kinetics.

FY 97 apptfcations of results, patents, reports/pub(ications, papers at meetings, any awards received, etc.

Planned future work

Study solvation effects on the stability of weakly bonded molecular complexes involving both hydrophobic and hydrophilic

interactions.

Prepared by [ Org. Code M/S Phone

Timur Halicioglu STC 230-3 (650) 604-1388

ARC 735 (Sep 97)E Previous editions are obsolete
j_l_l_,_Am es

._'_T_iJ Research

,'_V Center

Title of Investigation

Study and Design of Carbon Nanotube Electronic Devices

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Richard L. Jaffe, ARC; Jie Han, MRJ, Inc., ARC; P. M. Anantram, ARC; H. Dai, Stanford U.

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$12,000

$8000 (Eloret Inst.)

Expected completion date 10/31/99

Authorized in FY 97 $20,000

Requested for FY 98 $60,000

(If any)

[_ Completed in FY

If continued in FY 98 [--] With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

[]

[]

Continued in FY 98

With FY 98 funds?

Purpose of investigation

A carbon nanotube (CNT), a hollow cylinder formed by rolling over a graphene sheet, can be metallic or semiconducting,

depending on the tube helicity and diameter. Because of its small feature size, - 1-nm diameter, CNTs can be used as quantum wires

for single electron transistors or heterojunctions for diodes and transistors. The objective of this work is to explore, using quantum

mechanics calculations and molecular simulations, the possibilities for making CNT nanoelectronic devices.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Anantram, P. M.; and Han, J.: Transport through Uniform Carbon Nanotubes and Junctions. International

Conference on Molecular Electronics: Science and Technology, Humacao, Puerto Rico, Dec. 14-18, 1997.

http://scienceaaas-nasa.gov/-han/abstract/icmest97html.

Han, Jie: Energetics and Structures of Fullerene Crop Circles. Chem. Phys. Lett., Dec. 1997.

http: / / scienceanas.nasa, gov/-han / cone / coneJatml.

For a more comprehensive list of publications, see report in this document.

Planned future work

Study will continue on different designs for quantum wires, single-electrontransistors, heterojunction diodes and transistors, and

mechanical/electric devices, with increased emphasis on calculating electric properties for realistic conditions. Collaboration with

experimental work to build and test prototype devices will continue.

Prepared by Org. Code M/S

Jie Han IN T27A-1

ARC 735 (Sep 97)E Previous editions are obsolete

Phone

(650) 604-4799
DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Application of Unsteady CFD and Sensorless Adaptive Control for the Development of a Long-Term LVAD

Fiscal Year

1997

Investigator(s) (show affiliation)

Dochan Kwak, ARC; Cetin Kiris, MCAT Institute, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$18,000

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

$22,000 (MCAT Institute, ARC)

_l Completed in FY [] Continued in FY 87

If continued in FY 98 [--l With funds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To apply computational methods for developing a long-term or a permanent ventricular assist device (VAD) by implementing

adaptive control in conj unction with numerical simulations of time-varying pulsatile flow.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Various inflow cannula designs have been analyzed using a representative pulsatite flow condition from the heart. The VAD itself has been developed and tested based on constant average

dood flow rate. The current pulsatile flow analysis will help define the overall performance and will be a guide foran optimum implantation configuration. The computed results have been

_ostprocessed in movie format. The combined experimental and computational results will be used in an application to the Food and Drug Administration for human implantation.

A U.S. patent application was filed on Dec. 13, 1996, entitled-Rotary Blood Pump" (Serial #081766.886).

(iris, C.; Kwak, D.: and Benkowski. R.: Incompressible Navier-Stokes Calculations for the Development oft Left Ventricular Assist Device. Accepted for publication in Computers and

Fluids, 1997.

Kiris, C.: Kwak, D.: and Benkowski, R.: Computational Flow Analysis of a Left Ventricular Assist Device. Submitted to J. Artificial Organs.

Planned future work

The nextchallenge is to integrate the sensorless adaptive control and the flow simulation procedure for the development of a

long-termVAD. Through a full, unsteady simulation from inlet cannula to the exit of the VAD, requirements for an adaptive

control can be defined. In FY98, a fully unsteady solution procedure for the entire VAD installation geometry will be developed

and implemented.

Prepared by i Org. Code M/S Phone

Dochan Kwak ADC T27B- 1 (650) 604-6743

ARC 735 (Sep 97)E Previous editions are obsolete
.__ .,,_Ames

,__-_iJ Research

'q_lF Center

Title of Investigation

Demonstration of a 7 Kelvin Pulse Tube Cooler Using Rare Earth Regenerators

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Jeffrey M. Lee and Peter Kittel, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97 (Estimated)

In-house $20,000

Contracts (identify)

Grants (identify)

Status of Study

[_] Completed in FY

If continued in FY 98 E] With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

[] Continued in FY 98

With FY 98 funds?

To investigate and demonstrate a 7 K pulse tube cooler using rare earths as the regenerator material. Two coolers will be examined.

The first will be tested using erbium-3-nickel (Er3Ni) in the form of small-sized spheres (250-_m diameter) and the second will use

neodymium (Nd)-stacked plates that are 150-p.m thick and spaced 25 p.m apart. These materials possess relatively high heat

capacity at these low temperatures over existing teadregenerators. The increased heat capacity will lead to better-performing pulse

tube coolers.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

None at this time.

Planned future work

Construction of the 7 K pulse tube will be completed, and tests to measure performance will be conducted. Heat lifted, cold

temperature, pressure oscillations, work input, and efficiency will be measured; the data will be compared to present models and to

previouscooler systems; and the results will be published in an appropriate peer-reviewed journal.

Prepared by Org. Code M/S

Jeffrey Lee SET 244-10

ARC 735 (Sep 97)E Previous editions are obsolete

[Phone

E

[ (650) 604-5693
TitleofInvestigation

WirelessVideoMeasurements ofRotorBladeDisplacement adDeformation

Investigator(s) (showaffiliation)

DouglasL.Lillie,ARC;AlanJ.Wadcock, SterlingSoftware, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$30,000

Expected completion date 10/31/99

Authorized in FY 97 $30,000

Requested for FY 98 $50,000

(If any)

1-7 Completed in FY [] Continued in FY 98

If continued in FY 98 1--7 Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

iTo demonstrate a portable system for the measurement of rotor blade displacement and deformation. Portability of the system is

used to describe the self-contained nature of the proposed system, which requires ZERO slip ring channels for either signal

transmission or power supply.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

None.

Planned future work

Plans are to:

(1) Identify suitable power packs for camera and strobe.

(2) Develop strobe control hardware and image acquisition software.

(3) Design and build hardware for camera calibration.

(4) Perform static checkout of the video telemetry system.

(5) Check out rotating system.

Prepared by M/S

T12-B Alan Wadcock

Org. Code

I ARA

Phone

(650) 604-4573

ARC 735 (Sep 97)E Previous editions are obsolete
,_Ames

Research

"_t.,enter

DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Validation of a Nose-Channel Concept for Supersonic Drag Reduction

Fiscal Year

1997

Investigator(s) (show affiliation)

Mark E. Newfield, ARC; Stephen M. Ruffin, Georgia Institute of Technology

Funding

Year Initiated FY97

Total priorto FY 97

Total expended in FY

In-house

Contracts (identify)

Grants (identify)

Status of Study

97 (Estimated)

$40,000

Expected completion date 10/30/99

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

[-7 Completed in FY

If continued in FY 98 r-I With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

[] Continued in FY 98

[] With FY 98 funds?

Purpose of investigation

To conduct an experimental proof-of-concept study to validate the computationally predicted drag reduction at supersonic speeds

for a body with a hollow channel extending from the nose to the trailing edge. This objective is being accomplished by measuring

the lift and drag performance (from time of arrival and shadowgraph image trajectory analysis) of conventional and channeled

axisymmetric sphere/cone models flying in the Ames Ballistic Range.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Ruffin, S. M.; and Gupta, A.: Supersonic Channel-Airfoils for Reduced Drag. AIAA Paper 97-0517, Jan. 1997.

Planned future work

Research will focus on making high-fidelity measurements of lift and drag versus angle of attack from trajectory analysis of

Ballistic Range sphere/cone nose-channel concept models. Concurrently, sonic boom pressure signature measurements will also be

made to validate predicted reductions for nose-channel configurations. Computational and experimental investigations of more

complicated three-dimensional (3-D)bodies will also be explored.

Prepared by

Mark E. Newfield

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

STA 230-2 (650) 604-4893
__.._Ames

P_.li_._i_ Research

"_lW Center

DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

Simulation Modeling Investigations of the Terrestrial Carbon Cycle

Fiscal Year

1997

Investigator(s) (show affiliation)

Christopher Potter, ARC; Steven Klooster, California State University; Vanessa Brooks, JCWS, ARC

, Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$5000

$35,000 (JCWS Services, ARC)

Expected completion date 1/9/99

Authorized in FY 97 $40,000

Requested for FY 98 $40,000

(If any)

_-] Completed in FY [] Continued in FY 98

If continued in FY 98 [--] Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To overcome most of the significant technical obstacles to development of a computing and visualization framework that will help

in coupling and testing model algorithms of physical and biogeochemical controllers on carbon trace gas emissions from a dynamic

global land surface simulation.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

A manuscript has been submitted to the Ecological Society of America Bulletin.

Planned future work

When completed, a developed dynamic ecosystem model, which will run on a regional or global grid structure, will help enable

scientific investigations of transient biosphere interactions with atmospheric chemistry and climate on a planetary scale. It will be

among the first ecosystem models to include process-oriented controls over global hydrologic, energy, and ecosystem trace gas

exchange with a changing land surface. This general outcome is a crucial element of the Strategic Plan for NASA's Mission to

Planet Earth (MTPE).

Prepared by

Christopher Potter

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

! SGE 242-4 (650) 604-6164
_i',,a/Ames

c"eeS arch

Title of Investigation

Adaptation of Bone to Mechanical Stimulation:

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Development and Characterization of a Unique Osteoblast Loading System

Investigator(s) (show affiliation)

Nancy D. Searby, Emily Morey-Holton, and Ruth Globus, ARC; Ekhson Holmuhamedov, Mayo Clinic

Funding

Year Initiated FY96

Total priorto FY 96

Total expended in FY 97

In-house

Contracts (identify)

Grants (identify)

Statusof Study

$40,000

(Estimated)

$40,000

Expected completion date 10/30/98

Authorized in FY 97 $40,000

Requested for FY 98 0

(If any)

[-7 Completed in FY [] Continued in FY 98

If continued in FY 98 [] With funds remaining? r--] With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To determine the role of the cytoskeleton and attachments to the extracellular matrix in the response of bone-forming cells, called

osteoblasts, to mechanical loads. To accomplish this, an apparatus is under development that provides mechanical loads to

osteoblasts in culture. Experiments using this apparatus will lead to a better understanding of the role that osteoblasts play in situ

as they modify bone structure in response to altered mechanical loads, as generated by physical activities or exposure to spaceflight.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

The prototype loading system has been developed, and is presently undergoing engineeringperformance, cell biocompatibility, and

science characterization testing. Osteoblast cytoskeletal and extracellularmatrix proteins were effectively localized. Use of the

loading system was proposed in response to a NASA Research Announcement, and will be included in future proposals.

Planned future work

Engineering performance and cell biocompatibility testing will be completed, the computer control system will be enhanced, and

additional loading systems will be constructed to generate a sufficient number of samples for statistical analysis of the results

obtained from experiments. Science studies will be performed to investigate the effects of mechanical loading on cytoskeletal and

extracellular matrix proteins of osteoblasts, and initial feasibility of constructing a model based on a structural analysis of the cell's

response to loads will be assessed.

Prepared by Org. Code M/S Phone

SLR 236-7 (650) 604-6794 Nancy Searby

ARC 735 (Sep 97)E Previous editions are obsolete
I

Title of Investigation

Dexterous Walking for Mobility in Unstructured Terrain

Investigator(s) (show affiliation)

Michael Sims, David Wettergreen, Hans Thomas, ARC; John Bares, Dimitrious Apostolopolous, Carnegie Mellon Univ.

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expended in FY 97

In-house

(Estimated)

$40,000

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested forFY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

Status of Study

[-7 Completed in FY [] Continued in FY 98

If continued in FY 98 D Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To develop gait planning and control for high-degree-of-freedom walking robots with application to locomotion in unstructured,

rough terrain. This effort will develop new control techniques for dexterous walking and mobility, with an emphasis on behaviormd neural-based methods. In addition, these control techniques will allow the integration with reactive and deliberative control

methodologies. To support development of these new algorithms, both a virtual simulator and a walking mechanism hardware

testbed will be developed to demonstrate rough-terrain locomotion.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

_Ione.

Planned future work

The hardware testbed will be completed and then application of new control techniques will be carried out.

Prepared by

Hans Thomas/Michael Sims

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code M/S Phone

IC 269-3 (650) 604-5562
DIRECTOR'S DISCRETIONARY

FUND REPORT

Title of Investigation

The Origin and Control of 3-D Phenomena in Nominally 2-D Flows

Fiscal Year

1997

Investigator(s) (show affiliation)

Murray Tobak, ARC; Jonathan H. Watmuff, MCATInstitute, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$40,000

Expected completion date 10/31/98

Authorized in FY 98 $40,000

Requested forFY 98 $40,000

(If any)

[--] Completed in FY

If continued in FY 98 l_ With funds remaining?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

[] Continued in FY 98

rx] With FY 98 funds?

Purpose of investigation

To investigate the phyical processes leading to the formation of weak streamwise vortices in nominally two-dimensional (2-D)

boundary layer flows.

To explore the role of pressure gradient as a parameter for controlling the subsequent development of the vortices.

To explore the stability characteristics of the streamwise vortices.

To explore conditions under which interactions between the vortices and other disturbances [e. g., Tollmien-Schlichting (TS)

waves] are favorable (e. g., suppression of TS wave growth)or adverse (e. g., increased TS growth leading to premature transition to

turbulenceS.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Watmuff, Jonathan H.; and Tobak, M.: Flow Quality and Boundary LayerTransition. Bull. Am Phys. Soc., 1997 (to appear).

Planned future work

Testing of the effect of the wire wake-induced vortices will continue. Multiple wires will be used to explore sensitivity to spanwise

length scale. Motion of the wire will be used to explore the dynamic sensitivity.

Prepared by Org. Code M/S

M. Tobak / J. H. Watmuff ADF ! 260- I

L

ARC 735 (Sep 97)E Previous editions are obsolete

Phone

(650) 604-5855
Title of Investigation

Super Low Thermal Conductivity and Low-Density Ablative Composites

Investigator(s) (show affiliation)

Huy Tran and Christine Johnson, ARC

Funding

Year Initiated FY96

Total prior to FY 97 0

Total expended in FY 97

In-house

(Estimated)

$20,000

Expected completion date 9/30/98

Authorized in FY 97 $40,000

Requested forFY 98 $40,000

(If any)

Contracts (identify)

Grants (identify)

$20,000 [LLNL (see IASA*)]

Status of Study

[--] Completed in FY [] Continued in FY 98

If continued in FY 98 r_ Withfunds remaining? [] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To demonstrate the feasibility of chemically combining aerogel technology with the latest lightweight ceramic ablator material to

produce an ultralow thermal conductive in-depth material with high ablative performance at the outer surface. This objective is

being accomplished by integrating the aerogel material for its super insulative properties and different light ceramic ablators

material for their ablative characteristics.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

After the purchase request is processed by our procurement office, LLNL will start making the aerogel in conjunction with

lightweight ceramic ablators (LCAs). Also, arcjet testing is planned to evaluate the material ablation characteristic as well as the

thermal response. Virgin LCA samples will be tested as a baseline for comparison. Crush properties of the system are also being

investigated.

*Interagency Space Act

Prepared by Org. Code M/S i Phone

Huy Tran STM 234-1 (650) 604-0219

ARC 735 (Sep 97)E Previous editions are obsolete
__+_l_'Ames

.I_-r_iJ Research

,_DY Center

Title of Investigation

A Deployable Vortex Diffuser for Reducing Blade-Vortex Interaction Noise

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

Chee Tung and Ken McAlister, ARC

Funding

Year Initiated FY97

Total priorto FY 97 0

Total expendedin FY 97

In-house

Contracts (identify)

Grants (identify)

Status of Study

(Estimated)

$40,000

Expected completion date 5/1/99

Authorized in FY 97 $40,000

Requested for FY

(If any)

[-7 Completed in FY IX-] Continued in FY 98

If continued in FY 98 [] With funds remaining? [-7 With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To change the structure of the trailing vortex of helicopter rotor blades by reducing the magnitude of its peak velocity. The civilian

helicopter fleet cannot reach full potential because of the noise level during descent into heliports near communities. Muchof the

noise comes from rotor blades cutting through their own wake--a phenomenon referred to as blade-vortex interaction (BVI) noise.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

The computational fluid dynamics (CFD) solutions of a candidate trailing-edge spoiler have been completed. Use of the spoiler

produced the peak velocity of the trailing vortex. Results from this study were presented at the Director's Discretionary Fund poster

session on November 4, 1997.

Planned future work

A hover test will be performed to quantify the performance of a static vortex spoiler design. The results are expected to indicate the

presence of strong turbulent mixing and a decrease in the strengthof the vortex. A mechanism for deploying the spoiler on the blade

will be designed.

Prepared by Org. Code M/S Phone

Chee Tung ARA T- 12B (650) 604-5241

i

ARC 735 (Sep 97)E Previous editions are obsolete
il_..,,_Ames

,,_,_ (Research

Title of Investigation

;Adaptation to Virtual Gravitational Environments

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

_,.B. Welch, ARC; M. Aratow, ARC Assoc.; R. Whalen, ARC; W. L. Boda, Sonoma State U.; A. Hargens, UC, San Diego, ARC

Funding

Year Initiated FY96 Expected completion date 10/31/98

Total priorto FY 97 0 Authorized in FY 97 $70,000

Total expended in FY 97

In-house

(Estimated) Requested for FY 98 $30,000

(If any)

$70,000

Contracts (identify)

Grants (identify)

Status of Study

[] Completed in FY [] Continued in FY 98

If continued in FY 98 rM--]With funds remaining? I--] With FY 98 funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To (1) simulate many of the bodily and visual effects of ambulating on Mars by means of a combination of lower body positive

pressure and a computer-generated virtual environment with which the subject interacts by means of a motor-driven treadmill on

which he/she walks; and (2) demonstrate that human beings are able to adapt their walking behavior to this simulation while

simultaneously maintaining their ability to walk in the normal (l-g)environment.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Planned future work

To (1) determine the optimal training procedures for producing adaptation and dual adaptation to the Mars Gravity Simulator; and

(2) examine various parameters of this adaptation, such as its longevity, the best discriminative cues for dual adaptation, and the

generalizability of adaptation and dual adaptation to other environments.

Prepared by Org. Code I M/S [Phone

Robert B. Welch I SLR 239- I l (650) 604-5749

I

ARC 735 (Sep 97)E Previous editions are obsolete
__.._Ames

,__J Research

_Center

Title of Investigation

Fastenerless Structural Connections for Tiltrotor Aircraft

DIRECTOR'S DISCRETIONARY

FUND REPORT

Fiscal Year

1997

Investigator(s) (show affiliation)

John Zuk, ARC; Clem Hiel, W. B. Goldsworthy & Assoc., Inc.

Funding

Year Initiated FY96

Total priorto FY 97 $40,000

Total expended in FY 97

In-house

Contracts (identify)

G rants (identify)

Status of Study

(Estimated)

$40,000 (Sci. Appl. Int'l. Corp.)

Expected completion date 10/31/98

Authorized in FY 97 $40,000

Requested for FY

(If any)

[-"1 Completed in FY r_ Continued in FY 98

If continued in FY 98 [] With funds remaining? t_] With FY funds?

If transitioned to other funding, to RTOP (number?)

to Program (name?)

to Other (identify)

Purpose of investigation

To conduct innovative research leading to the development of a new class of fastenerless connections, called "snap joints," for

assembly of composite structures, with special emphasis on tiltrotor aircraft.

FY 97 applications of results, patents, reports/publications, papers at meetings, any awards received, etc.

Fabricated and tested a new snap joint fiber architecture and compared results with a current state-of-the-art laminated fiber

architecture. The new snap joint architecture increased the interlaminor shear strength by at least a factor of five. Results were

reportedin an article in SAMPE J., vol. 35, no. 1, Jan./Feb. 1998.

Planned future work

(1) Redesign a generic composite component on a tiltrotor aircraft using snap joint fastening. Conduct design, development, and

payoff studies.

(2) Seek funding for continuing activity from a new funding source.

Prepared by

John Zuk

ARC 735 (Sep 97)E Previous editions are obsolete

Org. Code

APT

M/S

237-2

Phone

(650) 604-6568

Form Approved

REPORT DOCUMENTATION PAGE ousNo,ozo4.olse

Public reportingburden for thiscollection of informationis estimated to average 1 hourper response,includingthe timefor reviewinginstructions,searchingexisting data sources,

gatheringand maintaining the data needed, and completingand reviewingthe collectionof intormation. Sendcomments regardingthis burden estimate or any other aspect of this

collectionof information,includingsuggestionsfor reducing thisburden, to WashingtonHeadquarters Services, Directoratefor intormalion Operations and Reports, 1215 Jefferson

Davis Highway,Suite 1204, Arlington,VA 22202-4302, and to the Office of Management and Budget,Paperwork ReductionProject(0704-0188). Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

March 1998

4. TITLE AND SUBTITLE

Director's Discretionary Fund Report for Fiscal Year 1997

6. AUTHOR(S)

Ames-Moffett Investigators

7. PERFORMINGORGANIZATION NAME(S)AND ADDRESS(ES)

Ames Research Center

Moffett Field, CA 94035-1000

9. SPONSORING/MONITORINGAGENCYNAME(S)AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

3. REPORT TYPE AND DATES COVERED

Technical Memorandum

5. FUNDING NUMBERS

274-53-71-39

8. PERFORMING ORGANIZATION

REPORT NUMBER

A-98-08589

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/TM--1998-112216

11. SUPPLEMENTARY NOTES

Point of Contact: John T. Howe, Ames Research Center, MS 200-16, Moffett Field, CA 94035-1000

(650) 604-5500

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified -- Unlimited

Subject Category 99

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

This technical memorandum contains brief technical papers describing research and technology development programs sponsored by the Ames Research Center Director's Discretionary Fund during fiscal year

1997 (October 1996 through September 1997). Appendices provide administrative information for each of

the sponsored research programs.

14. SUBJECT TERMS

Director's Discretionary Fund, Space science, Life science, Aeronautics,

Space and terrestrial applications

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION

OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18

298-102

15. NUMBER OF PAGES

88

16. PRICE CODE

A05

20. LIMITATION OF ABSTRACT