NASA Engineering & Safety Center

2014 TECHNICAL UPDATE

THE NESC

National Aeronautics and Space Administration
Systems

Engineering 

Office 

NESC

Principal 

Engineers

Management

and Technical

Support Office

NESC Chief 

Engineers

NESC Review Board

Technical

Discipline Teams

PEs SEO

NCEs MTSO

Office of the 

Director

NASA

Technical 

Fellows

NRB

NASA Office of Chief Engineer

NASA Engineering and Safety Center

The NASA Engineering and Safety Center (NESC) 

leadership team is pleased to introduce the 2014 

NESC Technical Update. This publication is an 

example of one of the knowledge products we use to share 

discoveries, lessons learned, and technical solutions with 

the Agency and the broader engineering and technical 

community. This year, the NESC experienced a change in 

leadership with the departure of two of the driving forces 

behind the NESC since its inception in 2003. Ralph 

Roe, the NESC’s first Director, was named the NASA 

Chief Engineer, and Dawn Schaible, the former manager 

of the NESC Systems Engineering Office, was named 

NASA Deputy Chief Engineer. They may have moved 

on, but their vision for the NESC endures as a worldclass technical resource to address NASA’s toughest 

problems and provide timely, value-added solutions to 

those problems. All members of the NESC management 

team, past and present, share that common vision. Tim 

Wilson now serves as the NESC Director, having served 

as the Deputy Director since 2006 and as an NESC Chief 

Engineer since NESC formation. Mike Kirsch now serves 

as the NESC Deputy Director, having briefly served as the 

Management and Technical Support Office Manager in 

2013 and as an NESC Principal Engineer since 2004. 

Conveying knowledge

Previous editions of the NESC Technical Update 

showcased a wide variety of NESC activities from the 

preceding year using short descriptions and illustrations. 

However, an objective of this year’s publication is to show 

the reader how NESC assessments may be part of a 

broader picture than the scope of the original assessment, 

or connect some of the themes drawn from separate 

assessments. Consider the study the NESC performed 

on a 1967 X-15 flight accident. The objective of the study 

was to find lessons learned from that incident that could 

be applied to current NASA projects. A contributing 

factor to the accident was the X-15’s adaptive flight 

control system, which has similarities to what NASA’s 

Space Launch System will be employing and the focus 

of a separate NESC assessment. In addition, other NESC 

Moving into a New Era

Timmy R. Wilson

Director

Michael T. Kirsch

Deputy Director

1

NESC overview

The NESC Organizational Structure
Aeronautics Research

2%

Science

18%

Broad Agency/External

13%

Human Exploration

and Operations

66%

Space

Technology

1%

Accepted Requests by Mission Directorate

Sources of Accepted Requests

Accepted Requests by Year

Safety & Mission

Assurance at Centers 3%

Program

Management 

18%

NESC 19%

Engineering & Scientific 

Organizations 45%

Anonymous 

1% 

Other NASA

Offices 3%

Office of Chief 

Engineer 2 %

Center 

Management 

2%

Office of Safety and

Mission Assurance 3%

External to Agency 4%

48 45

67 59

48 53 53 48 54 58 60

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Accepted Requests: 593 total

teams have been evaluating 

the use of commercial-offthe-shelf (COTS) electronics 

components on spacecraft. The 

X-15 accident was attributed in 

part to the use of certain COTS 

equipment. 

Another objective of the NESC 

Technical Update is to serve as an introduction to the NESC 

through our accomplishments. From an organizational 

standpoint, the NESC falls under NASA’s Office of the 

Chief Engineer. This arrangement separates the NESC 

from the NASA mission directorates, programs, projects, 

and Centers, and allows independence, objectivity, and 

flexibility when working with other NASA organizations. 

The proven NESC structure

The NESC is structured to quickly and efficiently apply 

the concept of tiger teams (called assessment teams in 

the NESC) to address technical problems as they arise. 

NESC core team members are full-time employees of the 

NESC and form the nucleus of each assessment team. 

The NESC Principal Engineers, NESC Chief Engineers, 

NASA Technical Fellows, Systems Engineering Office, 

and the Management and Technical Support Office 

make up the core team, led by the NESC Director and 

his office. Members of Technical Discipline Teams (TDTs) 

form the NESC extended team. The TDTs are populated 

with engineers and scientists 

chosen for their technical 

knowledge and experience, 

and drawn from within NASA, 

academia, industry, or other 

government agencies. There 

are 18 TDTs, each focused 

on an engineering discipline, 

and led by a NASA Technical Fellow or TDT Lead. When 

the assessment lead determines the requirements for an 

assessment, he or she draws the appropriate personnel 

from the TDTs through the NASA Technical Fellows.

The NESC Review Board (NRB) is a unique element of the 

NESC, which is comprised of members from each of the

NESC offices, and represents all 10 NASA Centers and 

each technical discipline. The NRB approves all technical 

products generated by the NESC and its assessment 

teams. The NESC is successful because a diversified 

technical experience base creates different vantage 

points from which to approach each issue — resulting in 

a robust decision-making process.

The NESC provides the framework and infrastructure to 

find and focus engineering talent. Any success the NESC 

has achieved is a testament to the extended NASA team 

and the limitless knowledge and experience its members 

provide as they tackle the Agency’s most difficult

technical challenges. □

The NESC Review Board (NRB) is a unique 

element of the NESC, which is comprised 

of members from each of the NESC offices, 

and represents all 10 NASA Centers and 

each technical discipline.

2

All statistics as of December 31, 2014

3

The NESC Assessment Team Structure

Approximately 700 Members

NESC Extended Team

18 Technical

Discipline Teams

• Aerosciences • Avionics

 • Electrical Power 

• Flight Mechanics

• Guidance, Navigation,

and Control • Human Factors

• Human Spaceflight Operations

 • Life Support/Active Thermal

• Loads and Dynamics

• Materials

• Mechanical Systems

• Nondestructive Evaluation

• Passive Thermal • Propulsion

• Robotic Spaceflight • Software

• Structures

• Systems Engineering

Member

Percentage

NESC Core Team 

Approximately 60 Members

NESC Principal Engineers

Assessment Team Leads

NESC Chief Engineers

NESC Points of Contact

at each Center

Management and Technical 

Support Office

Contracts, Budgets,

Partnerships

NASA Technical Fellows

Senior Technical Experts/TDT

Leadership

Systems Engineering Office

Technical Integration

and Assessment Support

Assessment

Team

NASA

71%

Industry

22%

Academia

5%

Other

Government

Agencies

2%

NESC overview
1. Fundamentals of Turbofan 

Aircraft Engine Control

This presentation covers the basic 

principles behind modeling the engine 

system for control design and how 

the safety and operational limits are 

implemented in the engine control to 

provide safe and reliable operation.

2. Rationale for Selected MIL-STD1540E Thermal Test Requirements

Testing to MIL-STD-1540E requirements 

over past decades has demonstrated 

its value in support of military programs 

for identifying design workmanship 

issues early, providing realistic flight 

environments, and demonstrating flight 

worthiness.

3. An Overview of Fastener 

Requirements in the new NASASTD-5020

This presentation provides an overview 

of the contents of the new standard, 

including rationale for differences 

from NSTS 08307, and case studies 

to illustrate application of some of the 

concepts.

4. Fundamentals of Spacecraft

Attitude Control

Spacecraft attitude control systems are 

onboard systems that autonomously 

orient a spacecraft relative to a target 

reference frame. An understanding of 

the disturbance environments in various 

flight regimes is critical to design 

choices.

5. Fundamentals of Launch Vehicle 

Flight Control System Design

This presentation is intended to be an 

introductory overview of launch vehicle 

guidance, navigation, and control (GNC) 

for ascent. The video will look at the big 

picture of how these three disciplines 

are interconnected in a launch vehicle 

design.

6. Fundamentals of Aircraft

Flight Control

This short course covers the major 

control design issues and what to 

beware of in the design process and 

shows ways to design a robust control 

design method with some of the real 

world issues involved.

7. Fundamentals of Kalman

Filtering and Estimation

Kalman Filtering and Least Squares 

Estimation have been at the heart of 

the GNC system design within the U.S. 

Space Program since its inception. 

Beginning with linear systems, the basic 

concepts will be introduced, and several 

examples will be presented.

8. NASA Space Situational

Awareness (SSA) Overview

This talk describes the Agency’s role in 

SSA, with particular emphasis on the 

robotic conjunction assessment effort. 

SSA policy, procedures, interfaces, and 

goals will be discussed.

9. Metal Fatigue Part 1

This presentation provides a cursory 

overview of metal fatigue, which includes 

the basic elements of stress-life (S-N) 

fatigue, strain-life, and linear elastic 

fracture mechanics. Details regarding

the micro- and macro-mechanics associated with metal fatigue crack nucleation, 

initiation, and propagation are also 

addressed.

10. The Evolution of Guidance, 

Navigation, and Control (GNC) in Mars

Entry, Descent, and Landing (EDL)

This presentation describes the 

history of EDL GNC as represented 

by its functional and performance 

requirements, and the architectures and 

implementations needed to satisfy them. 

This video starts with the unguided 

Viking legged-landers, continues with 

the Mars Exploration Rover airbaglanders, and concludes with Curiosity’s 

fully guided entry and SkyCrane-lander.

The NESC takes a broad approach when it comes to sharing the knowledge it has accumulated from the 

hundreds of technical assessments conducted since 

its inception more than a decade ago. To capture and 

disseminate that knowledge to all who may need it — 

within NASA, industry, and academia — the NESC offers 

a wide variety of knowledge services and products that 

can be readily accessed and consumed. From technical 

assessments and reports to databases and videos, 

these products bring the data gathered in the field to the 

people it will benefit most, and capture that knowledge 

for generations to come.

Engineering reports

The detailed engineering and analyses generated 

from each assessment are captured in comprehensive 

engineering reports and converted into NASA Technical 

Memorandums (TM) for permanent archive and access. 

Capturing engineering analyses in formal reports instead 

of briefing slides has been on-going since the Columbia 

accident investigation. In 2014, more than 30 TMs were 

generated by NESC teams whose members span all 10 

NASA Centers. TM topics touched on a broad range of 

NASA programs across all NASA mission directorates. 

All publicly available NESC reports are located at

ntrs.nasa.gov.

Technical bulletins

Occasionally, significant and noteworthy data found 

during NESC assessments are turned into one-page

technical bulletins. The bulletins condense new 

knowledge or best practices into quick and easy

reads, while also linking to additional reference material. 

NESC Technical Bulletins are located at nesc.nasa.gov.

Technical update

At the end of each year, the NESC Technical Update 

serves as a summary of significant contributions to 

the Agency, and also serves as a way to communicate

NESC knowledge products. The NESC Technical Update 

can be found at nesc.nasa.gov.

NESC knowledge products and summaries of our latest 

efforts can be found at nesc.nasa.gov.

Lessons learned

An Agency-level lessons learned database called the 

Lessons Learned Information System (LLIS) is used to 

capture important and broadly applicable lessons learned. 

In some cases, the lesson may be significant enough that 

it is used to update a NASA standard. NESC and Agency 

lessons learned can be found at llis.nasa.gov. 

Video academy

The NESC Academy is a website featuring nearly 300 

informative lessons on topics relevant to current NASA 

issues and challenges. They offer the audience a virtual 

classroom experience on a myriad of technical topics, 

which this year ranged from fundamentals of aircraft 

engine control and metal fatigue to Kalman filtering and 

space situational awareness. NESC Academy videos 

have received more than 17,000 views since inception in 

2012. In 2014, the Academy also featured 44 technical 

webcasts as a service to the discipline communities. 

Viewers could send in questions to the presenter during 

the live broadcast. The NESC is also processing major 

new content that includes over 60 videos from the JSC 

U.S. Spacesuit Knowledge Capture Series to make 

available on the NESC Academy. 2015 will bring even 

more capabilities to the website, including mobile access 

and personalized training. NESC Academy videos are 

found at nescacademy.nasa.gov.

Additional knowledge service products

Other knowledge sources to which the NESC contributes 

include the NASA Engineering Network, an online space 

for communities of practice, as well as workshops, 

forums, and technical interchange programs. The NASA 

Technical Fellow’s communities of practice can be found 

at nen.nasa.gov. 

4

ntrs.nasa.gov

nesc.nasa.gov

nescacademy.nasa.gov

nen.nasa.gov

llis.nasa.gov

5

Top 10 Most Viewed NESC Academy Videos

knowledge products knowledge products

Preserving Knowledge for the Future 
had put the experiment on another aircraft and didn’t 

see any problems and assumed, without doing rigorous 

analysis of hardware design, that it would be okay in all 

flight environments.” 

.

For the X-15, the electronic hardware, combined with 

the pressure and temperature of the atmosphere at 

high altitude, led to the plane’s catastrophic electrical 

issues. Orr noted that ballistic space planes and crewed 

commercial concepts currently being developed are likely 

to spend more time in the same critical region as X-15 and 

experience the same types of environments. 

Classical techniques can

predict complex behavior

“There is a lot of insight to be gleaned from simple 

mathematical, rigorous analysis,” said Orr. To characterize 

the X-15’s flight control system, analysis techniques that 

were available during X-15’s operation were combined 

with new computer simulation tools to allow for quicker 

and more efficient evaluation of data. 

Orr noted that today’s analysis methodology relies heavily 

on simulation, which has led to classical approaches 

falling out of favor. “Using approximation, or first order 

principles, to understand system behavior is absolutely 

paramount,” said Orr. “Then it can be coupled with 

simulation to understand the underlying physics.” Orr also 

noted that describing function (DF) analysis was used to 

understand the X-15 flight control system’s limit cycle 

oscillation behavior, which prevented the aircraft’s pitch 

recovery. “If today’s designers relied only on simulation, 

they may not have found this case,” said Orr. “DF 

analysis is thought of as a lost art, though it’s an insightful 

technique.” 

Communication is key to situational awareness

During the X-15 flight, ground control staff did not 

communicate subsystem anomalies to the pilot, assuming 

the pilot had better situational awareness. In addition, not 

all flight data being telemetered was immediately available 

to ground control or required human analysis before 

recommendations could be made. This combination led 

to an overall lack of communication between the pilot and 

ground control, which contributed to confusion for the 

pilot, who also was receiving conflicting information from 

failing avionics systems. Orr noted that any anomaly of 

significance to aircraft safety should be relayed by ground 

control to the pilot or crew, even if it is redundant. This 

combination of events prevented the team from placing 

priority on restoring the X-15 to a safe state over the 

continuation of science objectives.

Design for the average human

“We need to design an interface for average humans, even 

if it is operated by astronauts,” said Orr. On the X-15, for 

example, the instrument panel had changed over time as 

“If today’s designers relied only 

on simulation, they may not have 

found this case”

—Dr. Jeb Orr

Continued on next page

An adaptive flight control system currently baselined for use on NASA’s Space Launch System (SLS) 

borrows concepts from the design of the X-15, an 

experimental aircraft once operated by NASA and the 

U.S. Air Force. The manned hypersonic vehicle, which 

flew at speeds of up to Mach 6.7 and altitudes up to 

350,000 feet, demonstrated new technologies including a 

“self-adaptive” control system. Though highly advanced 

for its time and successfully proven on previous flights, 

this control system contributed to a fatal X-15 accident in 

1967. The initiating event for this accident was in essence 

an electrical anomaly, originating in an experiment 

payload, which coupled into the guidance, navigation, 

and control avionics creating a disastrous situation. 

And as is typically the case with accidents, additional 

compounding circumstances created a situation from 

which the pilot could not recover. 

Learning from a 1967 accident

To more fully understand the role that the adaptive control 

system played in the accident, the NESC sponsored a 

comprehensive analysis of the X-15 mishap in parallel 

with the SLS adaptive control risk-reduction flight test 

effort that was conducted in 2013. The primary goal of the 

X-15 analysis was to evaluate the applicability of lessons 

learned not only to SLS but to other emerging aerospace 

systems. “New sub-orbital commercial concepts are 

proposing flight profiles similar to X-15 with fast reentries 

and high dynamic pressures, and will encounter similar 

flight control, system integration, and environmental 

challenges,” said Dr. Jeb Orr of Draper Laboratory and a 

member of the NESC Guidance, Navigation, and Control 

Technical Discipline Team. “We need to understand to 

what extent lessons learned from the X-15 Program could 

be applied as risk mitigation to these emerging concepts.” 

The X-15 analysis taught us about engineering, human 

factors, and design shortfalls that unfortunately resulted 

in a major accident. The SLS adaptive control algorithm 

design approach mitigated these shortfalls, and the 2013 

flight test campaign advanced the technical maturity and 

flight readiness of the algorithm.

Test COTS equipment for use

in its intended environment

Just before the 1967 accident, designers added a traverse 

probe experiment to the X-15 starboard wing pod to 

measure shock geometry. The experiment had flown 

previously on X-15 at lower altitudes without incident 

and was deemed acceptable for all flight environments. 

Unknown to designers, the probe’s commercial-off-theshelf (COTS) motor contained a high voltage component, 

which at higher altitudes caused arcing and introduced 

electrical disturbances into safety-critical aircraft 

systems. This started a chain reaction that led to the 

eventual breakup of the aircraft.

“A complacent culture develops that marginalizes risk,” 

said Orr. As the X-15 had been flying for several years, it 

was viewed more as an operational versus experimental 

platform. Numerous X-15 modifications were added 

without a clear understanding of potential subsystem 

interactions with avionics hardware. Without the original 

design specifications for the motor, designers did not 

know the motor would generate high voltages. “They 

50 Years Later, the X-15 Is Still

a Platform for Knowledge

6 7

featured knowledge
switches and indicators were added or moved, eventually 

leaving all three X-15 aircraft with different instrument 

panels. In addition, each aircraft had slightly different 

emergency procedures depending on what equipment 

was installed. “That was fine in 99% of flights, but when 

things went wrong, it led to confusion. Astronauts are 

highly trained, but in times of high stress, they need a 

simple interface that gives them an unimpeded ability 

to maintain the safety of the spacecraft and its crew.” 

In the case of the X-15 accident, a primary contributing 

factor was a lack of mode indication on a critical flight 

instrument, which had been uniquely modified to support 

a specific science objective.

The X-15 accident followed a familiar pattern where 

several unrelated, but concurrent failures came together 

to create an unrecoverable event. Several subsystem 

anomalies occurred, which were considered benign in their 

individual subsystems, such as the limit cycle oscillation 

in the X-15’s flight control system. “But because it was 

coupled with other failures, it did cause an accident,” said 

Orr. “If things don’t behave as expected, you have to be 

willing to stand down and understand the risk and threat 

before continuing flight operations.” □

Reference NASA/TM-2014-218538

Describing function

Describing function (DF) analysis is a classical 

technique to predict the behavior of certain types 

of nonlinear control systems. The technique was 

developed in the early twentieth century partly to 

provide an analytical method to supplement the 

limited computer capabilities of the time. Now, 

combining classical theory with modern numerical 

simulations, DF analysis has re-emerged as a 

mathematically rigorous and powerful tool for helping 

control engineers understand why and under what 

conditions nonlinear control systems oscillate in 

undesirable ways.

Protecting against failures from

nonessential equipment

NASA spacecraft and commercial aircraft designers 

now go to great lengths to protect flight-critical 

systems from potential hazards generated by 

“nonessential” systems such as experiments 

flying on the International Space Station or inflight entertainment systems in commercial aircraft. 

Engineers also went to great lengths to protect flightcritical avionics in the Space Shuttles from problems 

with experiments that operated in the orbiter’s 

payload bay.

X-15, 50 Years Later

Continued 

Test trajectories flown repeatedly by NASA’s F/A-18 while testing the SLS AAC.

Simplified block diagram of the SLS flight control system.

OCA

Highpass filter

Vehicle

dynamics

Model Adaptive law Lowpass filter

PID

DCA

Bending filters

Testing the SLS Adaptive Augmenting Control

I

n 2013, a partnership of NASA organizations including 

MSFC, AFRC, NESC, and the Science and Technology 

Mission Directorate Game Changing Technology Office, 

conducted a series of F/A-18 research flights to test Space 

Launch System (SLS) prototype software, including the 

previously untested adaptive augmenting control (AAC) 

component. 

Because SLS will deliver more payload to orbit and produce 

more thrust than any other vehicle, past or present, it opens 

the way to new frontiers of space exploration as it carries 

the Orion Multi-Purpose Crew Vehicle, equipment, and 

experiments into new territories. The addition of AAC to 

SLS offers significant benefits to the total attitude control 

architecture by providing the fixed gain control architecture 

with additional robustness. AAC increases flight control 

system (FCS) performance when excessive tracking error 

is present and decreases responsiveness to undesirable 

frequency content. It expands the envelope under which 

the FCS is capable of safely flying the vehicle, maximizing 

vehicle survivability and crew safety.

If there were no vehicle or environmental uncertainty, a 

fixed-gain controller could be optimized prior to flight 

with no need for adaptation; however, a review of 

historical reusable launch vehicle data from 1990 to 2002 

revealed that over 40% of failures resulting from other 

malfunctions might have been mitigated by advanced 

guidance, navigation, and control technologies. Thus, 

an algorithmically simple, predictable AAC design with 

direct ties to classical stability margins was implemented 

for SLS. It was initially formulated and tested during the 

former Constellation Program, then refined as part of 

the baseline autopilot design and flight software prototype 

for SLS. 

During flight testing on the F/A-18 Full-Scale Advanced 

Systems Testbed aircraft at AFRC, the aircraft completed 

a series of trajectories during multiple sorties with the SLS 

FCS enabled. The aircraft’s pitch rate was matched to the 

SLS and matching attitude errors for various nominal and 

extreme SLS scenarios were incorporated through the use 

of a nonlinear dynamic inversion controller. The emphasis 

of the 100-plus SLS-like trajectories was on fully verifying 

and developing confidence in the AAC algorithm in 

preparation for the first uncrewed launch of SLS. □

Reference NASA/TM-2014-218528

8

The X-15 was a high-altitude hypersonic research vehicle, operated by NASA from 1959 to 1968, used to support development of new 

technologies including propulsion, instrumentation, structures, thermal protection systems, and flight controls.

9

featured knowledge
Data

Discrete, objective, but unorganized facts about an event

Wisdom

Broad

Knowledge

Information

Organized and analyzed data that can

be used for a purpose

Knowledge

Collected information,

experience, expertise, and insight

NASA wisdom says: use these parts very 

carefully, test extensively, and gather as 

much knowledge as possible.

Extensively documented experience 

(good and bad) collected and shared 

about parts that have evolved steadily.

NASA wisdom is based on broad and 

deep knowledge of these parts that 

has enabled reliable use for decades.

Access to detailed information generally limited to important customers. 

NASA has limited experience with 

large-scale use of these parts.

Market-focused reports 

available. NASA must

generate own information.

Manufacturers supply

extensive data aimed at 

their target market.

Data generated over more than 

40 years analyzed and reported 

to provide extensive information.

NASA has ready access to 

mandated data, common

to all suppliers.

Military/Aerospace/High Reliability COTS/Automotive/COTS Plus latent defects and infant mortals and/or parts not 

suitable for the application) into flight hardware, with 

the questionable assumption that board-, box-, and 

system-level testing can effectively identify parts that 

might fail during the anticipated mission lifetime. Proper 

parts-level qualification is essential to: 1) ensure the 

part technology, design, and construction is capable 

of predictable and required performance in the space 

environment and 2) identify parts that function properly in 

terrestrial applications but may not perform safely in the 

more extreme space radiation, vacuum, vibration, and 

thermal environments found in spaceflight applications. 

Card-level, box-level, and system-level testing cannot 

replicate accelerated failure factors that voltage, current, 

and temperature stresses can provide during parts-level 

screening prior to installation on a circuit board.

Commercial parts use at NASA

NASA has successfully used commercial parts in 

spacecraft for specific and sometimes mission-critical 

applications throughout the Agency’s history. This 

has been achieved by careful selection, qualification, 

and screening. The level of screening required for 

commercial parts to ensure they will work successfully is 

highly dependent on the mission, intended application, 

environment, mission duration, and part technology. The 

level of screening is quite well characterized in existing 

NASA parts documents such as EEE-INST-002. NASA 

flies non-MIL (non-military) grade parts when the required 

functionality and/or performance is not available in MIL 

parts. If a MIL part can be used, they are preferred.

Initial qualitative analysis indicates significant differences 

in reliability and safety can result between screened MIL 

parts and unscreened commercial parts. Parts quality, 

architecture (including the selection of like or diverse 

backup systems), and mission duration are inseparable 

variables that must be traded in a mission design. One 

system architecture could use lower grade parts for 

short-duration missions (a few minutes to a few days) 

and possibly exhibit acceptable analytical system 

reliability. That same architecture may not provide the 

analytical reliability required for long-duration missions 

(a few weeks to many months) when using lower grade 

parts. Parts quality dominates system reliability in longduration missions where environmental effects like 

space radiation and single event upsets are more likely to 

occur. A system design for long-duration missions is an 

example where NASA would typically employ in critical 

applications high reliability space-qualified military grade 

parts or use highly screened and qualified COTS parts.

Alternative approaches

Any alternative approach for the use of COTS EEE 

parts in critical applications other than those that have 

proven successful, such as described in EEEINST-002 

or similar NASA documents, requires a firm basis for 

substantiation. Any approach based on architecturally 

similar redundancy and card-level, box-level, and systemlevel testing alone is not sufficient to enable widespread 

use of unscreened parts acquired from commercial 

catalog distributors in critical applications. To reduce the 

likelihood that parts failures result in unacceptable mission 

risk, standard practice dictates designers to: 1) develop 

and implement a systems engineering-oriented mission 

assurance program to address EEE parts derating, 

qualification, traceability, and counterfeit control, and 

demonstrate how it mitigates the risks associated with 

EEE parts applications, and 2) provide data supporting 

the effectiveness of the proposed screening approach, 

ensuring part failure rates are adequately bounded. □

Reference NASA/TM-2014-218261

Important definitions

COTS: An assembly or part designed for commercial 

applications for which the item manufacturer 

or vendor solely establishes and controls the 

specifications for performance, configuration, and 

reliability (including design, materials, processes, and 

testing) without additional requirements imposed by 

users and external organizations. For example, this 

would include any type of assembly or part from a 

catalog without any additional parts-level testing after 

delivery of the part from the manufacturer.

COTS Plus: A COTS part supported by test data 

available to end users establishing random failure 

rate assumptions, performance consistent with the 

manufacturers data sheet and methods to exclude 

infant mortal parts, parts with latent defects, weak 

parts, or counterfeit parts. For example, automotive 

electronics council-certified or compliant automotive 

parts are one type of COTS Plus.

Parts Qualification: Sample-based mechanical, 

electrical, and environmental tests at the piece 

parts level intended to verify that materials, design, 

performance, and long-term reliability of parts on 

the same production line are consistent with the 

specification and intended application until a major 

process change.

Parts Screening: A series of tests and inspections 

at the piece parts level intended to remove 

nonconforming and/or infant mortal parts (parts

with defects that are likely to result in early and/or 

cluster failures) and thus increase confidence in the 

reliability of the parts selected for use. 

NASA’s Commercial Crew Program (CCP) is stimulating efforts within the private sector to develop and 

demonstrate safe, reliable, and cost-effective space 

transportation capabilities to the International Space 

Station. One initiative involved investigating the possible 

use of commercial grade electronic parts in launch 

vehicle and spacecraft designs. The CCP was interested 

in data that would help frame the technical, cost, and 

schedule risk trades associated with the use of electrical, 

electronic, and electromechanical (EEE) parts of a lower 

grade than traditionally used in most NASA safety-critical 

applications. 

The fundamental question

The fundamental question is “Can commercial-off-theshelf EEE parts with limited screening be used in crewed 

flight hardware systems?” The terms “commercial-offthe-shelf parts,” or “COTS,” and “screening” are broadly 

defined and not applied consistently. Automotive, 

commercial aviation, medical, and safety conscious 

consumer electronics industries engage in assurance 

processes within their supply chain to establish a 

basis for the quality and reliability of the EEE parts 

used in their products before assembling them into 

critical applications. These assurance processes, with 

inspections and tests possibly performed on a sample 

basis depending on criticality, are intended to identify 

defects and abnormalities that serve as warning signs of 

a potential for premature failure, reduced performance, 

and safety.

Parts screening approaches 

There is a wide spectrum of approaches to parts 

screening. At one end of the spectrum, EEE parts used 

in critical space systems in general are subjected to 

100% parts-level inspections and testing to provide 

high assurance of quality and reliability. At the other 

end of the spectrum are commercial catalog parts 

that have not been subjected to any testing other than 

those established by the manufacturer. An NESC team 

analyzed two COTS parts screening approaches: one 

that employs only card-level testing coupled with boxlevel and system-level testing versus the traditional 

approach of screening at the parts level prior to card, 

box and system-level testing. The team concluded that 

there are fundamental concerns with replacing partslevel screening and qualification with card and box-level 

or system-level testing only. 

Assembling COTS EEE parts on circuit boards for space 

applications without proper parts-level qualification or 

additional screening could result in assembling good 

parts along with any weak parts (parts containing 

10 11

featured knowledge

COTS Components in Spacecraft

Systems: Understanding the Risk
and more. NDE history and inspection methods were 

reviewed, as well as risk mitigation methods used by each 

NASA Center. Locations within government and private 

industry were also surveyed. The goal was to prioritize 

risks and determine what could be done to “buy down the 

most risk,” said Prosser. 

The assessment also involved testing and analysis. 

Material evaluations of tensile strength and fracture 

toughness of materials and investigations of the 

microstructure of weld regions were performed at MSFC. 

The MSFC NDE team also provided acoustic emission

test support. Photogrammetric techniques to measure 

vessel deformations on an LPV not in service were 

conducted at GRC. Some phased array ultrasonic 

technique (PAUT) NDE development was done in 

coordination with MSFC, SSC, and LaRC.

In the end, several near-term and long-term recommendations were identified. Near-term recommendations 

could be implemented immediately, such as inspecting 

vent holes to ensure they aren’t blocked or corroded; 

monitoring for product loss, which could indicate an inner 

shell failure; imposing service restrictions; implementing 

physical barriers; and developing a standard Agency 

process for LPV usage and centralized information 

database. 

Long-term recommendations included extensive materials testing and the development and validation of 

analysis methods and NDE techniques to address highrisk conditions. The assessment revealed that the PAUT 

technique holds promise for inspecting specific LPV 

welds. 

While simply replacing aging LPVs would eliminate the 

most risk, the cost and schedule impact would soar into 

the billion dollar range, Prosser said. “It’s a problem we’re 

not going to immediately take care of by replacement. 

We’ve got to better understand these vessels to manage 

our risks effectively.” Government and industry users of 

LPVs are already requesting copies of the assessment 

results. “They were very interested in learning from our 

experience,” he said. 

Working together with the NASA pressure systems 

managers as well as experts in materials, inspection, 

and structural analysis from the NESC Technical 

Discipline Teams, Prosser said the insight gained during 

the assessment was invaluable. “It was certainly a 

challenge,” he acknowledged, “but the opportunity to 

learn about critical engineering issues, new technologies, 

and applications is always fun.” □

Reference NASA/TM-2014-218505

Shell liner

Vent hole

Layers

Weld

Tank 

head

A brief history of LPVs

The LPV fabrication method was developed 

in the 1930s. As the need grew to hold liquids 

and gases at higher pressures, thicker-walled 

vessels were required, but building vessels from 

a single, thick plate of steel became difficult. 

Manufacturers discovered that high-strength 

thin steel plates had better material properties, 

could be easily rolled, and were less expensive 

to fabricate. These thin sheets were layered 

together and welded, creating an LPV that could 

withstand pressures up to 10,000 psi. While 

fewer than 24,000 LPVs have been fabricated, 

a number of known catastrophic failures have 

occurred in both code and non-code vessels.

About PAUT

Circumferential shell-to-head welds, which join 

the LPV domed single layer tank head to the 

cylindrical layered body, are of particular interest, 

since the area can develop cracks, which has 

led to catastrophic failure. PAUT inspection 

offers advantages over conventional ultrasonic 

inspection techniques. A phased array ultrasonic 

probe contains a number of elements that each 

emit an ultrasonic wave. By electronically varying 

the timing of the excitation of the different 

transducer elements, the resulting ultrasonic 

beam can be “steered” in different directions. This 

approach indicated the shell layers intersecting 

the shell-to-head weld region had a number of 

flaws in a test vessel.

More than 300 layered pressure vessels (LPVs) are in operation at NASA facilities across the country. Gases 

such as helium, hydrogen, methane, nitrogen, and air are 

stored under high pressure in these LPVs and supply a 

variety of NASA test facilities like wind tunnels and engine 

test stands. The vessels vary widely in size and operate 

under a broad range of pressures and temperatures, but 

they all share one common denominator: age.

Past the 50-year mark

Built in the 1950s and 1960s, many have passed 

the 50-year mark and are now at risk for age-related 

concerns. “You start to worry about things like fatigue, 

cracks, corrosion, environmental degradation, and 

embrittlement,” said Dr. William Prosser, NASA Technical 

Fellow for Nondestructive Evaluation (NDE). Also built 

prior to the inclusion of LPV construction methods in 

American Society of Mechanical Engineers boiler and 

pressure vessel codes, they are at a higher risk as “noncode” vessels. 

To ensure the continued safe operation of LPVs at NASA, 

the NESC established a team of experts from across 

NASA Centers to develop a proposal for test and analysis 

methods to keep age-related concerns in check, a task 

made more difficult by the LPV design itself. “Because 

of this layered structure, it’s hard to see into the layers to 

detect flaws in the welds,” said Prosser. 

Establishing consensus on a plan forward was a top 

priority. “Every Center had a different level of background 

and understanding of the nature of the problem, had tried 

different methods, and had different perspectives on 

what should be done,” Prosser noted. 

 

Assessing the future of LPVs

As for the LPVs themselves, many weren’t originally built 

for NASA, but for the Department of Defense or other 

government entities, which meant little or no information 

existed on vessel history – how they were used, pressures 

they were subjected to, or materials they once contained. 

The assessment began with reviewing any available 

inventory information, like manufacturer, age, condition, 

rated and operating pressure, contents, layer thickness, 

12

Section of weld between layered tank cylinder 

and single layer tank head (top) with cut-away 

illustration (bottom).

Typical large facility layered pressure vessels can be pressurized to 5,000 psi. 

13

featured knowledge

Under Pressure:

LPVs Feeling the Effects of Age 
Reaction wheels

Control thruster

High-gain 

antenna

Star trackers

Solar 

array

technical interchange meeting (TIM) to evaluate those 

ideas. Today, after the successful development of a new 

two-wheel/thruster hybrid controller by the spacecraft’s 

prime contractor, Kepler is once again collecting valuable 

science data. 

“Initially it looked like the Kepler Mission was done,” 

said Dennehy. “But the project team and the GNC 

community felt something could be done to regain 

three-axis attitude control. We used the pointing TIM 

as a forum for the project to hear and evaluate a wide 

variety of hybrid control ideas from the community that 

could potentially help accomplish new types of Kepler 

science observations. It was a real group effort to get 

Kepler back on the air, pointing sufficiently to perform 

science. Collectively we were able to accomplish that, 

and that’s a big deal. Kepler isn’t collecting exactly the 

same science data as it was originally, but it’s doing some 

very scientifically valuable observations.” 

The future of hybrid control

Following Kepler’s success, research continues at the 

Naval Postgraduate School, under NESC sponsorship, to 

evaluate nonlinear hybrid attitude control concepts, ideally 

for Kepler, but which may have broader applicability to 

other NASA under-actuated spacecraft. These concepts 

would work without the use of propellant-consuming 

thrusters, employing only the two remaining functional 

wheels. 

In the near future, Dennehy envisions a second workshop 

to continue efforts in developing hybrid ACS techniques. 

“Hybrid attitude control has a background that dates 

back more than a decade, and it is still a dynamically 

evolving area of research and practice,” he said. “This is 

the kind of challenging problem a GNC engineer likes to 

work on.” □

Reference NASA/TM-2014-218539

The NESC’s Guidance, Navigation, and Control (GNC) Technical Discipline Team (TDT) is sharply focused 

on the development of hybrid attitude control approaches 

and techniques for NASA spacecraft. The necessity for 

such hybrid techniques has grown in the last several 

years as science spacecraft, some working in extended 

mission operations, have been rendered nonfunctional or 

placed in jeopardy after crippling reaction wheel failures. 

“Failures have occurred both before and after primary 

mission completion,” said Mr. Neil Dennehy, the NASA 

Technical Fellow for GNC. “Fortunately, many project 

teams were able to successfully develop and implement a 

hybrid attitude control scheme, using both the remaining 

functional wheels and the thrusters. This allowed these 

spacecraft to continue in a scientifically productive mode 

using nonstandard mixed-actuator techniques to obtain 

three-axis control with only two wheels.” 

The story of hybrid control

The challenge in implementing hybrid attitude control, 

said Dennehy, is manipulating the physics of an underactuated space vehicle, harnessing the remaining attitude 

control actuators, and often exploiting naturally occurring 

disturbance torques. “The project teams that have faced 

the challenges of dealing with failed reaction wheels have 

responded with clever and implementable solutions for 

hybrid attitude control. What they accomplished is a 

great feat of engineering and flight operations innovation,” 

Dennehy said. The end result is a restructured, but 

effective, configuration and operating mode for these 

spacecraft, though one likely not envisioned by the 

designers of the original attitude control system (ACS). 

With billions of dollars invested in spacecraft assets, 

which are collecting invaluable science data, the need 

to keep those spacecraft operational for as long as 

possible, in today’s economic climate, is a clear-cut goal. 

“NASA has a history of trying to squeeze more and more 

out of its science spacecraft,” said Dennehy, putting the 

development of successful hybrid ACS at the top of the 

GNC “to do” list. 

Since reaction wheel problems began emerging in 2001, 

efforts have been underway to address the issue. In early 

2007, NASA formed a tiger team to investigate the wheel 

anomalies and failures occurring on spacecraft, and in 

spring 2013, the NESC sponsored a NASA workshop 

on Hybrid (Mixed-Actuator) Spacecraft Attitude Control, 

gathering key personnel from across NASA Centers and 

industry for a 2-day delve into contingency spacecraft 

attitude control techniques.

At the workshop, discussions revolved around previously 

successful hybrid control techniques developed by 

the ACS teams for spacecraft such as Far Ultraviolet 

Spectroscopic Explorer (FUSE) and Thermosphere, 

Ionosphere, Mesosphere, Energetics and Dynamics 

(TIMED). Brainstorming sessions were held to tackle 

current issues faced by Kepler, Dawn, and Mars Odyssey 

spacecraft. 

Seven different spacecraft were discussed at the 

workshop, and Dennehy said that the range of hybrid 

control implementation challenges was just as varied. 

What they quickly discovered was that a mission’s 

operational requirements, a spacecraft’s physical 

configuration, ACS architectures, and more, all play 

a huge role in the development of a successful hybrid 

approach. As presentations and discussions ensued, a 

revealing list of lessons learned emerged, some of which 

came into play sooner than expected. 

Extending the Kepler Mission

Not long after the workshop, Kepler suffered the loss 

of a second reaction wheel, leaving the spacecraft with 

only two operational wheels. After issuing an open 

call seeking innovative hybrid attitude control ideas for 

possible application in repurposing Kepler for new science 

objectives, the NESC coordinated a spacecraft pointing 

DAWN

Mars Odyssey

Kepler

14 15

featured knowledge

Tackling Hybrid Control is

Right in the GNC Wheelhouse
The James Webb Space Telescope (JWST) will be the 

world’s largest infrared, space-based observatory. 

It features a more than 21-foot primary mirror and is 

expected to launch in 2018. A successor to the wellknown Hubble telescope, JWST will be able to see 

back to the beginnings of the known universe, the 

earliest formation of galaxies, and the birth of planetary 

systems. To allow JWST to look back in time, the software 

development team at GSFC took an integrated computeraided software engineering (CASE) approach to design 

the complex software. The team employed a modern 

suite of modeling and development tools based on the 

Unified Modeling Language (UML). 

Enhancing systems integration

Two critical systems, the integrated science instrument 

module (ISIM), which integrates all the hardware and 

software to support the JWST science instruments, and 

the core command and data handling (C&DH) software, 

were developed this way, as were all the applications 

controlling the specific science instruments. “The use 

of an integrated CASE tool suite for development was 

primarily to reduce the complexity of integration of all 

the independently developed instrument software,” said 

Mr. Michael Aguilar, NASA Technical Fellow for Software. 

Several NASA Centers, along with partners from industry, 

academia, and the European Space Agency were involved 

in the software development at their individual facilities, 

following their own review processes.

Standardized development tools 

The project team standardized the use of IBM’s Rational 

Rose CASE tool for the JWST software design, coding, 

testing, as well as integration. Taking full advantage of the 

tool, “The ISIM Flight Software Development Team was 

one of a few organizations in the high reliability spaceflight 

environment to use the tool’s auto-source code generation 

aspects,” Aguilar added. The team coded within the UML 

Continued on next page

About Kepler 

Launched in March 2009, the Kepler spacecraft 

was tasked with performing a photometric survey of 

approximately 100,000 stars in a section of the Milky Way 

near the constellation Cygnus. Its mission was to detect 

planets and determine the prevalence of Earth-sized 

planets in or near the habitable zone. Planet detection 

required Kepler to maintain a pointing stability of better 

than 9 milliarc-seconds for science observation periods 

longer than 30 minutes. 

Near the end of Kepler’s 3.5-year prime mission, a 

reaction wheel failed when its friction increased beyond 

the attitude control law’s torque command. A second 

wheel was lost in May 2013, which prompted the Kepler 

Project to request support from the NESC GNC TDT and 

spurred the development of a two-wheel hybrid controller 

at Ball Aerospace (the Kepler prime contractor). A known 

challenge, GNC engineers at Jet Propulsion Laboratory 

had already conducted a hybrid control feasibility study 

that showed achieving Kepler’s original long-term pointing 

stability with only two wheels would be unlikely.

In parallel with Ball Aerospace, members of the GNC TDT 

independently worked to analytically demonstrate the 

feasibility of a bias-momentum hybrid control approach 

for Kepler. Results obtained by Ball engineers and the 

GNC TDT compared favorably, and the new Ball-designed 

two-wheel/thruster hybrid controller was implemented on 

the repurposed Kepler observatory, called K2. 

K2 is now successfully collecting science data using this 

hybrid attitude control. The momentum bias, created 

by the combination of the two remaining wheels, will be 

oriented normal to the Kepler spacecraft’s orbital plane 

so targets in that plane can be tracked by modulating the 

bias. K2 will be pointed in the ecliptic plane to exploit the 

solar radiation pressure disturbance torque rather than 

fight it. In December 2014, the K2 mission logged its first 

exoplanet discovery of a planet 2.5 times the diameter 

of Earth, named HIP 11645b, proving K2 is once again 

performing valuable science.

Reaction wheel basics

Reaction wheel (RW) technology provides spacecraft 

attitude control torque and momentum management 

functions. RWs rotate the spacecraft and are frequently 

used for stabilizing, slewing/orienting, and precision 

pointing spacecraft platforms. Typical RW actuators 

consist of a rotating inertia flywheel, a wheel suspension 

system (almost exclusively lubricated bearing balls), a 

wheel drive motor, and wheel drive electronics encased 

in a wheel housing/enclosure. RWs are used in Earth 

and Mars orbiting spacecraft as well as on interplanetary 

vehicles, with a typical complement of four RWs providing 

a redundant three-axis attitude control capability. While 

the failure of one RW can typically be managed, the 

failure of two wheels poses a significant challenge for 

accomplishing some form of three-axis attitude control.

Top five takeaways for hybrid control

No one hybrid solution is applicable to all spacecraft, 

but some key lessons learned are applicable to all ACS 

hybrid design.

1. While successful hybrid (mixed actuator) ACS techniques have extended the science productivity of 

several NASA spacecraft, prelaunch considerations 

for implementing hybrid attitude control were nearly 

non-existent. ACS architectural considerations early 

in system development may facilitate hybrid control 

implementations in the later stages of mission life.

2. There are advantages to considering a bias-momentum 

approach when designing a two-wheel-based hybrid 

control system, as was successfully implemented on the 

repurposed Kepler. 

3. Spacecraft fault management/safing/safe mode as

pects should be carefully considered when designing 

new hybrid control modes.

4. Maintaining ACS flight software testbeds whenever 

possible will aid in flight readiness recertification efforts in 

the face of wheel in-flight anomalies. 

5. On-orbit testing of spacecraft attitude controllers in 

hybrid ACS configurations, especially near the end of life, 

is wise and will likely benefit future spacecraft missions. 

TIMED

FUSE

The first 6 of 18 segments that will form the James Webb Space Telescope primary mirror.

Ball Aerospace

16 17

Preparing to See into the Past

featured knowledge featured knowledge
rtUbound

registerModeLog

deleteOneCapsule restartOneCapsule

resetCounters

resetCounters

S2

normalMode

sendResetData

True

CP2

C

C

False

rtPortBounds

hsInitCompleted

dumpModeLog

eepromCrcReq

noEEpromCrc

scReady

nvReady

waitForCrcNvResp

H* H*

H*

H* H*

H*

H*

H*

Ccdh_StartupInitialization

make is

controlled

by a

makefile

1. Rational Rose

RealTime invokes

external

Generate/Compile

2. Make 

invokes

compiler

3. Compiler

compiles

C source

files ...

UNIX: Top

Win32: Top.exe

make/n make

Executable

C compiler

makefile

C

source files

RTS

Library

4. ... and 

links with RTS 

Library

5. The result is 

an executable 

program

Scope of this Porting Guide

make is

controlled

by a

makefile

Model-Based Systems Engineering (MBSE)

MBSE is a formalized methodology for 

implementing the processes and practices of 

systems engineering through the use of models 

and modeling. In practice, it is the application 

of modeling to support system requirements, 

design, analysis, verification, and validation 

activities beginning in the conceptual design 

phase and continuing throughout development 

and later life cycle phases. MBSE encompasses 

requirements, behavior, architecture, and the 

validation and verification in one system-level 

model, regardless of hardware or software 

implementation.

Model-based engineering has been practiced 

for years in discipline-specific areas. Examples 

include computer-aided design for developing 

two or three-dimensional models of physical 

objects, finite element models to examine the 

physical behavior and response of structures, 

and electronic circuit simulation tools to 

examine circuit performance are just a few 

examples. Current MBSE efforts are working 

to incorporate the discipline-specific models 

into the system-level model for increased 

accuracy of system-level performance 

predictions. To deal with the rise of softwareintensive systems, a new concept of designing 

software was introduced in the ‘70s, called 

computer-aided software engineering (CASE). 

This term is used for a new generation of tools 

that applies rigorous engineering principles 

to the development and analysis of software 

specifications, which have now evolved to 

cover the complete software engineering 

lifecycle process. The term integrated 

computer-aided software engineering (I-CASE) 

was introduced and includes tools capable of 

generating entire executable applications from 

design specifications.

These new methodologies enable rapid 

prototyping techniques to develop systems 

faster, at lower cost and higher quality. By 

using a prototype, the developed system 

can be tested more often in between the 

development phases. Design decisions can be 

validated, and design errors can be detected 

and corrected early in development to produce 

systems more efficiently and effectively. □

design model elements, ensuring code and design were 

always in sync, significantly increasing productivity as 

design and code reviews no longer required resourceintensive review material preparation. 

A built-in software documentation tool and document 

templates were used for automated creation of code 

and design review documentation using model elements 

and database contents. The IBM Rational Requisite 

Pro tool suite was used for requirements management. 

Requisite Pro was part of the integrated tool suite that 

provided links to the configuration management and 

defect tracking tools and enabled traceability down to 

the source code implementation levels. “The tools helped 

facilitate concurrent development by the multi-developer 

teams,” Aguilar noted.

Accruing benefits

The ISIM Ground System Support Team delivered more 

than 21 commercial-off-the-shelf-based development, 

test, and integration systems to validate and qualify 

flight instrument hardware for space. ISIM flight software 

was used to qualify flight hardware for space through 

formal box-level environmental testing, test procedure 

development and operator training, and to develop and 

certify operational scripts for spaceflight use. “The cost 

and effort in the development and maintenance of these 

test systems paid off when the effort of integration of all 

the software completed within 1 week of delivery,” said 

Aguilar.

The code generated by the CASE tool was found to be 

acceptable for the mission. The compiled code passed 

unit, subsystem, and system testing in an environment 

identical to previous mission testing environments. Static 

code checkers performed source code analysis to ensure 

specific standards were being followed, coding language 

issues were addressed, and coding errors were identified.

Over the course of the project, about 25 software build 

cycles were required for the ISIM and C&DH code, 

with each build encompassing a feature that could be 

functionally tested. Each software build was verified with 

a build integration test quality check before being passed 

to the test team, which performed an independent 

functional build verification test in parallel with the next 

software build. Similar build cycles occurred across the 

partner teams developing the science instruments. This 

overlapping schedule continued until all required features 

were implemented.

Ultimately, the choice of a common set of development 

tools and incremental and iterative software development 

processes could respond to changes in requirements 

rapidly and fit into the NASA system-level project waterfall 

requirements and schedule. □

Software development environment provided by IBM’s Rational Rose CASE tools. Example of UML statechart used on JWST for state machine modeling.

18 19

featured knowledge featured knowledge
To carry astronauts beyond near Earth orbit to 

rendezvous with asteroids, the Moon, or Mars, the 

Orion Multi-Purpose Crew Vehicle (MPCV) must be as 

light as possible, and spacecraft engineers are always 

looking for ways to “take mass” out of a design. Weighing 

in at over 3,000 pounds and just over 16 feet in diameter, 

the Orion crew module (CM) heat shield carrier structure 

offered the best opportunity to shave off a bit of weight 

– about 800 pounds in fact, or 25% of its mass. While 

the Orion MPCV Team worked hard to reduce mass in 

this area, the Orion MPCV Chief Engineer requested the 

NESC study the heat shield carrier and develop alternate 

designs to the structure.

The carrier structure must hold the thermal protection 

system heat shield securely to the Orion CM while facing 

launch, reentry, and splashdown impact loads, including 

4,800° F reentry temperatures. Its baseline construction, 

made of titanium and composite carbon graphite skin to 

hold the Avcoat ablator thermal protection system, was 

an agile design that could be easily manipulated and 

changed, but the Orion MPCV Program needed to know 

if it was the most mass-optimum design.

Mr. Michael Kirsch, NESC Deputy Director who was then 

an NESC Principal Engineer, led the NESC assessment 

team that included members from industry, contractor 

partners, and NASA Centers including JSC, GSFC, LaRC, 

and MSFC. The team developed several alternative 

concepts, including designs that incorporated load 

sharing with an H-beam configuration, and switched the 

composite carbon graphite skin to a titanium orthogrid 

skin. By down-selecting to the titanium orthogrid option, 

the team had already saved over 1,000 pounds. The design 

was developed by processing thermal, aerodynamic, 

and water landing loads through finite element models 

of the titanium orthogrid structure. The team designed, 

built, and tested a 20-inch-diameter subscale heat shield 

orthogrid test article and visited titanium forging facilities, 

electron beam welding facilities, and large-scale titanium 

machining facilities to improve confidence that the final 

design solution could be manufactured.

The final NESC design was estimated to save about 

1,600 pounds over the baseline, far exceeding the original 

goal of 800 pounds. Encouraged by the NESC team’s 

weight savings, the Orion CM baseline design had been 

undergoing revisions and had significantly reduced its 

mass, eliminating about 1,100 pounds.

The Orion MPCV Program ultimately stayed with its 

composite carbon graphite design, versus the titanium 

option proposed by the NESC for several reasons. 

While weight savings were a significant factor in design 

selection, so was schedule. Orion’s first exploratory 

mission is expected in 2017, and the NESC design required 

financial commitments for material procurement and 

manufacturing and had a tight schedule for construction. 

Further, the baseline design had already demonstrated 

the full-scale manufacturing process, which lowered 

manufacturing risks, nonrecurring financial commitment, 

and a shortened delivery timeline.

Even though the NESC’s alternative design was not 

selected by the Orion MPCV Program, it promoted the 

aggressive redesign of the current baseline and the net 

result was a significant reduction of overall mass. □

20

Successful launch of the Orion Multi-Purpose Crew

Vehicle on the Delta IV Heavy for Exploration Flight Test-1.

Far Left: Proposed 

titanium orthogrid 

heat shield carrier 

mounted to crew 

module pressure 

vessel.

Left: Heat shield 

carrier structure (top) 

and corresponding 

lower portion (bottom)

of pressure vessel 

with “H-beamˮ

backbone interface 

structure.

featured knowledge

An Alternate Orion Heat Shield

Carrier Structural Design
The third revision of ALAS 11 made the final cut with 

the Orion MPCV Program and became the baseline 

configuration for the LAS design. Though other designs 

had higher performance improvements, ALAS 11 

was a good compromise that offered considerable 

aeroacoustic load relief. “That’s the one that could 

fly without fins, yet remain controllable, and offer 

aeroacoustic protection and aerodynamic benefit. It was 

also relatively easy to incorporate,” said Schuster. Wind 

tunnel testing confirmed the ALAS-11 had the best blend 

of aerodynamic and aeroacoustic performance with the 

required launch abort vehicle stability characteristics.

In parallel to the development of ALAS, the NESC was 

also pursuing a towerless LAS, known as the Max 

Launch Abort System (MLAS), to tackle development 

challenges with regard to the tower design on the Orion 

MPCV. While those challenges were later overcome, 

the MLAS, based on the new ALAS shape, pushed the 

boundaries of the LAS design even further. 

ALAS proven on EFT-1

Ultimately, ALAS offered benefits beyond what was 

expected and in December 2014, ALAS successfully 

flew for the first time on EFT-1. “Something that was 

effectively a research study became the baseline — the 

main geometry — for the Orion vehicle,” said Schuster, 

who didn’t realize back in 2006 that ALAS would help 

redefine the concept of the LAS at NASA. Since timing 

of the ALAS development didn’t mesh with either the 

ARES 1-X test flight or the first pad abort test for the 

Orion MPCV Program, “The Orion EFT-1 was the first 

time flying with the ALAS design,” Schuster said. This 

would finally allow the Orion MPCV Program and the 

NESC team to collect and analyze real-time flight data 

on the new configuration. It was a big moment for 

everyone involved, he said. “We could point to the top of 

the vehicle and say ‘We designed that shape.’” □

I

n December 2014, NASA’s Orion 

Multi-Purpose Crew Vehicle 

(MPCV) Program successfully 

conducted Experimental Flight 

Test-1 (EFT-1), the first orbital flight 

test of the Orion spacecraft. Close 

observers may have noted that the 

spacecraft had an updated shape 

from the concepts included on the 

previous Ares I-X and Orion Pad 

Abort 1 flight tests. In reality, the 

Orion crew module (CM) shape has 

not changed substantially since 

these flights, but the Orion Launch 

Abort System (LAS) has changed.

Reducing structural loads

In September 2006, during a peer 

review of the NESC Composite 

Crew Module (CCM) Assessment, 

an Alternate Launch Abort System 

(ALAS) was conceived to reduce 

structural loads carried by the 

CCM during a flight abort. To 

further investigate the feasibility 

of the ALAS concept, Dr. Charles 

Camarda (then NESC Deputy 

Director for Advanced Projects) 

sponsored a study to evaluate 

promising approaches to improve 

overall Orion CM mission 

performance. This short, 5-week 

effort developed the concept of a 

multifunctional boost protective 

cover (MBPC) for the Orion CM, 

with analyses that demonstrated 

a system mass reduction due 

to the improved load transfer 

characteristics of the ALAS 

concept. An additional benefit the team discovered, which 

was not initially anticipated, was that the aerodynamically 

contoured forward fairing over the CM significantly 

reduced the overall launch vehicle drag – so much that 

the reduced drag provided even more payload-to-orbit 

increase than the improvement in structural load path.

Additional ALAS benefits investigated

Based on the promising phase 1 results, the NESC 

extended the effort designating Dr. Stephen Scotti, ALAS 

phase 1 lead, and Dr. David Schuster, NASA Technical 

Fellow for Aerosciences, to co-lead a second phase 

of the ALAS study team to further refine the concept. 

Starting in December 2006, 

they performed aerodynamic, 

structural and controls analyses, 

as well as a number of wind tunnel 

experiments, to obtain the data 

required to validate the concept.

“We found that adding a fairing 

improved the aerodynamic shape 

significantly,” said Schuster. “It 

reduced drag during ascent, as well 

as weight by providing a separate 

load path around the crew module.” 

In addition to better quantifying 

the aerodynamic, performance, 

and structural improvements, 

a major new focus investigated 

using the ALAS MBPC to reduce 

aeroacoustic loads on the Orion 

CM. “Current predictions of Orion 

acoustic loads far exceeded what 

was assumed in the design of the 

Orion subsystems,” said Scotti. 

“And the project hoped that the 

ALAS approach would help solve 

that problem and eliminate the 

need to redesign and requalify all 

the subsystems.”

The team developed a suite of 

aerodynamic shapes for the 

MBPC from a simple conic that 

would be easy to manufacture 

to the final Sears-Haack fairing 

offering the greatest drag 

reduction. A diverse family of ALAS 

configurations were evaluated 

using high fidelity computational 

fluid dynamics simulations 

in concert with wind tunnel 

testing. In total, 11 ALAS designs were evaluated along 

with 10 revisions to the 11th ALAS concept. Each 

design offered its own level of performance, stability, 

and acoustic advantages, but there were tradeoffs.

For example, improvements in performance in some of the 

designs added additional complexity with the addition of 

fins and ducted abort motors. “The combination of high 

fidelity fluid dynamics analyses and the wind tunnel tests 

was essential to the design process because it positively 

identified the sources of noise in the flow” said Scotti.

“We didn’t have that capability during Apollo. Now instead 

of blindly trying design modifications, we knew exactly 

what changes would help and where to make them.”

22

Unpainted ALAS fairing used to 

protect the Orion crew module during 

Exploration Flight Test-1.

Mercury and Apollo spacecraft used launch abort towers without 

aerodynamically and structurally beneficial fairings.

Lockheed Martin

Above: ALAS fairing mounted atop a United 

Launch Alliance Delta IV Heavy Rocket for the

EFT-1 launch. Below: After developing the ALAS 

shape, the NESC performed further testing in 

the ARC Unitary Plan Wind Tunnel to investigate 

stability augmentation provided by grid fins.

Reference NASA/TM-2014-217155

featured knowledge

Changing the Shape

of Launch Abort Systems
Acritical component of crewed spacecraft, the launch 

abort system (LAS), allows for rescue of the crew in the 

event of a catastrophic malfunction while the spacecraft 

is sitting on the launch pad or on its way into orbit. For 

a successful rescue, however, the LAS must perform 

several critical maneuvers in rapid-fire succession. First, 

the launch abort motors must be powerful enough to fly 

the fairing and crew module (CM) to a safe distance away 

from the launch vehicle. Next, it must reorient and fly in 

a carefully controlled heat shield-forward attitude. Finally, 

it must release the CM, enabling the CM’s parachute 

landing system to deploy for a safe return of the crew.

LAS begins with Project Mercury

Since the time of Project Mercury and the Apollo 

Program, the LAS has maintained its traditional tower 

configuration. But as spacecraft design has evolved, so 

has the need for a new LAS. The Orion Multi-Purpose 

Crew Vehicle launched on December 4, 2014, featured 

a new Alternative Launch Abort System (ALAS) shape 

and structure that enhanced the aerodynamic and 

aeroacoustic performance of the spacecraft. But while 

the NESC was spearheading efforts on the ALAS design, 

it was also developing the Max Launch Abort System 

(MLAS), a follow-on to the ALAS design that incorporated 

the ALAS shape while fundamentally changing the LAS 

from a tower to a towerless design.

Named in honor of Maxime Faget, developer of the original 

Mercury launch escape system, MLAS was a 2-year effort 

that culminated in a full-scale flight demonstration. The 

initial goal of MLAS was to keep the ALAS advantages 

while pursuing a LAS concept that eliminated the tower 

and did not require active attitude control or stabilization 

following escape motor burnout. A key design constraint 

was avoiding structural changes to the CM if MLAS was 

substituted for the launch abort tower. 

From napkin sketch to flight test

From a napkin sketch design drawn by the NASA 

Administrator at the time, which featured six sidemounted escape motors attached to the service module, 

the NESC team focused on key issues such as the 

number and placement of motors, separation dynamics, 

stability following motor burnout, and CM extraction from 

the fairing. This concept became the basis for the MLAS 

flight test vehicle, which would be boosted to abort test 

conditions to prove MLAS was passively stable, could be 

reoriented with parachutes, and safely release the CM 

for crew recovery. Launched from NASA Wallops Flight 

Facility in July 2009, the MLAS successfully demonstrated 

all flight test objectives.

During the flight test, dummy motors were incorporated 

into the MLAS fairing alongside the CM. This preserved 

space for the next flight test concept, which was to use 

the six abort motors with thrust vector control to perform 

active stabilization and eliminate the large exterior fins 

used on the first flight test. Thrust vector control would 

allow the MLAS to steer in the best direction for safety 

during the boost phase of an abort, then reorient for safe 

release of the CM. This MLAS objective system design 

was completed to a point where it could be built and 

tested if needed in the future.

More than 150 people from across NASA, as well as 

industry partners, had a hand in bringing the MLAS flight 

test to fruition, not only meeting the mission objectives, 

but developing and building a full-scale prototype vehicle 

from which invaluable experience was gleaned for future 

NASA projects. □

24

Machining of orthogrid pattern into tank shell at 

MSFC to be used for test factor in the NESC Shell 

Buckling Knockdown Factor Assessment.

Propulsively stabilized MLAS concept.

Left: Successful launch abort test of the passively stabilized 

MLAS flight test vehicle. Right: Spent test booster can be seen 

falling away after launch.

Launch Abort System Evolution

featured knowledge
SPACE OPERATIONS

EMU Lithium-Ion Battery Assessment

The International Space Station (ISS) Program Manager 

requested the NESC perform an independent review 

of the ISS Extravehicular Mobility Unit (EMU) long-life 

batteries (LLB). The NESC performed an LLB review in 

2009, however, recent issues with commercially used 

lithium batteries led to the additional review request. 

NASA/TM-2014-218164

MMOD Design and Analysis Improvements

The NESC identified the need to address ways to improve 

micrometeoroid and orbital debris (MMOD) protection 

and analysis highlighted by previous NESC assessments. 

NASA/TM-2014-218268

ISS ORU Wet Storage Risk Assessment

The ISS Program Chief Engineer’s Office requested the 

NESC evaluate the risk of storing ISS orbital replaceable 

units (ORU) that have been serviced with deionized water 

for long periods of time (years) before being used on orbit. 

NASA/TM-2014-218172

ISS PCU Utilization Plan Assessment Update

The ISS Systems Manager for Space Environments 

requested the NESC extend a previous assessment to 

include additions to the ISS plasma contactor unit (PCU) 

utilization plan. The previous assessment investigated 

whether leaving PCUs off during non-extra-vehicular 

activities presented any risk to the ISS through assembly 

completion. NASA/TM-2014-218512

Review of ESD Integrated

Hazard Development Process

The Exploration Systems Development (ESD) Chief 

Engineer requested the NESC perform an independent 

assessment of the ESD integrated hazard development 

process, focusing on a review of the integrated hazard 

analysis process and identifying any gaps/improvements. 

SLS Block I Booster

Insulation Characterization

The SLS Booster Element Manager requested the 

NESC address specific, identified weaknesses in the 

fundamental understanding of SLS Program Block I 

five-segment reusable solid rocket motor polybenzimidazole insulation age life and material performance.

Flight Testing of the SLS

Launch Vehicle AAC Algorithm 

The MSFC Flight Mechanics and Analysis Division 

requested the NESC partner with the SLS Program 

and the Space Technology Mission Directorate Game 

Changing Development Program to flight test the adaptive 

augmenting control (AAC) algorithm on a manned aircraft 

to raise the technology readiness of the algorithm. The 

MSFC-developed AAC algorithm was baselined as part 

of the SLS flight control system. NASA/TM-2014-218528

A Comprehensive Analysis of

the X-15 Flight 3-65 Accident

Draper Laboratory performed an analysis to investigate 

the role of the MH-96 self-adaptive flight control system 

in the fatal accident of an X-15 vehicle in November 1967. 

As the AAC is part of the baseline SLS vehicle flight 

control system, a comprehensive analysis was necessary 

to understand the causes and evolution of the accident 

to reduce risk to emerging aerospace vehicle concepts. 

NASA/TM-2014-218538

EXPLORATION

Spin Forming Aluminum Lithium

CM Metallic FPVBH

The NESC explored producing a single-piece crew 

module (CM) forward pressure vessel bulkhead (FPVBH), 

integrating the forward bulkhead, cone, and barrel 

into a single component. The spin forming fabrication 

method could simplify FPVBH fabrication and enhance 

CM design. The work addressed key attributes of the 

single-piece pressure vessel design that would be 

relevant to produce a full-sized, optimized single-piece 

demonstration FPVBH. NASA/TM-2014-218163 

Spin Forming CM Pressure

Bulkhead Phase II, Aft Bulkhead and Cone

The Multi-Purpose Crew Vehicle (MPCV) Chief Engineer 

requested the NESC assist in developing a spin forming 

fabrication process for the manufacture of the Orion CM 

aft pressure vessel bulkhead and cone. The spin forming 

process will enable a single piece aft bulkhead and single 

piece cone versus multiple-piece welded construction, 

simplify CM fabrication, and lead to an enhanced design.

CPAS Wake Deficit Wind Tunnel Testing 

The Orion MPCV Chief Engineer requested the NESC 

acquire flowfield measurements of the wake behind the 

Orion MPCV capsule in subsonic and transonic flight 

conditions to support Crew Exploration Vehicle Capsule 

Parachute Assembly System (CPAS) parachute design 

and performance prediction and to also support validation 

of computational fluid dynamics tools. NASA/TM-2014-

218171 

Orion TPS Margin Study (Phase II) 

The Orion MPCV Program requested the NESC provide 

an updated approach for thermal protection system (TPS) 

margin that accounts for material property and thermal 

model uncertainties. The current margin implementation 

of designing to an artificially reduced bondline temperature 

needs to evolve in the interest of mass optimization and 

TPS reliability. NASA/TM-2013-218262

Launch Abort Vehicle

Transonic Stability Augmentation 

The former Constellation Program Flight Performance 

Systems Integration Group requested the NESC support 

in addressing the potential benefits of grid fins for vehicle 

stabilization during transonic abort. NASA/TM-2014-

218522

Transonic Shock Reflections

in SLS Wind Tunnel Testing 

The Space Launch System (SLS) Program requested the 

NESC assist with performing a transonic test at LaRC’s 

Transonic Dynamics Tunnel to determine the effects of 

tunnel-reflected shock waves on SLS aerodynamic loads. 

Previous testing in other tunnels indicated that shocks 

reflected from the wind tunnel walls could be impacting the 

test article and contaminating the measured aerodynamic 

loads. NASA/TM-2014-218269

Review of GSDO Tools for Verifying

Command and Control Software 

The Exploration Systems Development Standing Review 

Board requested the NESC perform an independent 

review of the Ground Systems Development and 

Operations (GSDO) plan for integrating models and 

emulators to create tools for verifying its command and 

control software. NASA/TM-2014-218278

26

X-15

FPVBH manufactured by spin forming.

An SLS model in LaRC’s Transonic Dynamics Tunnel.

27

completed work completed work
SCIENCE

ARM SEP Analysis of Alternatives 

The Space Technology Mission Directorate requested 

the NESC lead an independent analysis of alternatives of 

the solar electric propulsion (SEP) component proposed 

for the Asteroid Retrieval Mission (ARM) by reviewing the 

underlying assumptions used in the study and examining 

alternative methods for achieving mission success. 

NASA/TM-2014-218159

HST System Reliability Review

The Hubble Space Telescope (HST) Program Systems 

Management and Engineering Manager requested the 

NESC evaluate the current HST system reliability model 

to determine if it can be enhanced or replaced with an 

alternate method and/or approach, allowing the HST 

Program to predict the likelihood of performing viable 

science as a function of time. NASA/TM-2014-218161

JWST Sunshield Venting

Analysis Assessment 

The James Webb Space Telescope (JWST) sunshield 

membrane systems engineer requested the NESC provide 

an independent assessment of the venting analysis of the 

JWST sunshield. NASA/TM-2014-218173

Review of SEXTANT and DSAC

Technology Demonstration Projects 

The Space Technology Mission Directorate requested the 

NESC perform an independent assessment of two of their 

technology demonstration projects, Station Explorer for 

X-ray Timing and Navigation (SEXTANT) and Deep Space 

Atomic Clock (DSAC). NASA/TM-2014-218270

OSIRIS-REx TAG

Onboard Navigation Capability 

The Origins Spectral Interpretation Resource Identification 

Security – Regolith Explorer (OSIRIS-REx) Project 

Manager requested the NESC perform an independent 

assessment of the OPNAV Natural Feature Tracking 

hardware/software system being added to OSIRIS-REx 

as the backup guided touch-and-go (TAG) navigation 

solution. NASA/TM-2014-218277

MMS High Voltage Optocoupler Assessment 

The Magnetospheric Multiscale Mission (MMS) fast 

plasma instrument’s dual electron spectrometer (DES) 

sensor had experienced ground failures during integration 

and test, while its dual ion spectrometer (DIS) sensor did 

not. The NESC identified the need to examine the possible 

effects of the circuit differences between the DES and DIS 

instrument applications and examine potential effects of 

part differences. 

Raven Impact on ISS Visiting Vehicles 

The ISS Program Manager requested the NESC perform 

an independent assessment to evaluate the impact of the 

Raven payload experiment’s light detection and ranging 

vision navigation system on ISS visiting vehicles during 

proximity operations.

ISS ETCS Loop A PM

Jettison Options Assessment 

After the ISS experienced a failure of the external thermal 

control system (ETCS) Loop A pump module (PM), the 

NESC identified the need to independently evaluate 

jettison options being considered by the ISS Trajectory 

Operations Officer and provide recommendations for 

a safe jettison of the PM working within the minimum 

number of extravehicular activities required to replace the 

PM. NASA/TM-2014-218542

Reverse Polarity Capacitor Installation Anomaly 

on the ISS ExPRESS Logistics Carrier Simulator 

The GSFC Electrical Engineering Division Chief requested 

the NESC evaluate the electrical ground support 

equipment simulator and flight build of the ExPRESS 

(Expedite the Processing of Experiments to the Space 

Station) Carrier Avionics (ExPCA) Experiment Control 

Module to investigate the failure of the ExPCA simulator 

at KSC in October 2012. 

CCP Ascent Abort Model Review 

The Commercial Crew Program (CCP) Program Manager 

requested the NESC perform a peer review of the 

CCP-funded independent abort simulation capability, 

the Generic Abort Simulation Package (GASP). The 

independent GASP simulation tool is intended to provide 

CCP with the means to check and evaluate abort 

simulation products provided by the CCP partners. 

Electronic Components in Safety-Critical 

Avionics Systems 

The CCP Deputy Chief Engineer requested the NESC to 

review reliability analyses methodology and assumptions 

for flight avionics, focusing on the current or planned 

practices of aviation and commercial space providers. 

The goal was to establish boundaries for the impact these 

practices have on overall system reliability metrics.

The Use of COTS Electronic Components 

The ISS System Manager for Space Environments 

requested the NESC compare the suitability and 

possible benefits of alternative approaches for the use of 

commercial-off-the-shelf (COTS) electronic components 

in safety-critical avionics systems intended for use in 

human-rated commercial crew spacecraft. NASA/TM2014-218261

Alternative Software

Programming for Human Spaceflight 

The Office of the Chief Engineer requested the NESC 

determine whether a path forward exists to certify or 

validate alternatively developed software for human 

spaceflight, and if none exists, propose a path forward 

for human spaceflight certification. 

Assessing Risks of Frangible Joint Designs

The CCP Chief Engineer requested the NESC conduct an 

assessment of risks associated with designs of frangible 

joints (FJs). Recent Launch Services Program losses 

attributed to FJs have raised concerns about FJ designs, 

especially those that are zero-fault tolerant. A Phase II 

effort is underway with testing of joint mechanisms.

SPACE OPERATIONS

Continued

28

Instrumenting a frangible joint for testing.

completed work
 1. United States Navy Multi-Stage Supersonic Target 

Assessment

 2. Vehicle Integrated Propulsion Research Experiment 

Impacts on the C-17 Engine-Pylon Interface 

Assessment

 3. Space Launch System Program Booster Element 

Qualification Motor-1 Aft Segment Support

 4. Unplanned/Unintended Event or Condition 

Investigation

 5. Ground Testing to Assess the International 

Space Station Ultrasonic Leak Location Concept 

Assessment

 6. Effects of Humidity on Dry Film Lubricant Storage 

and Performance Assessment

 7. Review of Exploration Systems Division Integrated 

Hazard Development Process

 8. Curiosity Wheel Consultation

 9. Risk Reduction of Orion Crew Module Government 

Furnished Environmental Control and Life Support

10. Subscale Low Density Supersonic Parachute Wind 

Tunnel Test

11. Human Vibration Modeling for the Multi-Purpose 

Crew Vehicle

12. Abort Environments Update for Blast Fragments/

Debris Support

13. International Space Station Extra Vehicular Activity 

Lithium-ion Battery Thermal Runaway Severity 

Reduction Measures Assessment

14. Ground Operations Human Factors Task Analysis 

Support

15. NESC Modeling of Crawler/Transporter, Mobile 

Launcher, and Forcing Functions

16. Peer Review of Space Launch Systems and Orion 

Multi-Purpose Crew Vehicle Programs Modal Test, 

Development Flight Instrumentation, and Dynamic 

Model Correlation Plans

17. Joint Polar Satellite System Micrometeoroid/Orbital 

Debris Assessment

18. International Space Station Anomalies Trending 

Study

19. Orion Crew Module and Commercial Crew Window 

Wavefront Measurement Assessment

20. Composite Overwrapped Pressure Vessel Liner 

Inspection Capability Assessment

21. Technical Support to the Multi-Purpose Crew Vehicle 

Capsule Parachute Assembly System Pendulum 

Assessment Team

22. Support to NASA MagicDraw Cloud License Project

23. Soil Moisture Active Passive Reflector and Boom 

Assembly Deployment Risk Assessment

24. Launch Vehicle Buffet Verification Testing

25. Simplified Aid for Extra Vehicular Activity Rescue 

Battery Assessment

26. Stability and Flight Readiness of the Space Launch 

System Flight Control System with Adaptive 

Augmentation

27. Independent Assessment of the Backshell Pressure 

Field for Mars Science Laboratory Entry, Descent, 

and Landing Instrument for Mars 2020

28. Model of the Space Launch System – Multi-Purpose 

Crew Vehicle – Ground Systems Development and 

Operations Stack on the Pad

29. Support to NASA Standard 5009 Development

30. Stratospheric Aerosol and Gas Experiment-III 

Interface Adaptor Module Subsystem Anomaly 

Support

31. Nonlinear Slosh Analysis Techniques for Launch 

Vehicles Assessment

32. Support for the Ames Research Center Arcjet 

Rectifier Snubber Failure Mishap

33. Robonaut Battery Safety Assessment

34. Portable Fire Extinguisher for International Space 

Station Evaluation

35. Independent Assessment of the Multi-Purpose Crew 

Vehicle Parachute Riser Loads

36. RAD750 Single Board Computer Qualification 

Testing Assessment

37. Support Airborne Observation of Automated Transfer 

Vehicle-5 Reentry

38. Development of a Manned Vehicle Reentry Thermal 

Protection System Damage Assessment and 

Decision Plan

39. Evaluation of the Orbital Debris Engineering Model 

3.0 with Available On-Orbit Assets

40. Implementation of JR-A Methodology into the 

NASGRO/Fracture Analysis by Distributed 

Dislocations Codes to Improve Crack Instability 

Analysis

41. Technical Support for Space Launch System 

Vibroacoustics Plans and Analysis

42. International Space Station Columbus Interface Heat 

Exchanger Thermal Response

43. Layered Pressure Vessel Technical Consultation

44. International Space Station Plasma Contactor Unit 

Utilization Plan Assessment Follow-on

45. Review of Fatigue Cycle-Counting/Fatigue Spectra 

Cycle Counting Methodology

46. Technical Support to Space Technology Mission 

Directorate Brazing Tiger Team

47. Independent Computational Fluid Dynamics Analysis 

of Aero/Reaction Control System Interaction on 

Commercial Crew Provider Vehicles

SCIENCE Continued

NASA Workshop on Hybrid (Mixed-Actuator) 

Spacecraft Attitude Control 

The Science Mission Directorate Chief Engineer requested 

the NESC conduct a workshop on lessons learned and 

current developments in hybrid attitude control mode 

design, test, and operations. Cross-Center lessons 

learned were shared among NASA and industry subject 

matter experts. NASA/TM-2014-218539

Ground Wind Loads Uncertainty

for Mars Insight Lander 

The Insight Project systems engineer requested the 

NESC perform predictions of the ground wind loads on 

the Mars Insight Lander following landing and solar array 

deployment. Winds at the landing location could be as 

high as 75 meters per second and wind loads could 

damage the solar panels and/or flip the vehicle. 

Assessment of Combustion

Instability in BB Motors 

The Sounding Rocket Program Office requested the 

NESC provide technical expertise in combustion stability 

modeling and analysis for its workhorse sounding rocket, 

the Black Brant (BB) motor. The scope of the assessment 

included updating existing combustion stability analyses 

and developing stability predictions for the BB proposed 

propellant. NASA/TM-2014-218160

AERONAUTICS

ACCESS Probing Aircraft

Flight Test Hazard Mitigation

The Alternative Fuel Effects on Contrails and Cruise 

Emissions (ACCESS) Project Integration Manager 

requested the NESC to independently assess the 

Falcon 20 structural failure risk associated with flying in 

the wake of the DC-8 and identify potential flight test 

hazard mitigations. Follow-on work involves independent 

analyses of vortex crossing to corroborate project 

predictions. NASA/TM-2013-217995

GENERAL

NESC Enhanced Melamine

Foam Acoustic Test 

The NESC performed an acoustic characterization 

test program of melamine foam, including testing with 

enhanced designs intended to increase the low frequency 

acoustic benefit. Multiple NASA and industry projects 

could benefit from the tests. NASA/TM-2014-218162 

COPV Stress Rupture

Reliability and NASA CPVWG

The Composite Pressure Vessel Working Group (CPVWG) 

has been working to develop strategies, approaches, or 

methodologies to minimize technical risk for the use of 

composite pressure vessels. This task examined shortfalls 

in the current understanding of composite overwrapped 

pressure vessel (COPV) mechanics, resulting in an NESC 

Technical Bulletin 14-03 describing issues with COPV 

modeling. NASA/TM-2014-218260

CAD Tools to Support

Human Factors Design Teams 

The NESC identified the need to develop a database or 

library of human model behavior primitives, which may be 

used for human factors analyses in launch vehicle design 

trade decisions and requirements verification. Database 

users would include NASA, contractors, and commercial 

partners. 

Evaluation of Agency

Non-Code LPVs

The Office of Safety and Mission Assurance requested 

the NESC formulate a consensus draft proposal for the 

development of additional testing and analysis methods 

to establish the technical validity, and any limitation 

thereof, for the continued safe operation of non-code 

layered pressure vessels (LPV) used at NASA. NASA/TM2014-218505

SOFIA Cryo Helium

Dewar Heat Flux Evaluation 

The Stratospheric Observatory for Infrared Astronomy 

(SOFIA) Project requested the NESC evaluate and 

determine the maximum boil-off rate of the cryo helium 

Dewar after a loss of vacuum jacket thermal protection. 

NASA/TM-2014-218540

Check-Cases for Verification of 

6 Degree-of-Freedom Flight Vehicle Simulations

The NESC identified the need to provide verification of 

common elements of flight vehicle trajectory simulations, 

focusing on generic components of flight simulation 

dynamics. The assessment’s scope generated checkcase data for 6 degree-of-freedom simulation tools, 

including equation of motion and gravity models.

View of DC-8 from Falcon 20.

30

As of December 31, 2014

31

completed work work in progress
National Aeronautics and Space Administration

Instability Cause and Consequence

Analysis and evaluation must be performed of any potential 

source of instability (e.g., propellant slosh, flexible 

structure, or aerodynamics), while flying through periods 

of rapidly changing dynamics. A large body of experience 

has been accumulated regarding successfully flying 

through not only degraded margins, but also relatively

brief periods of linearized model instability. These 

instabilities occur as the flight 

environment and vehicle dynamics 

undergo rapid changes. When 

linearized stability robustness 

margin requirements cannot be 

satisfied, alternative methods 

are then needed to ensure that 

deficient stability margins do not 

present a high risk of losing control 

during the mission.

Best Practices for Flight

Control System Design

FCS designers should consider 

employing non-linear system 

requirements that capture both 

stability and performance aspects. Occasionally, it may 

be necessary to set aside the traditional frequency 

domain gain and phase stability robustness margins in 

favor of another technique. The tried-and-true guideline 

that stability always comes before performance in the 

design process remains the same. However, since real 

flight systems behave in a non-linear manner, “stability” 

should be understood as control of the vehicle never 

being lost while simultaneously achieving attitude control 

performance requirements. 

Consider four complementary recommendations for 

certifying FCS designs with deficient stability margins:

1) Accept some Relaxed or even Negative Stability 

Margins: additional analysis may not be required if a 

stability margin fails the requirement for only a brief time. 

Seek out prior experience with similar configurations and 

conditions.

2) Evaluation of Uncertainties: reassess whether 

the uncertainties input into the analysis are realistic.

In certain cases, the effects of correlated variables 

can be taken into account to reduce the level of

uncertainties used in the analysis. 

3) Checking the Time to Double Amplitude: determine if 

the vehicle will fly through the region of concern before the 

oscillations reach unacceptable amplitudes, in which case 

a relaxed or even negative margin may be acceptable. 

4) Use of Non-Linear Time-Domain Simulations: exploit 

the complete non-linear time-domain models to prove 

that the vehicle exhibits acceptable 

behavior, even with programmed 

test inputs to excite oscillations. 

Additionally, the loop gains and/

or time lags can be adjusted in the 

simulation to evaluate the gain and 

phase stability margins remaining 

from a non-linear perspective.

Historically, some launch vehicles 

have been successfully flown 

with the known threat of slosh 

instabilities. The Atlas-II was 

successfully flown with linearly 

unstable (as viewed from a 

purely linear frequency-domain 

perspective) slosh modes. 

An FCS designer should question the application of linear 

stability requirements and not rely exclusively on the 

frequency domain approaches to verify stable flight. The 

use and application of the frequency-domain synthesis 

and analysis tools must be balanced with the non-linear 

time-domain performance simulation tools and the Time 

to Double Amplitude criteria. 

References

1. NASA/TM-2011-217183, NESC-RP-09-00602 v2.0, 

Independent Review of the Ares-I Control Sensitivity to 

Orion Service Module Tank Slosh Dynamics, Oct. 2011 

2. NASA Document Number: EAM-CEV-09-001, Shuttle 

Ascent and Entry GN&C Stability Verification, Edgar 

Medina (PA-1 Flight Dynamics Team), Jan. 23, 2009

3. NASA/SP–2010–3408, Space Shuttle Entry Digital 

Autopilot, Section 9.0 Lessons Learned, Larry McWhorter 

and Milt Reed, Feb. 2010 

For information contact the NESC at nesc.nasa.gov

Designing for Flight Through Periods of Instability 

The Orion launch abort system successfully flew through 

brief periods of instability. Known instabilities and risks 

were evaluated prior to flight using best practices.

For completeness, it is imperative that Flight Control System (FCS) designers use both complementary 

time and frequency domain techniques to address periods of instability. Use of standard frequency domain

synthesis techniques alone may not always yield an FCS design with sufficient gain and phase stability

robustness margins while simultaneously satisfying performance requirements. 

T NASA Engineering and Safety Center Technical Bulletin No. 14-01 his year the NESC produced three technical bulletins that condense new knowledge and best practices into a one-page, quick and easy read. Links are included to reference 

additional material on the subject. NESC technical bulletins can be found at nesc.nasa.gov.

TB 14-01: Flying Through Periods of Instability

An NESC assessment of the Ares 1 flight control sensitivity to slosh dynamics in the Orion 

service module raised questions for Neil Dennehy, NASA Technical Fellow for Guidance, 

Navigation, and Control (GNC), about stability margins, the degree of conservatism flight 

control system (FCS) engineers put into designs, the linear and nonlinear analysis tools 

they use, and how it all related to safely flying a vehicle through brief periods of control 

instability. As stability is a mantra for GNC experts, Dennehy began capturing what the GNC 

community was learning about stability margins with respect to control instability, resulting 

in this technical bulletin that suggests FCS designers not limit themselves, and look beyond 

the frequency domain approach when designing flight control systems.

TB 14-02:  Aerodynamic Reaction Control System (RCS) Orientation and Jet 

Interaction (JI) Model Validation

A historical perspective on jet interaction prediction issues combined with NESC analysis 

gleaned from a Mars Science Laboratory assessment led to this technical bulletin’s guidance 

on the placement and orientation of reaction control system (RCS) jet thrusters on hypersonic 

entry vehicles.   Dr. David Schuster, NASA Technical Fellow for Aerosciences, concluded 

that taking the proper precautions in the development of an RCS system, paired with 

computational fluid dynamics calculations and wind tunnel testing, yields a more accurate 

view of controllability and the flow characteristics behind those vehicles. 

TB 14-03: COPV Mechanical Model Validation 

When issues surrounding the understanding of composite overwrapped pressure vessel 

(COPV) mechanics surfaced in two previous NESC assessments, Dr. Lorie Grimes-Ledesma 

of the Composite Pressure Vessel Working Group discovered that even with the availability of 

vendor-supplied finite element tools, there was a lack of accuracy in understanding COPV liner 

and composite response. And that lack of accuracy was propagating in subsequent fracture 

and stress rupture analysis. A look back to fundamentals in understanding autofrettage and 

a subsequent correlation study between finite element analysis and measured response on 

COPVs led to this technical bulletin’s best practices for COPV model validation.

32 33

technical bulletins
National Aeronautics and Space Administration

Current Obstacles to COPV 

Mechanical Model Validation

Mechanics models and FEA of 

COPVs developed by manufacturers 

have not always been adequate to 

provide accurate general deformation 

response and to pinpoint areas of 

stress concentration in the composite 

shell and liner. This lack of accuracy 

has been an obstacle to determining 

risks associated with failure modes, 

such as stress rupture and fatigue 

crack growth. Key phenomena in 

the understanding of COPV liner 

and composite response include 

overwrap stress-deformation states, 

liner mechanics, and liner/overwrap 

interface mechanics. Accurate 

quantification of the interference 

strain between the liner and overwrap 

is difficult to capture without 

measurement and model correlation. 

While closed-form solutions and FEA models with 

simple liner-overwrap interface assumptions may be 

calibrated to conservatively bound hoop strain response, 

they cannot accurately capture the complete multiaxial stress and deformation state to simultaneously 

correlate with all axial, circumferential, and volumetric 

deformation measurements, especially in the presence 

of an interface gap. The cited reference identifies ways 

in which measurements and model correlation can be 

performed. Global measurements taken from axial linear 

variable differential transducers (LVDTs), belly bands, and 

volumetric measurements, along with local measurements 

of axial and hoop strain from strain gages and laser 

profilometry measurements, were all demonstrated to 

be helpful in understanding the complex mechanical 

response of the COPV. COPVs are classified into 3 levels, 

and guidelines for measurements are suggested.

Best Practices for

Validation of COPV Models 

Three levels of measurements are recommended based 

on design burst safety factors and are intended to serve as 

guidelines for measurements on flight pressure vessels.

Level 1: Burst factor > 3.0

Determine composite and liner 

response based on analysis of the 

vessel per the as-built specifications 

and demonstrated burst pressure. 

Alternatively, determine composite 

and liner response based on closedform analysis of a measured fiber 

strain response (nominal or local) as 

a function of pressure to burst.

Level 2: 2.0 < Burst factor < 3.0

Determine composite and liner 

response based on fully verified FEA. 

Measurements needed as a function 

of applied internal pressure include:

1. Global measurements: Axial 

elongation by LVDT and internal 

volume growth.

2. Local measurements: Hoop 

and axial strain at equator and other carefully referenced 

positions by foil strain gages and/or full-field methods of 

optical metrology.

Level 3: Burst factor < 2.0

Determine composite and liner response based on fully 

verified finite element model. Measurements needed:

1. Global measurements: Axial elongation by LVDT and 

internal volume growth.

2. Local measurements: Hoop and axial strain at equator 

and other carefully referenced positions by foil strain gages 

and/or full-field methods of optical metrology.

3. Interior Laser Profilometry: Unwound liner, wound 

liners prior to overwrap cure, wound liner post-overwrap cure 

prior to autofrettage, and cured COPV post autofrettage.

References

Thesken, J.C., et. al., Composite Pressure Vessel Working 

Group (CPVWG) Task 4: A Theoretical and Experimental 

Investigation of Composite Overwrapped Pressure Vessel 

(COPV) Autofrettage, December 19, 2013. TM-2014-218260.

Global and local deformation measurements should be incorporated into the composite overwrapped 

pressure vessel (COPV) design and analysis process to allow correlation of these measurements with finite 

element analysis (FEA) models. This correlation improves understanding of liner, liner/overwrap interface, and 

composite deformation response in COPVs. The improved accuracy reduces error in subsequent analyses, 

such as fracture, fatigue, and stress rupture that are critical for COPV qualification. 

COPV Mechanical Model Validation 

LVDT Belly band cable

Strain

gauges

Cable extension 

transducer

Model correlation study test fixture.

NASA Engineering and Safety Center Technical Bulletin No. 14-03

National Aeronautics and Space Administration

Applicability

Development of experimental techniques and CFD predictive 

capabilities to determine proper placement and orientation 

of RCS jet thrusters on hypersonic entry vehicles to minimize 

adverse RCS JI.

Historical JI Prediction Issues

Historically, the prediction of hypersonic entry RCS effectiveness 

and associated JIs with surrounding flowfields has been 

a challenging CFD problem. For example, during the bank 

maneuvers of the first space shuttle orbiter reentry, the rolling 

moment that occurred when the forward yaw thrusters were 

fired was less than expected, resulting in greater RCS fuel usage 

than anticipated. The cause of this discrepancy was attributed 

to improper scaling of wind tunnel derived RCS interaction 

correlations to the flight condition.

1

 In a more recent example, 

CFD analyses of the RCS JI on the Mars Phoenix entry vehicle 

indicated the possibility of uncontrollable adverse JI, enough 

so that the project chose to not use the RCS during portions of 

the entry phase, increasing the landing footprint and the overall 

mission risk.

2

The Mars Science Laboratory (MSL) mission was plagued by 

similar issues in the early design phases. The entry vehicle 

aerodynamics was based on a combination of experimental 

results, CFD calculations, and comparisons with estimates of

flight aerodynamics from previous Mars missions. Estimates of 

the RCS effectiveness and RCS JI with the aftbody flow-field 

were originally developed based primarily on CFD calculations, 

indicating the potential for large, undesirable RCS JI. Recommendations were made to change the RCS jet locations and 

orientations in an attempt to reduce plume impingement on 

the spacecraft, jet-to-jet plume interactions, and to minimize 

undesirable interaction torques. Given the uncertainties 

associated with the wake flow predictive capabilities of current 

CFD codes, a wind tunnel test was designed and executed in 

the Langley Research Center 31-Inch Mach 10 Wind Tunnel 

to provide experimental data for the new MSL RCS thruster 

configuration design.

3

 This data served to provide validation 

results specific to MSL and, at the same time, the experimental 

test techniques developed would potentially be of benefit to other 

projects and programs employing blunt body entry aeroshell 

designs with aftbody RCS jet thrusters (e.g., Orion/Multi-Purpose 

Crew Vehicle or commercial crew vehicle designs). Additional 

CFD calculations were made on the new thruster configuration 

to assess effects of the aerodynamics and RCS interactions.

4

Results indicated generally good agreement between the 

experimental data and CFD predictions of the RCS JI. This, along 

with recommended conservative uncertainty values for RCS JI, 

provided an appropriate degree of confidence to the MSL Project 

on the adequacy of the new thruster configuration and overall 

robustness of the entry flight control system.

Conclusions and Guidance

Appropriate consideration must be given to RCS thruster locations 

and orientations to minimize impingements and interactions. 

Modern CFD tools should be used in conjunction with welldesigned experimental testing early in development to accurately 

predict the RCS JI and overall control effectiveness. 

References

1. Scallion, W.I., Compton, H.R., Suit, W.T., Powell, R.W., 

Blackstock, T.A., and Bates, B.L.: “Space Shuttle Third Flight 

(STS-3) Entry RCS Analysis,” AIAA Paper 83-0116

.

2. Dyakonov, A. A., Glass, C. E., Desai, P. N., and Van Norman, 

J. W.: “Analysis of Effectiveness of Phoenix Reaction Control 

System,” AIAA Paper 2008-7220

.

3. NASA/TM-2013-218023, NESC-RP-10-00613 Mars Science 

Laboratory (MSL) Reaction Control System (RCS) Jet Interactions 

(JI) Testing and Analysis, July 2013

4. Schoenenberger, M., Van Norman, J. V., Rhode, M., and Paulson, 

J.: “Characterization of Aerodynamic Interactions with the Mars 

Science Laboratory Reaction Control System Using Computation 

and Experiment,” AIAA Paper 2013-097

.

Aerodynamic Reaction Control System (RCS) Orientation

and Jet Interaction (JI) Model Validation 

Careful consideration should be given to placement and orientation of RCS jet thrusters on hypersonic entry 

vehicles in order to minimize adverse RCS JI. Modern state-of-the-art computational fluid dynamics (CFD) 

tools should be able to predict the RCS effectiveness and JI accurately when coupled with verification and 

validation studies, including the use of appropriately designed experimental wind tunnel testing. 

Comparison of MSL Aero/RCS interaction using 3 different CFD codes.

MSL model in LaRC 31-Inch 

Mach 10 Wind Tunnel.

Experimental flow image

of MSL RCS jets.

US3D Overflow FUN3D

NASA Engineering and Safety Center Technical Bulletin No. 14-02

34 35
Kevin P. Roscoe

In recognition of engineering excellence to the Atlantis 

Kennedy Space Center visitor center display and the 

Multi-Purpose Crew Vehicle Underway Recovery Tests 

Assessment.

James P. Smith

In recognition of engineering excellence to the MultiPurpose Crew Vehicle Avcoat Team leading to 

advancements in modeling and analysis of Avcoat 

material used in the Orion heatshield.

Eric T. Stoneking

In recognition of engineering excellence to the innovative 

dynamics and control contributions to the solution of 

the spacecraft hybrid attitude control problem for the

repurposed Kepler mission. 

Michael D. Vanek

In recognition of engineering excellence to the Raven 

Vision Navigation System impact on International Space 

Station visiting vehicles.

Vitali Volovoi

In recognition of engineering excellence to the NESC for 

reliability and modeling expertise including significant 

contributions to NESC Hubble Space Telescope tasks.

NESC Administrative Excellence Award

Kelly E. Barlow

In recognition of exceptional and dedicated support to the 

NESC Review Board and the NESC Technical Update.

NESC Group Achievement Award

Battery Thermal Runaway

Severity Reduction Testing Team

In recognition of outstanding support in the testing and 

development of design methods that will improve the 

safety of batteries for NASA human spaceflight missions.

Composite Overwrapped Pressure Vessel Strand 

Stress Rupture Test Rig Development Team

In recognition of creativity, flexibility, and expeditiousness 

in designing strand test rigs, protocols and infrastructure 

to meet and exceed performance, schedule, and cost 

requirements.

Exploration System Development Software

Interface Mapping Team

In recognition of outstanding system modeling efforts, 

training support, model analysis, review board support, 

and tool assessment for multiple NESC assessments.

Joint Polar Satellite System Micrometeoroid and 

Orbital Debris Assessment Team

In recognition of outstanding contributions to understanding the micrometeoroid and orbital debris environment 

models and risk for the Joint Polar Satellite System.

Layered Pressure Vessel Assessment Team

In recognition of outstanding contributions towards 

defining testing and analysis developments necessary to 

reduce the risk associated with continued operation of 

critical Agency layered pressure vessels.

NESC Leadership Award

Stan A. Bouslog

In recognition of outstanding leadership and technical 

support of the Multi-Purpose Crew Vehicle Avcoat Study.

Koushik Datta

In recognition of outstanding technical leadership of the 

Hubble Space Telescope Observatory System Reliability 

Review.

Michael E. Fowler

In recognition of outstanding leadership and technical 

support of the Multi-Purpose Crew Vehicle Avcoat Study.

Joseph H. Ruf

In recognition of outstanding leadership in identifying 

potentially inaccurate liquid engine nozzle acoustics 

and conducting scale model tests to confirm ignition 

acoustics environments for the Space Launch System 

booster design.

Kimberly A. Simpson

In recognition of outstanding leadership of the exploration 

systems development software interface mapping.

NESC Engineering Excellence Award

Scott P. Cryan

In recognition of engineering excellence to the Raven 

Vision Navigation System impact on International Space 

Station visiting vehicles.

Lorie R. Grimes-Ledesma

In recognition of engineering excellence for composite 

pressure vessel risk reduction efforts.

Justin S. Jones

In recognition of engineering excellence in support 

of the human space program by conducting critical 

nondestructive evaluation tests of failed extravehicular 

mobility unit components driving toward the return to 

extravehicular activity operations.

Anup B. Katake

In recognition of engineering excellence to the Raven 

Vision Navigation System impact on International Space 

Station visiting vehicles.

Chris J. Miller

In recognition of engineering excellence to the F/A-18 

Full-Scale Advanced Systems Testbed Space Launch 

System Launch Vehicle Adaptive Control Project.

Bruno F. Munoz

In recognition of engineering excellence to the human 

space program by conducting critical non-destructive 

evaluation tests of failed extravehicular mobility unit 

components driving toward the return to extravehicular 

activity operations.

James R. Reeder

In recognition of engineering excellence to the MultiPurpose Crew Vehicle Avcoat Team leading to 

advancements in testing and analysis of Avcoat material 

used in the Orion heatshield.

36

Members of the NESC team.

2014 award recipients left to right: Pat Forrester (NESC Chief Astronaut/presenter); Michael Fowler (JSC); Daniel Wentzel (WSTF); Stan Bouslog 

(JSC); Koushik Daata (ARC); Chris Miller (AFRC); Mike Kirsch (NESC Deputy Director/presenter); Kevin Bonanne (JPL); Joseph Ruf (MSFC); James 

Reeder (LaRC); Kimberly Simpson (JPL); Chris Iannello (NESC); William Prosser (NESC); Eric Stoneking (GSFC); Donald Kessler (Independent Consultant); Scott Cryan (JSC); Kelly Barlow (ManTech International Corp.); Anup Katake (JPL); Bruno Munoz (Ball Aerospace Corp.); Vitali Volovoi (Independent Contractor); Lorie Grimes-Ledesma (JPL); Michael Vanek (LaRC); Justin Jones (GSFC); Tim Wilson (NESC Director/presenter)

Not pictured: Kevin Roscoe (LaRC) and James Smith (JSC).

37

NESC Engineering Excellence Award

Continued

awards awards
Frank H. Bauer

NESC Discipline Expert for 

Guidance Navigation and 

Control (2003 - 04)

J. Larry Crawford

NESC Deputy Director for 

Safety (2003 - 04) 

Dr. Charles J. Camarda

NESC Deputy Director for 

Advanced Projects (2006 - 09) 

Kenneth D. Cameron

NESC Deputy Director for 

Safety (2005- 08) 

Steven F. Cash

NESC Chief Engineer at 

Marshall Space Flight

Center (2005) 

Derrick J. Cheston

NESC Chief Engineer at Glenn 

Research Center (2003 - 07) 

Mitchell L. Davis

NASA Technical Fellow for 

Avionics (2007 - 09) 

Dennis B. Dillman

NESC Chief Engineer at NASA 

Headquarters (2005 - 08) 

Freddie Douglas, III

NESC Chief Engineer at 

Stennis Space Center 

(2007 - 08) 

Patricia L. Dunnington

Manager, Management and

Technical Support Office 

(2006 - 08)

Walter C. Engelund

NESC Chief Engineer at 

Langley Research Center 

(2009 - 13)

Wayne R. Frazier

Senior SMA Integration 

Manager (2005 - 12)

Dr. Michael S. Freeman

NESC Chief Engineer at Ames 

Research Center (2003 - 04) 

T. Randy Galloway

NESC Chief Engineer at 

Stennis Space Center 

(2003 - 04)

Roberto Garcia

NASA Technical Fellow for 

Propulsion (2007- 13)

Dr. Edward R. Generazio

NESC Discipline Expert for 

Nondestructive Evaluation 

(2003 - 05) 

Dr. Richard J. Gilbrech

NESC Deputy Director 

(2003 - 05) 

Michael Hagopian

NESC Chief Engineer at 

Goddard Space Flight

Center (2003 - 07)

David A. Hamilton

NESC Chief Engineer at 

Johnson Space Center 

(2003 - 07) 

Dr. Charles E. Harris

NESC Principal Engineer

(2003 - 06) 

Dr. Steven A. Hawley

NESC Chief Astronaut 

(2003 - 04) 

Marc S. Hollander

Manager, Management and

Technical Support Office 

(2005 - 06)

George D. Hopson

NASA Technical Fellow for 

Propulsion (2003 - 07) 

Keith L. Hudkins

NASA Headquarters Office of 

the Chief Engineer

Representative (2003 - 07) 

Danny D. Johnston

NESC Chief Engineer at 

Marshall Space Flight

Center (2003 - 04) 

Michael W. Kehoe

NESC Chief Engineer at 

Dryden Flight Research 

Center (2003 - 05) 

Denney J. Keys

NASA Technical Fellow for 

Electrical Power (2009 - 12)

Robert A. Kichak

NESC Discipline Expert for 

Power and Avionics (2003 - 07) 

Dr. Dean A. Kontinos

NESC Chief Engineer at Ames 

Research Center (2006 - 07) 

Julie A. Kramer White

NESC Discipline Expert for

Mechanical Analysis (2003 - 06) 

Steven G. Labbe

NESC Discipline Expert for 

Flight Sciences (2003 - 06) 

Matthew R. Landano

NESC Chief Engineer at

Jet Propulsion Laboratory 

(2003 - 04) 

Dr. David S. Leckrone

NESC Chief Scientist 

(2003 - 06) 

Richard T. Manella

NESC Chief Engineer at Glenn 

Research Center (2009 - 10) 

John P. McManamen

NASA Technical Fellow for

Mechanical Systems 

(2003 - 07) 

Brian K. Muirhead

NESC Chief Engineer at

Jet Propulsion Laboratory 

(2005 - 07) 

Dr. Paul M. Munafo

NESC Deputy Director 

(2003 - 04) 

Stan C. Newberry

Manager, Management and 

Technical Support Office 

(2003 - 04) 

Dr. Tina L. Panontin

NESC Chief Engineer at Ames 

Research Center (2008 - 09)

Dr. Shamim A. Rahman

NESC Chief Engineer at 

Stennis Space Center 

(2005 - 06) 

Ralph R. Roe, Jr.

NESC Director (2003 - 14)

Jerry L. Ross

NESC Chief Astronaut 

(2004 - 06) 

Dr. Charles F. Schafer

NESC Chief Engineer at 

Marshall Space Flight

Center (2006 - 10)

Dawn M. Schaible

Manager, Systems 

Engineering Office (2003 - 14)

Steven S. Scott

NESC Chief Engineer at 

Goddard Space Flight

Center (2008 - 09) 

Bryan K. Smith

NESC Chief Engineer at Glenn 

Research Center (2008 - 10) 

Dr. James F. Stewart

NESC Chief Engineer at 

Armstrong Flight Research 

Center (2005 - 14)

Daniel J. Tenney

Manager, Management and

Technical Support Office 

(2009 - 13)

John E. Tinsley

NASA Headquarters Senior 

Safety and Mission Assurance 

Manager for NESC (2003 - 04) 

Timothy G. Trenkle

NESC Chief Engineer at 

Goddard Space Flight

Center (2009 - 13)

Clayton P. Turner

NESC Chief Engineer at 

Langley Research Center 

(2008 - 09)

38

Michael L. 

Aguilar

Software

Dr. Thomas 

M. Brown

Propulsion

Dr. Michael J. 

Dube

Mechanical

Systems

Cornelius J.

Dennehy

GNC

Clinton H. 

Cragg

Dr. Nancy J. 

Currie

Dr. Michael G. 

Gilbert

Michael D. 

Squire

Patrick A. Martin

NASA HQ Senior 

S&MA Integration 

Manager

Timmy R. 

Wilson

Director

Michael P. 

Blythe

Deputy Director

for Safety

Patrick G.

Forrester

Chief

Astronaut

Dr. Daniel

Winterhalter 

Chief Scientist

Michael T.

Kirsch

Deputy

Director

Steven J. 

Gentz

MSFC

Dawn C.

Emerson

GRC

R. Lloyd 

Keith

JPL

Nans

Kunz

ARC

Dr. W. Lance 

Richards

AFRC

Jill L. 

Prince

LaRC

Stephen A. 

Minute 

KSC

Joseph W.

Pellicciotti

GSFC

Dr. David M.

Schuster

Aerosciences

Henry A.

Rotter

Life Support/

Active Thermal 

Steven L. 

Rickman

Passive 

Thermal

T. Scott 

West

JSC

Michael D. 

Smiles

SSC

Dr. William H.

Prosser

NDE

Dr. Robert S. 

Piascik

Materials

Dr. Cynthia

H. Null

Human

Factors

Dr. Ivatury S. 

Raju

Structures

Oscar

Gonzalez

Avionics

Dr. Curtis E. 

Larsen

Loads & 

Dynamics

Daniel G. 

Murri

Flight

Mechanics

Dr. Christopher

J. Iannello

Electrical

Power

39

leadership team NESC alumni

NESC Principal Engineers NASA Technical Fellows

NESC Chief Engineers
Opposite: Carlie Zumwalt from LaRC inspects a supersonic parachute 

model in the LaRC Transonic Dynamics Tunnel as part of the NESC

Subscale Low Density Supersonic Parachute Wind Tunnel Test.

 1. Multi-Purpose Crew Vehicle (MPCV) Drogue Parachute High-Altitude Qualification ..................... NASA/TM-2013-218140/Volume I 

 2. Multi-Purpose Crew Vehicle (MPCV) Drogue Parachute High-Altitude Qualification - Appendices NASA/TM-2013-218140/Volume II 

 3. Cassini Plasma Spectrometer (CAPS) Short Circuit Anomaly ......................................................................... NASA/TM-2014-218047 

 4. Independent Assessment of External Pressure Field Predictions

Supporting Constellation Program Aeroacoustics ........................................................................................... NASA/TM-2014-218058 

 5. Asteroid Retrieval Mission (ARM) Solar Electric Propulsion (SEP) Other Trades Study (OTS) ........................ NASA/TM-2014-218159 

 6. Assessment of Combustion Instability in Black Brant (BB) Motors ................................................................. NASA/TM-2014-218160 

 7. Hubble Space Telescope (HST) Observatory System Reliability Review ........................................................ NASA/TM-2014-218161 

 8. NASA Engineering and Safety Center (NESC) Enhanced Melamine (ML) Foam Acoustic Test (NEMFAT) ...... NASA/TM-2014-218162 

 9. Spin Forming Aluminum Alloy Crew Module (CM) Metallic Forward 

Pressure Vessel Bulkhead (FPVBH) - Phase I .................................................................................................. NASA/TM-2014-218163 

10. International Space Station (ISS) Program Extravehicular Mobility Unit (EMU) Lithium Ion

(Li-Ion) Battery Assessment ............................................................................................................................. NASA/TM-2014-218164 

11. Orion Multi-Purpose Crew Vehicle (MPCV) Capsule Parachute Assembly System (CPAS)

Wake Deficit Wind Tunnel Testing .................................................................................................................... NASA/TM-2014-218171 

12. International Space Station (ISS) Orbital Replaceable Unit (ORU) Wet Storage Risk Assessment ................. NASA/TM-2014-218172

13. James Webb Space Telescope (JWST) Sunshade Venting Analysis ............................................................... NASA/TM-2014-218173 

14. SRTMV-N2 Plume Impingement Test Panel (PITP) Risk Mitigation

Experiment Technical Assessment Report ...................................................................................................... NASA/TM-2014-218255 

15. Composite Pressure Vessel Working Group (CPVWG) Task 4: A Theoretical and

Experimental Investigation of Composite Overwrapped Pressure Vessel (COPV) Autofrettage ..................... NASA/TM-2014-218260 

16. Use of Commercial-Off-The-Shelf (COTS) Electronic Components in Safety-Critical

Human-Rated (Commercial Crew) Space Avionics Systems .......................................................................... NASA/TM-2014-218261 

17. Orion Thermal Protection System (TPS) Margin Study, Phase 2 ..................................................................... NASA/TM-2014-218262 

18. Computer-Aided Design (CAD) Tools to Support the Human Factors Design Teams ..................................... NASA/TM-2014-218263 

19. Micrometeoroid and Orbital Debris (MMOD) Design and Analysis Improvements ........................... NASA/TM-2014-218268/Volume I 

20. Micrometeoroid and Orbital Debris (MMOD) Design and Analysis Improvements - Test Reports .. NASA/TM-2014-218268/Volume II 

21. Transonic Shock Reflections in Space Launch System (SLS) Wind Tunnel Testing ........................................ NASA/TM-2014-218269 

22. Review of Deep Space Atomic Clock (DSAC) Technology and Station Explorer for X-ray

Timing and Navigation Technology (SEXTANT) Demonstration Projects ......................................................... NASA/TM-2014-218270 

23. OSIRIS-REx Asteroid TAG Onboard OPNAV Capability .................................................................................. NASA/TM-2014-218277 

24. Review of Ground Systems Development and Operations (GSDO) Tools for Verifying

Command and Control Software ..................................................................................................................... NASA/TM-2014-218278

25. Benefits of Shell Buckling Knockdown Factor (SBKF) Project ........................................................................ NASA/TM-2014-218281 

26. Evaluation of Agency Non-Code Layered Pressure Vessels (LPVs) ................................................ NASA/TM-2014-218505/ Volume I 

27. Evaluation of Agency Non-Code Layered Pressure Vessels (LPVs) Appendices ........................... NASA/TM-2014-218505/ Volume II 

28. International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Plan Assessment Update ........... NASA/TM-2014-218512

29. Flight Testing of the Space Launch System (SLS) Adaptive Augmenting Control (AAC)

Algorithm on an F/A-18 .................................................................................................................................... NASA/TM-2014-218528 

30. A Comprehensive Analysis of the X-15 Flight 3-65 Accident .......................................................................... NASA/TM-2014-218538 

31. NASA Workshop on Hybrid (Mixed-Actuator) Spacecraft Attitude Control ..................................................... NASA/TM-2014-218539 

32. Maximum Expected Wall Heat Flux and Maximum Pressure after Sudden Loss of Vacuum Insulation

on the Stratospheric Observatory for Infrared Astronomy (SOFIA) Liquid Helium (LHe) Dewars .................... NASA/TM-2014-218540 

33. James Webb Space Telescope’s (JWST) Near-Infrared Spectrograph (NIRSpec) Micro

Shutter Subsystem (MSS) Alternate Materials and Coatings ........................................................... NASA/TM-2014-218541/Volume I 

34. James Webb Space Telescope’s (JWST) Near-Infrared Spectrograph (NIRSpec) 

Micro Shutter Subsystem (MSS) Alternate Materials and Coatings Appendices ............................ NASA/TM-2014-218541/Volume II 

35. International Space Station (ISS) External Thermal Control System (ETCS) Loop A Pump

Module (PM) Jettison Options Assessment ..................................................................................................... NASA/TM-2014-218542

36. Alternative Software Programming for Human Spaceflight ........................................................................................ TM-2014-218546

37. NASA Engineering and Safety Center (NESC) Independent Review and Support of the

International Space Station (ISS) Extravehicular Activity (EVA) Water Anomaly and EVA

Recovery Team (ERT) Failure Investigation ................................................................................................................. TM-2014-218547

 

40 41

2014 publications
8. Ku, J.; Robinson, F.: Testing of a Neon Loop Heat Pipe 

for Large Area Cryocooling. Spacecraft Thermal Control Workshop, March 25-27, 2014, El Segundo, Calif.

9. Orr, J. S.: A Critical Analysis of the X-15 3-65-96 

Accident − Part I: Aircraft Systems and Flight Control. 

Presented at Aerospace Control and Guidance

Systems Committee Meeting #114, Oct. 14, 2014,

Cleveland, Ohio.

10. Wilder, M. C.; Bogdanoff, D. W.; Saunders, D. A.: Heat 

Transfer Measurements on the Afterbody of Spheres 

in Hypersonic Free-Flight in Air and Carbon Dioxide. 

Submitted for consideration to AIAA Aviation 2015, 

June 22-26, 2015, Dallas, Texas (submission status 

expected in late Feb. 2015).

11. Yang, K.; Peabody H.: Preliminary Development of a 

TSS and SINDA/FLUINT to ESARAD/ESATAN Thermal 

Model Converter. Paper Number TFAWS2014-PT-03. 

Presented at the Thermal & Fluids Analysis Workshop, 

Aug. 5, 2014, Cleveland, Ohio.

12. Yen, J. C.; Akers, S. A.: A C-4 Blast Simulation Using 

a Hybrid Source-Propagation Approach by CTH and 

JUSTUS Codes. 60th JANNAF Joint Propulsion Meeting, April 29-May 3, 2013, Colorado Springs, Col.

Recent NESC Technical Discipline Team Member 

Scholarly Papers and Conference Proceedings

Continued

Recent NESC Technical Discipline Team Member

Scholarly Papers and Conference Proceedings

1. Allgood, D.: Predicting Blast Wave Propagation in 

Rocket Test Facilities Using a Simplified Source Model. 

60th JANNAF Joint Propulsion Meeting, April 29-May 3,

2013, Colorado Springs, Col.

 2. Brauckmann, G. J.; Streett, S. L.; Kleb, W. L.; Alter, S. 

J.; Murphy, K. J.; and Glass, C. E.: Computational and 

Experimental Unsteady Pressures for Alternate SLS 

Booster Nose Shapes. Submitted for AIAA SciTech, 

Jan. 5-9, 2015, Kissimmee, Fla.

 3. DellaCorte, C.; Moore III, L. E.: Launch Load Resistant Spacecraft Mechanism Bearings Made from NiTi 

Superelastic Intermetallic Materials. Proceedings of the 

42nd Aerospace Mechanisms Symposium, May 14-16, 

2014, NASA Goddard Space Flight Center, Md.

 4. Forsgren, R. C.: APPEL - Developing the Technical 

Workforce. Presented at NASA Virtual PM Challenge, 

Dec. 2, 2014, Hampton, Va.

 5. Jackson, E. B.; Shelton, R.; Jackson, A. A.; Castro, 

M. P; Noble, D. M.; Madden, M. M.; Litton, D. K.; 

Powell, R. W.; Queen, E. M.; Schidner, J. D.; Sellers, 

W. A.; Striepe, S. A.; Aguirre, J.; Zimmerman, C. J.; 

Lewis, E. K.; Reardon, S. E.; Vuong, N; Weinstein, M. 

J.: Development of Verification Check-Cases for Six 

Degree-of-Freedom Flight Vehicle Simulations. AIAA 

SciTech Guidance, Modeling and Simulation Technologies (MST) Conference, Jan. 2015, Kissimmee, Fla.

 6. Krantz, T.: Reducing Wear of Steel Rolling Against 

Ti6Al4V Operating in Vacuum. 42nd Aerospace Mechanism Symposium, May 14-16, 2014, Baltimore, Md.

 7. Ku, J.; Robinson, F.: Testing of a Neon Loop Heat Pipe 

for Large Area Cryocooling. Paper No. ICES 2014-35, 

44th International Conference on Environmental Systems, July 13-17, 2014, Tucson, Ariz.

 1. Ayari, L.; Kubitschek, M.; Ashton, G.; Johnston, 

S.; Debevec, D.; Newell, D.; Pellicciotti, J. W.: GMI 

Instrument Spin Balance Method, Optimization, 

Calibration, and Test. Presented at 42nd Aerospace 

Mechanisms Symposium, May 14-16, 2014,

Baltimore, Md.

 2. Dennehy, C. J.: Spacecraft Hybrid (Mixed-Actuator) 

Attitude Control Experiences on NASA Science 

Missions. Presented at ESA Conference on Guidance 

Navigation and Control, June 2-6, 2014, Porto, 

Portugal.

 3. Dennehy, C. J.; Brady, T.; Greenbaum, A.: Identifying 

Trends in Spacecraft GN&C Components: The 

Development and Application of an Open-Source 

GN&C Component Data base. Presented at 8th ESA 

Workshop on Avionics, Data, Control and Software 

Systems, Oct. 27-29, 2014, Noordwijk, Netherlands.

 4. Gilbert, M. G.: The Max Launch Abort System − 

Concept, Flight Test, and Evolution. Presented at 7th 

IAASS Conference, Oct. 20-22, 2014, Friedrichshafen, 

Germany.

 5. Hanson, C.; Miller, C.; VanZwieten, T.; Gilligan, E.; 

Orr, J.; Wall, J.: Launch Vehicle Manual Steering with 

Adaptive Augmenting Control: In-Flight Evaluations 

using a Piloted Aircraft. AIAA SciTech Guidance, 

Navigation, and Control Conference, Kissimmee,

Fla., 2015.

 6. Null, C. H.: Autonomy: The Role of HSI. Presented 

at Dept. of Defense Human Factors Engineering 

Technical Advisory Group Meeting 68, May 19-22, 

2014, Aberdeen, Md.

 7. Null, C. H.: DOD Human Factors - Verification. 

Presented at Department of Defense Human Factors 

Engineering Technical Advisory Group Meeting 68, 

May 19-22, 2014, Aberdeen, Md.

 8. Prosser, W. H.: Spacecraft NDE. Presented at IEEE 

Autotest 2014, Sept.15-18, 2014, St. Louis, Mo.

 9. Rickman, S. L.: A History of Spacecraft Thermal 

Analysis. Presented at Thermal and Fluids Analysis 

Workshop (TFAWS) 2014, Aug. 4-8, 2014, Cleveland, 

Ohio.

10. Rickman, S. L.: Introduction to On-Orbit Thermal 

Environments. Presented at Thermal and Fluids 

Analysis Workshop (TFAWS) 2014, Aug. 4-8, 2014, 

Cleveland, Ohio.

11. Schuster, D. M.: MAX Launch Abort System Flight Test. 

Presented at Seminar at the University of Cincinnati, 

Oct. 31, 2014, Cincinnati, Ohio.

12. Schuster, D. M.: NASA Computational Aerosciences. 

Presented at AVIATION 2014 (The Aviation and 

Aeronautics Forum and Exposition), June 16-20, 2014, 

Atlanta, Ga.

13. Shockey, D.; Piascik, R. S.; Jensen, B. J.; Hewes, L. S.; 

and Sutter, J. K.: Textile Damage in Astronaut Gloves. 

Journal of Failure Analysis and Prevention, Volume 13, 

No. 6, Dec. 2013, p. 748-756.

14. VanZwieten, T.; Gilligan, E.; Wall, J.; Orr, J.; Miller, 

C.; Hanson, C: Adaptive Augmenting Control Flight 

Characterization Experiment on an F/A-18. AAS 

Guidance, Navigation, and Control Conference, 

Breckenridge, Col., AAS 14-052, 2014.

15. Wall, J.; VanZwieten, T.; Gilligan, E.; Miller, C.; Hanson 

C.; Orr, J.: In-Flight Suppression of an Unstable F/A18 Structural Mode Using the Space Launch System 

Adaptive Augmenting Control System. AIAA SciTech 

Guidance, Navigation, and Control Conference, 

Kissimmee, Fla., 2015.

Recent NESC Scholarly Papers and Conference Proceedings

42

Kevin A. Lett of Jacobs Technology at WSTF instruments a Max Launch Abort System frangible joint for testing. Frangible 

joints can be used as the structural interconnection between stages of a launch vehicle and spacecraft.

43

2014 publications
The end of the successful Exploration Flight Test-1. 

The NESC performed numerous assessments for the 

Orion Multi-Purpose Crew Vehicle Program.

U.S. Pacific Fleet
National Aeronautics and Space Administration

Langley Research Center

Hampton, VA 23681

NP-2014-11-577-LaRC

www.nasa.gov