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O
TA12 Materials, Structures,
Mechanical Systems, and Manufacturing
INTRODUCTION
The draft roadmap for technology area (TA) 12 Materials, Structures, Mechanical Systems, and Manufactur-
ing, is organized into five level 2 technology areas:1
• 12.1 Materials
• 12.2 Structures
• 12.3 Mechanical Systems
• 12.4 Manufacturing
• 12.5 Cross-Cutting
The TA12 portfolio is extremely broad and differs from most other TAs in that it consists of enabling core
disciplines and encompasses fundamental new capabilities that directly impact the increasingly stringent demands
of NASA science and exploration missions. These missions depend highly on advancements such as lighter and
stronger materials and structures, with increased reliability and with reduced manufacturing and operating costs.
Identified technologies are truly interdisciplinary and support virtually all of the other TAs.
In TA12, NASA identified two critical areas: human radiation protection and reliability technologies. Long-
term human exploration will require new radiation protection technology, i.e., lightweight radiation-shielding mate-
rials, multifunctional structural design and innovative manufacturing. Crosscutting technologies will be required
to ensure extremely reliable vehicles and systems for safe travel to destinations millions of miles from Earth.
Before prioritizing the level 3 technologies included in TA12, the panel considered whether to rename, delete,
or move technologies in the technology area breakdown structure (TABS). No changes were recommended for
TA12. The TABS for TA12 is shown in Table O.1, and the complete, revised TABS for all 14 TAs is shown in
Appendix B.
1 The draft space technology roadmaps are available at http://www.nasa.gov/offices/oct/strategic_integration/technology_roadmap.html.
294
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TABLE O.1 Technology Area Breakdown Structure for TA12, Materials, Structures, Mechanical Systems, and
Manufacturing
NASA Draft Roadmap (Revision 10) Steering Committee-Recommended Changes
The structure of this roadmap remains unchanged.
TA12 Materials, Structures, Mechanical Systems,
and Manufacturing
12.1. Materials
12.1.1. Lightweight Structure
12.1.2. Computational Design
12.1.3. Flexible Material Systems
12.1.4. Environment
12.1.5. Special Materials
12.2. Structures
12.2.1. Lightweight Concepts
12.2.2. Design and Certification Methods
12.2.3. Reliability and Sustainment
12.2.4. Test Tools and Methods
12.2.5. Innovative, Multifunctional Concepts
12.3. Mechanical Systems
12.3.1. Deployables, Docking, and Interfaces
12.3.2. Mechanism Life Extension Systems
12.3.3. Electro-mechanical, Mechanical, and
Micromechanisms
12.3.4. Design and Analysis Tools and Methods
12.3.5. Reliability/Life Assessment/Health
Monitoring
12.3.6. Certification Methods
12.4. Manufacturing
12.4.1. Manufacturing Processes
12.4.2. Intelligent Integrated Manufacturing and
Cyber Physical Systems
12.4.3. Electronics and Optics Manufacturing Process
12.4.4. Sustainable Manufacturing
12.5. Crosscutting
12.5.1. Nondestructive Evaluation and Sensors
12.5.2. Model-Based Certification and Sustainment
Methods
12.5.3. Loads and Environments
TOP TECHNICAL CHALLENGES
The panel identified six top technical challenges for TA12. These are described briefly below in priority order.
While not inconsistent with those identified in the NASA roadmap document itself, they differ in that there was
no attempt to explicitly include challenges in each of the level 2 areas represented; that is: materials, structures,
mechanical systems, manufacturing, and crosscutting.
1. Multifunctional Structures. Conceive and develop multifunctional structures, including shielding, to enable
new mission capabilities such as long-duration human spaceflight, and to reduce mass.
Structures carry load and maintain shape. To the extent that a structure can simultaneously perform additional
functions, especially those that would normally require add-on systems, mission capability can be increased with
decreased mass. Integral shielding to reduce radiation exposure and micrometeoroid and orbital debris (MMOD)
risk for human spaceflight missions would be game-changing, and the ISS would be useful to verify such concepts.
Other advanced multifunctional structures concepts would enable structures, including joints, to provide thermal
protection and control, electrical signal and power transmission, electrical energy and fuel storage, self-sensing
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296 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
and healing, and active shape control. Improved cryogenic boil-off protection, for instance, would considerably
reduce the mass required for a Mars mission. Such multifunctional materials and structures will require new design
analysis tools and might exhibit new failure modes; these should be understood for use in systems design and
space systems operations.
2. Reduced Mass. Reduce mass of launch vehicle, spacecraft, and propulsion structures to increase payload mass
fraction, improve mission performance, and reduce cost.
Lightweight materials and structures are required to enhance mission performance and enable new mission
opportunities. Advanced composites and revolutionary structural concepts would substantially reduce structural
weight in launch vehicles, cryo-tanks, propulsion systems, and spacecraft, increasing the payload mass fraction.
More energetic propellants would reduce fuel mass in solid motors, and higher-temperature and lower-erosion
materials would reduce the weight of engine nozzles. Reduced mass of inflatable habitats and space structures,
deployable space systems, and large-scale structures would enable new exploration and science missions.
3. Computational Modeling. Advance new validated computational design, analysis, and simulation methods for
materials and structural design, certification, and reliability.
First-principles physics models offer the game-changing potential to guide tailored computational materials
design. Multi-scale models are needed to encompass composite materials, interfaces, failure, multi-component and
deployable structures, and integrated control systems; multi-physics models are needed to address manufacturing
processes, operation in extreme environments, and active materials. Conservatism is embedded in established
design methodology in several ways, including statistics-based material allowables and traditional factors of safety.
Uncertainty management and quantification, if supported by an experimental foundation, offers the potential to
reduce weight as well as certification and life-cycle costs by rationalizing sometimes excessive conservatism.
Physics-based and computation-based errors can be quantified and compared to required accuracy and confidence
levels. A validated computational modeling methodology could provide the basis for certification by analysis,
with experimental evidence, as available, used to verify and improve confidence in the suitability of a design.
Computational models will be needed to design-in improved reliability, as well as to interpret measurements made
by health-monitoring systems. Structures may need to be designed differently to accommodate health monitoring,
including unobtrusive sensors and sensor integration, and to enable materials and structures health assessment and
sustainability for long-duration missions.
4. Large-Aperture Systems. Develop reliable mechanisms and structures for large-aperture systems. These must
be stowed compactly for launch, yet achieve high-precision final shapes.
Numerous NASA missions employ mechanical systems and structures that must deploy reliably in extreme
environments, often to achieve a desired shape with high precision. Such systems include instrument arms, anten -
nas, optical surfaces, solar sails, and some re-entry thermal protection systems. These can be deployed, assembled,
or manufactured in space, and may involve flexible materials. Modularity and scalability are desirable features of
such concepts, and may require development of autonomous adaptive control systems and technology to address
critical functional elements and materials. Concerns include sliding joints and bearings, friction and tribology,
coatings and lubrication, as well as their performance and durability over extended periods in storage and extreme
operational environments. Performance of large precise space systems cannot be directly verified in the 1- g ground
environment, so the ISS would be useful for verification of such concepts.
5. Structural Health Monitoring. Enable structural health monitoring and sustainability for long-duration mis -
sions, including integration of unobtrusive sensors, and responsive on-board systems.
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APPENDIX O
Mission assurance would be enhanced by an integrated structural health monitoring system that could detect
and assess the criticality of in-service damage or fault, then define an amelioration process or trigger a repair in
self-healing structures. Such a system requires light, reliable, rugged, unobtrusive, and multifunctional sensors
that can be integrated into the structure along with power and data transmission capability. Software to combine
disparate data, to diagnose and predict structural health, and to enable the necessary repairs is also a significant
challenge. An autonomous integrated on-board systems capability would be game-changing for long-duration,
remote missions.
6. Manufacturing. Enable cost-effective manufacturing for reliable high-performance structures and mechanisms
made in low-unit production, including in-space manufacturing.
Advanced NASA space missions need affordable structures, electronics systems, and optical payloads. Afford -
able high-performance structures require advances in manufacturing technology. Such advances include automation
using reusable flexible tooling; database- and model-based simulation to ensure selection of the lowest-cost yet
reliable and scalable approach; non-autoclave processes for polymer matrix composites to minimize infrastructure
investment; in-space manufacture and assembly of large structures such as fuel depots; and means for cost-effective
manufacture of lightweight precision optical systems for large structures. In-space manufacturing offers the poten -
tial for game-changing weight savings and new mission opportunities; as an example, NASA and DARPA recently
pursued the possibility of manufacturing large optical systems in space. The ISS could be used to demonstrate
lightweight in-space structures manufacturing capability.
QFD MATRIX AND NUMERICAL RESULTS FOR TA12
Figure O.1 shows the panel’s consensus ratings of the 23 level 3 technologies for the TA12 roadmap.
Clearly, benefit is the major discriminator among these technologies, while technical risk and reasonableness
is the second most important discriminator. Alignment is a less significant discriminator. Most TA12 technologies
have the potential to impact multiple NASA missions in multiple areas because every mission would benefit from
reduced structural mass, and most would benefit from improved structural reliability and reduced cost.
Figure O.2 shows the consensus rankings of the level 3 technologies. As shown in the figure, 12.2.5 Innova -
tive Multifunctional Concepts received the highest QFD score. A couple of break points in the consensus scores
facilitate sorting into relative high, medium, and low-priority categories. The two top medium-ranked technologies
were promoted into the high-priority category because of their close relationship to other high-priority technologies.
12.3.5 Reliability/Life Assessment/Health Monitoring is important in its own right, and it closely supports 12.3.1
Deployables, Docking and Interfaces. 12.4.2 Intelligent Integrated Manufacturing and Cyber Physical Systems 2
supports a number of other high-priority technologies and NASA missions.
CHALLENGES VERSUS TECHNOLOGIES
Figure O.3 shows the relationship between the 23 individual level 3 TA12 technologies and the top technical
challenges.
Note that the lowest-priority technologies as determined by the QFD rankings tend not to be strongly connected
to the top technical challenges. (These are identified by an “L” in the left-most column, and are linked to the top
challenges mainly by open circles.) All of the high-priority technologies and many of the medium-priority ones
have a strong connection to at least one of the top technical challenges. This shows a good level of consistency in
the evaluations by the panel.
2 A cyber-physical system (CPS) features tight coordination between computational and physical elements. A CPS typically involves a
network of interacting elements, and is closely tied to concepts of robotics and sensor networks.
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298 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
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Alignment Risk/Difficulty
Technology Name Benefit
236 H
12.1.1. (Materials) Lightweight Structure 3 9 9 9 9 -1 -3
164 M
12.1.2. (Materials) Computational Design 3 9 9 9 1 1 -3
168 M
12.1.3. Flexible Material Systems 3 9 3 3 3 1 -1
156 M
12.1.4. (Materials) Environment 3 9 3 1 3 1 -3
98 L
12.1.5. Special Materials 1 9 1 1 3 -1 -1
244 H
12.2.1. (Structures) Lightweight Concepts 3 9 9 9 9 1 -3
236 H
12.2.2. (Structures) Design and Certification Methods 3 9 9 9 9 -1 -3
106 L
12.2.3. (Structures) Reliability and Sustainment 1 9 3 3 3 -1 -1
94 L
12.2.4. (Structures) Test Tools and Methods 1 9 3 1 3 -3 -1
346 H
12.2.5. (Structures) Innovative, Multifunctional Concepts 9 9 9 9 3 1 -3
216 H
12.3.1. Deployables, D ki
12 3 1 D l bl Docking, and I t f
d Interfaces 3 9 3 1 9 -1
1 -1
1
90 L
12.3.2. Mechanism Life Extension Systems 1 9 1 1 3 -3 -1
90 L
12.3.3. Electro-mechanical, Mechanical and Micromechanisms 1 9 1 1 3 -3 -1
228 H
12.3.4. (Mechanisms) Design and Analysis Tools and Methods 3 9 9 9 9 -3 -3
184 H*
12.3.5. (Mechanisms) Reliability / Life Assessment / Health Monitoring 3 9 9 9 3 -1 -1
176 M
12.3.6. (Mechanisms) Certification Methods 3 9 9 9 3 -1 -3
176 M
12.4.1. Manufacturing Processes 3 9 9 9 3 -3 -1
184 H*
12.4.2. Intelligent Integrated Manufacturing and Cyber Physical Systems 3 9 9 9 3 -1 -1
98 L
12.4.3. Electronics and Optics Manufacturing Process 1 9 3 3 3 -3 -1
78 L
12.4.4. Sustainable Manufacturing 1 9 3 3 1 -3 -1
236 H
12.5.1. Nondestructive Evaluation and Sensors 3 9 9 9 9 -1 -3
164 M
12.5.2. Model-Based Certification and Sustainment Methods 3 9 9 3 3 -1 -3
98 L
12.5.3. Loads and Environments
12.5.3. Loads and Environments 1 9 3 3 3 -1 -3
FIGURE O.1 Quality function deployment (QFD) summary matrix for TA12 Materials, Structures, Mechanical Systems,
and Manufacturing. The justification for the high-priority designation of all high-priority technologies appears in the section
“High-Priority Level 3 Technologies.” H = High Priority; H* = High Priority, QFD score override; M = Medium Priority; L
= Low Priority.
0 50 100 150 200 250 300 350 400
12.2.5. (Structures) Innovative, Multifunctional Concepts
12.2.1. (Structures) Lightweight Concepts
High Priority
12.1.1. (Materials) Lightweight Structure
12.2.2. (Structures) Design and Certification Methods
12.5.1. Nondestructive Evaluation and Sensors
12.3.4. (Mechanisms) Design and Analysis Tools and Methods
12.3.1. Deployables, Docking, and Interfaces
12.3.5. (Mechanisms) Reliability / Life Assessment / Health Monitoring
12.4.2. Intelligent Integrated Manufacturing and Cyber Physical Systems
Medium Priority
12.3.6. (Mechanisms) Certification Methods
12.4.1. Manufacturing Processes
12.1.3. Flexible Material Systems
12.1.2. (Materials) Computational Design
12.5.2. Model‐Based Certification and Sustainment Methods
12.1.4. (Materials) Environment
12.2.3. (Structures) Reliability and Sustainment
12.1.5. Special Materials
Low Priority
12.4.3. Electronics and Optics Manufacturing Process
12.5.3. Loads and Environments
12.2.4. (Structures) Test Tools and Methods
12.3.2. Mechanism Life Extension Systems High Priority (QFD Score Override)
12.3.3. Electro‐mechanical, Mechanical and Micromechanisms
12.4.4. Sustainable Manufacturing
FIGURE O.2 Quality function deployment rankings for TA12 Materials, Structures, Mechanical Systems, and Manufacturing.
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Top Technology Challenges
5. Structural Health
1. Multifunctional
6. Manufacturing:
Monitoring: Enable
4. Large-Aperture
Structures: Conceive
Enable cost-effective
structural health
Systems: Develop
3. Computational
2. Reduced Mass:
and develop
manufacturing for
monitoring and
reliable mechanisms
Modeling: Advance new
Reduce mass of launch
multifunctional
reliable high-
sustainability for long-
and structures for large-
validated computational
vehicle, spacecraft, and
structures, including
performance structures
duration missions,
aperture systems.
design, analysis and
propulsion structures to
shielding, to enable new
and mechanisms made
including integration of
These must be stowed
simulation methods for
increase payload mass
mission capabilities
in low-unit production,
unobtrusive sensors,
compactly for launch,
materials and structural
fraction, improve
such as long-duration
including in-space
and responsive on-
yet achieve high-
design, certification, and
mission performance,
human space flight, and
manufacturing.
board systems.
precision final shapes.
reliability.
and reduce cost.
to reduce mass.
Priority TA 12 Technologies, Listed by Priority
H 12.2.5. (Structures) Innovative, Multifunctional Concepts ● ○
H 12.2.1. (Structures) Lightweight Concepts ○ ● ●
H 12.1.1. (Materials) Lightweight Structure ○ ●
H 12.2.2. (Structures) Design and Certification Methods ○ ○ ● ○ ○
H 12.5.1. Nondestructive Evaluation and Sensors ● ○
H 12.3.4. (Mechanisms) Design and Analysis Tools and Methods ● ●
H 12.3.1. Deployables, Docking, and Interfaces ●
H 12.3.5. (Mechanisms) Reliability / Life Assessment / Health Monitoring ○ ● ●
12.4.2. Intelligent Integrated Manufacturing and Cyber Physical Systems
H ○ ○ ●
M 12.3.6. (Mechanisms) Certification Methods ○ ●
M 12.4.1. Manufacturing Processes ○ ●
M 12.1.3. Flexible Material Systems ● ○ ○
M 12.1.2. (Materials) Computational Design ○ ○ ●
M 12.5.2. Model-Based Certification and Sustainment Methods ● ●
12.1.4. (Materials) Environment
M ● ○ ○
L 12.2.3. (Structures) Reliability and Sustainment ○ ○ ●
L 12.1.5. Special Materials ○ ○
L 12.4.3. Electronics and Optics Manufacturing Process ○
L 12.5.3. Loads and Environments ○ ●
L 12.2.4. (Structures) Test Tools and Methods ○ ○
L 12.3.2. Mechanism Life Extension Systems ○ ○
L 12.3.3. Electro-mechanical, Mechanical and Micromechanisms ○
L 12.4.4. Sustainable Manufacturing ○
Strong Linkage: Investments by NASA in this technology would likely have a
● major impact in addressing this challenge.
Moderate Linkage: Investments by NASA in this technology would likely have a
○ moderate impact in addressing this challenge.
Weak/No Linkage: Investments by NASA in this technology would likely have
[blank]
little or no impact in addressing the challenge.
FIGURE O.3 Level of support that the technologies provide to the top technical challenges for TA12 Materials, Structures, Mechanical Systems, and Manufacturing.
299
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300 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
Furthermore, many of the TA12 roadmap technologies are connected to each other in support of a common
top technical challenge or a crosscutting roadmap technology. For instance, many of the roadmap technologies
support challenges related to reliability, health monitoring, and sustainability.
HIGH-PRIORITY LEVEL 3 TECHNOLOGIES
Panel 5 identified nine high-priority technologies in TA12. The justification for ranking each of these tech -
nologies as a high priority is discussed below.
Technology 12.2.5, Innovative, Multifunctional Concepts (Structures)
Structures that perform functions in addition to carrying load and maintaining shape can increase mission
capability while decreasing mass and volume, potentially benefitting all future space missions. Multifunctional
structural concepts involve increasing levels of system integration and provide a foundation for increased autonomy.
Habitat structures with integral shielding would reduce radiation exposure and MMOD risk for long-duration
human spaceflight missions; these might involve flexible materials and inflatable structures. Other innovative
multifunctional concepts would enable load-bearing structures to provide thermal isolation, control and protection
in cryo-tanks, habitats, sensor supports and TPS, and address joints as well as primary structure. These concepts
would enable on-orbit fuel storage depots and benefit human exploration and science missions by reducing the mass
and complexity of thermal control systems. (For instance, improved cryogenic boil-off protection would reduce
mass for a Mars mission by 50 percent; Braun, 2011). Sensory and controlled structures would benefit from the
ability to conduct electrical signals and power, enabling health monitoring and adaptation. Other multifunctional
structures might store energy and autonomously repair damage.
Multifunctional structures technology is considered to be at TRL 2 for many level 4 technology items, TRL 3
in several cases, such as integrated MMOD protection, and up to TRL 5 for integrated windows and active control
of structural response. The highest-priority technologies are at TRL 2-3.
The human spaceflight applications of multifunctional structures technology are unique to NASA and dictate
that NASA lead associated technology development. Some multifunctional structures concepts, such as those
involving thermal-structural and electrical-structural functionality, are likely to find broader applications in multiple
areas and multiple missions, and beyond the aerospace field, including electronics and aircraft. NASA would benefit
from partnerships in the development of these technology concepts. One example of a potential cooperative effort
might be the commercial development and demonstration of thermally conductive electronics support structures.
Some elements of multifunctional structures concepts would benefit from access to the ISS. Specifically,
demonstration of habitat structures with integral radiation and MMOD shielding, including long-term exposure
to the space environment would increase the TRL of such concepts. While beneficial for other multifunctional
technology concepts, access to the ISS would not be required.
This technology is game-changing because multifunctional habitat structures with integral shielding could
reduce radiation exposure and MMOD risk for human spaceflight, bringing risk levels into acceptable ranges with
reduced structural mass and launch vehicle volume. Other multifunctional structures technologies are likely to
impact multiple areas and multiple missions and find uses beyond the aerospace field. The development risk is
moderate-to-high, perhaps exceeding that of past efforts to develop comparable technology.
Technology 12.2.1, Lightweight Concepts (Structures)
Lightweight structural concepts could significantly enhance future exploration and science missions and enable
new missions. Improved performance of reduced mass launch vehicle systems with increased payload mass fraction
could provide benefits for all future space missions. Lightweight cryo-tank concepts could improve launch vehicle
performance and potentially enable on-orbit fuel storage depots (crosscutting with TA14). Small-scale inflatable
space systems concepts have been demonstrated and commercial scale-up for inflatable crewed systems are planned
for later this decade. These concepts and lightweight inflatable ground habitats could enable future exploration
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APPENDIX O
missions. Lightweight concepts for deployable solar sails, precision space structures, and inflatable, deployable heat
shields could provide opportunities for new missions or significantly benefit planned science missions. Advanced
composite materials play an important role in developing lightweight structural concepts. Integration of advanced
materials and structures technology provide the maximum benefit in development and optimization of lightweight
concepts.
Lightweight (structural) concepts are considered to be at TRL 2-3 to 5. Some inflatable space systems have
been demonstrated at TRL 6. Examples of lightweight structures concepts at TRL 2-3 include cold hibernating
elastic memory self-deployable structures and partially flexible composites with shape memory wire.
Lightweight structural concepts developed by NASA and the aerospace industry have found extensive appli -
cations in transportation, commercial aircraft and military systems. Some space applications of lightweight con -
cepts, such as aluminum-lithium cryo-tank structures, solid rocket motor cases, and payload structures, have been
demonstrated; however, there are significant new opportunities for adoption of lightweight concepts for future
space missions. NASA can partner with other government agencies and/or industry where possible to develop and
demonstrate lightweight concepts that will support future NASA missions. An example of a potential cooperative
effort is the commercial development and demonstration of an inflatable space habitat that would further NASA’s
exploration goals.
Some elements of lightweight concepts would benefit from access to the ISS. Specifically, demonstration of
in-space manufacturing of lightweight structures, deployment of an inflatable module, and long-term exposure of
materials used in these concepts would increase the TRL of lightweight concept technologies. While beneficial,
access to the ISS is not required.
Lightweight concepts technology could significantly benefit all exploration and science missions and is aligned
with NASA’s goals and objectives. The level of risk for lightweight concepts technology ranges from moderate
to high depending on the specific technology and application. Many of the lightweight concepts beyond TRL 2-3
are mission dependent, and the timing and effort required to advance from lower TRLs to TRL 6 will depend on
the specific application.
Weight reductions from lightweight concepts technology could significantly enhance planned exploration and
science missions and have the potential to enable new missions. Lightweight structural concepts for habitats, safe
havens, and ground-based infrastructure, particularly those technologies that satisfy multifunctional requirements,
could enable new human exploration missions to the Moon or Mars. Lightweight deployable structures can enable
future science missions with requirements for large-scale structures, precision deployment, and shielding.
Technology 12.1.1, Lightweight Structure (Materials)
Advanced composite, metallic, and ceramic materials, as well as cost-effective processing and manufacturing
methods, are required to develop lightweight structures for future space systems. Further advances are needed
if increased benefits from lightweight structures are to be attained. The application of non-autoclave-cured large
composite structures to launch vehicles would likely reduce structural weight by more than 30 percent compared to
metallic structures. Advanced material systems could enable multifunctional structural designs to reduce radiation
levels, improve MMOD protection, and enhance thermal management. Incorporation of nanotechnology-engineered
materials in lightweight structures offers the potential for game-changing weight saving and performance improve -
ments (crosscutting with TA10). Materials technology for lightweight structures is relevant to all of NASA’s planned
and future missions.
Lightweight materials are considered to be generally at TRL 2-3, and higher in select areas. Moderate effort
is required to reach TRL 6, comparable to that of previous efforts.
Lightweight structural materials developed by NASA and other government agencies, academia, and the
aerospace industry have found extensive applications in transportation, commercial aircraft, and military systems.
Continued NASA leadership in materials development for space applications could result in new materials systems
with significant benefits in weight reduction and cost savings. NASA will likely have opportunities to pursue these
materials in partnership with other federal agencies and industry.
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302 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
Access to the ISS is not required for development of lightweight materials; however, the ISS could serve as
a test bed for evaluation of the exposure of such materials to the space environment.
This technology has the potential to significantly reduce the mass of virtually all launch vehicles and
payloads—creating opportunities for new missions, improved performance, and reduced cost. The level of
risk for materials development and lightweight structures ranges from moderate to high, with non-autoclave-
cured composites as a moderate risk, and development and incorporation of nanotechnology materials in high-
performance lightweight structures a modestly higher risk.
Technology 12.2.2, Design and Certification Methods (Structures)
Current structural certification approaches rely on a conservative combination of statistics-based material
qualification and experience-based load factors and factors of safety, followed by design development and quali -
fication testing. Verification testing and mission history indicates that structures tend to be over-designed and
thus heavier than necessary. A model-based “virtual digital certification” methodology could be developed to
design and certify space structures more cost-effectively. Advanced physics-based models that predict structural
response, failure modes, and reliability using deterministic and probabilistic approaches are a key requirement for
such a methodology. This methodology and associated models should be verified and validated with test data at
all necessary levels of scale and complexity to ensure confidence in their application. A design and certification
methodology based on validated high-fidelity analytical models promises payoffs in weight savings by reducing
excess conservatism in the current methodology and in cost reduction by eliminating the large-scale structural
tests that are currently required.
Methods for advanced design and certification are considered to be generally at TRL 3. This is determined
by the availability of validated models for virtual digital certification.
NASA has been a leader in developing this technology. Investments from the Air Force Research Labs in
similar technologies have contributed significantly and are expected to continue. Several national labs have signifi -
cant programs in uncertainty management and quantification. The technology to be developed is not only critical
in terms of weight reduction and affordability improvements to NASA’s space missions but also to DOD space
structures. NASA can partner with other federal agencies that also have interest in this technology, such as DOD
and DOE, to leverage existing expertise.
Access to the ISS is not required for this technology development. However, ISS design development and
qualification test data may be useful in validating the new models and methodologies resulting from this technol -
ogy development.
This technology provides another path to lighter and more affordable space structures while assuring adequate
reliability. A verified and validated model-based design and certification methodology offers payoffs in lightweight
structural designs and affordable certification without extensive testing, while ensuring long-term reliability of
space structures. Physics-based models will be required to simulate structural response in a virtual digital fleet
leader (VDFL) that would include a digital representation of a vehicle and a real time system to assess vehicle
health and identify action necessary to address vehicle performance. Overall, the benefits of this technology rank
below those of multifunctional and lightweight structures and materials. Since multiple NASA missions would
benefit from improved structural design and analysis capability, the technology alignment was among the highest
in this technology area. This high ranking carried over to non-NASA structures as well, since improvements in
lightweight structures design, probabilistic design methods, and simulation will also benefit DOD, DOE, and other
advanced structural applications. The risk and level of difficulty associated with this technology is high, since
significant effort from NASA, industry, academia, and other government agencies will be required to advance the
current state of the art. Further, although the objectives have been identified, several challenges need to be over-
come, particularly in model development and virtual testing, to reach TRL 6.
This technology is applicable to all NASA space vehicles including uncrewed, robotic and human-rated
vehicles for use in science missions, and human exploration over extended periods of time.
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Technology 12.5.1, Nondestructive Evaluation and Sensors (Crosscutting)
Non-destructive evaluation (NDE) has evolved from its early uses for quality control, product acceptance, and
periodic inspection to include continuous health monitoring and autonomous inspection. New NDE and sensor
technology, including in situ embedded sensor arrays to assess vehicle and space systems health, integrated analysis
to predict vehicle and on-board systems operational capability, and autonomous NDE and sensor operations, will
be required for long-duration space missions. Early detection, localization, and mitigation of critical conditions will
enhance mission safety and reliability. NASA has proposed an integrated NDE and sensor technology capability
in a VDFL that would include a digital representation of a vehicle with real time assessment of vehicle structural
health to predict performance and identify operational actions necessary to address vehicle performance. VDFL is
an initial step in an overall systems approach to monitor, identify, assess, and respond to on-orbit conditions that
impact mission success.
Non-destructive evaluation and sensor technology is considered to be at TRL 2-3 for many level 4 technology
items. However, some sensor technology is at a higher level and will require integration into vehicle systems to
achieve an overall TRL 6.
Nondestructive evaluation and sensor development by NASA and other government agencies, industry, and
academia has led to improved product quality and reduced failures of space structures. Partnership opportunities
exist with academia, industry, and other organizations in the development of new NDE and sensor technology
Access to the ISS is not generally required for continued development of nondestructive evaluation and sensor
technology.
NDE and sensor technology can result in a major increase in reliability of missions. NDE and sensor technology
has numerous crosscutting applications and the potential for significant enhancement of safety and mission assur-
ance of future long-duration space missions. NASA missions would benefit from an integrated NDE approach to
monitor, identify, assess, and respond to on-orbit conditions that impact human exploration and science missions.
NASA has proposed a VDFL as an eventual technology development. This concept could be expanded to address
not only structural integrity of space vehicles, but to include overall vehicle system performance and operation.
The VDFL concept has the potential to be game-changing, though not in a 20-year horizon.
NDE and sensor technologies are likely to impact multiple areas and multiple missions, especially as mission
durations continue to increase. Assessing and maintaining vehicle integrity with minimal human intervention will
be essential for long-duration missions involving complex vehicles and for finding uses beyond the aerospace
field. The development risk is moderate-to-high, and consistent with that of past efforts to develop comparable
technology. Judgment suggests a clear utility for this technology but no specifically identified users, though the
opportunity may exist for partnerships with other agencies.
Technology 12.3.4, Design and Analysis Tools and Methods (Mechanical Systems)
High-fidelity kinematics and dynamics design and analysis tools and methods are essential for modeling,
designing, and certifying advanced space structures and mechanical systems including turbomachinery, landing
systems and deployment mechanisms. This technology includes the tools and interfaces required to increase data
flow rates between various systems to enable real time use of mechanical system data. A mechanism interrelation/
correlation analysis methodology would enable creation of a single model of spacecraft mechanical systems and
would reduce the stack-up of margins across disciplines, e.g., aero-loads, vehicle dynamics, and structural response.
Such models could be integrated into a health-management system for diagnosis, prognosis, and performance
assessment and in a VDFL system.
This technology includes control design techniques for achieving deployment, stiffness control, shape control,
and disturbance rejection. This involves perhaps iterative technology development, since the models that yield
the best control results are not the same models used for other purposes (stress analysis, for instance). The most
appropriate model should be used for control design, and such models may not be totally physics-based.
Methods for advanced design and analysis are considered to be generally at TRL 2. This is determined by the
availability of interrelation/correlation analysis systems.
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NASA has been actively developing design and analysis tools and methods for kinematics and rotor dynamics
analyses and precursor flight high-data-rate technologies for space vehicle mechanisms. The Air Force Research
Laboratory has also invested in deployable mechanisms modeling and testing. The technology is required for both
NASA and Air Force space vehicles. NASA could lead or partner with other federal agencies that also have interest
in this technology.
Access to the ISS is not required for this technology development. However, deployable systems tested on-
orbit can provide valuable data for development of analysis tools.
This technology can enable a dramatic increase in the reliability of mechanical systems, such as those required
for separation, release, and deployment. Improved predictive modeling of spacecraft mechanical systems will
reduce overall stack-up of margins across disciplines leading to reduced weight and better performance of con -
cepts with minimal ground testing. The overall benefit of this technology is in the same class as 12.2.2 Design and
Certification Methods for structures. Since multiple NASA missions would benefit from improved mechanisms
design and analysis capability, the technology alignment was among the highest in this technology area. The risk
and level of difficulty associated with this technology were rated as high since significant effort from NASA,
industry, academia, and other government agencies would be required to advance the state of the art.
This technology is applicable to all NASA space vehicles including uncrewed, robotic and human-rated
vehicles for use in science missions, and human exploration over extended periods of time.
Technology 12.3.1, Deployables, Docking, and Interfaces (Mechanical Systems)
Many future science missions involving imaging and scientific data collection will benefit from the com -
bination of a large aperture and precision geometry. Achieving such structures within the constraints of antici -
pated launch vehicles will most likely involve deployment, possibly including flexible materials, although other
approaches including assembly or in-space manufacturing can be considered. Docking and the associated inter -
faces provide another approach to building up larger platforms from smaller ones, and these are encountered in
human spaceflight missions, along with habitats deployed from flexible materials. These mechanical systems and
structures must deploy reliably in extreme environments and achieve a desired shape with high precision; some
systems may require the use of a control system to maintain a precise shape under operational disturbances. Such
systems include antennas, optical elements, and solar sails. Modularity and scalability are desirable features of
such concepts.
Deployables, docking, and interfaces technology beyond the current applications for antennas, solar panels,
sun shields, and landing systems for science missions and docking systems on the ISS is considered to be at TRL
2-6 for many level 4 technology items, and nominally at TRL 4. Advanced deployables and docking systems have
been developed to TRL 6, but typically for smaller systems. The highest-priority technologies are at TRL 3-4.
Large precise aperture systems are critical to some NASA science missions as well as to some DOD surveil -
lance missions, enabling advanced mission performance. This suggests that NASA lead associated technology
development, finding partners when feasible.
Some aspects of deployable structures and docking concepts would benefit from access to the ISS. If the
systems are relatively large and flexible, their performance cannot be directly verified in the 1- g and 1-atmosphere
ground environment. In these cases, the ISS could be used to verify such concepts or to validate design and cer-
tification models.
This technology will assure the reliable deployment and expected high performance of large precision struc -
tures. Without demonstrations associated with this technology, there would continue to be considerable uncertainty
and risk involved in fielding such systems. These systems will provide major increases in performance for NASA
science missions. Many aspects of precision deployable structures and mechanisms technology are likely to find
broader applications in multiple areas and multiple missions, and to a large subset of the aerospace field that requires
precise structural geometry. The development risk is moderate-to-high, similar to that of past efforts to develop
comparable technology. Judgment suggests a clear utility and clear users, with some possibility of partnerships
with other agencies. Space missions have not infrequently failed as the result of failure of a separation, release or
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deployment system. The pursuit of improvements in the reliability of such systems is a critical technology devel -
opment area.
Technology 12.3.5, Reliability/Life Assessment/Health Monitoring (Mechanical Systems)
In recent experience, the reliability of mechanical systems, including deployment, separation and release, and
motorized systems, has been a more significant contributor to the failure of space missions than the reliability of
structures designed to meet current certification standards. Important technical concerns include sliding joints and
bearings, friction and tribology, coatings, and lubrication, as well as their performance and durability over extended
periods in storage and extreme operational environments. An integrated sensor system would provide a basis for
determining the current state of a mechanical system, as well as prediction of future behavior. To be most effective
in assuring mission reliability, the ability to take corrective action must also be designed into the system.
Reliability, life assessment, and health monitoring technology is considered to be at TRL 2-3 for many level
4 technology items, TRL 4 for environmental durability testing, and TRL 1 for general life extension prediction
and the VDFL concept. Reliability can be advanced significantly for specific classes of mechanical systems at a
time.
Mission success requires highly reliable spacecraft mechanical systems, especially for long-duration missions.
Some elements of mechanical systems reliability would benefit from access to the ISS. For instance, long-term
exposure of materials and operation of devices would increase the TRL. While beneficial, access to the ISS is not
required.
This technology could enable a dramatic increase in the reliability of mechanical systems and structures, espe -
cially for long-duration space missions. The intrinsic risk associated with such missions could be reduced through
the development of health monitoring systems. This technology area is closely linked with the area of deployables,
docking, and interfaces, which itself was ranked high in the QFD evaluation. Significant improvement in the reli -
ability of mechanical systems would have a major benefit on assurance of space mission success. Many aspects of
reliable mechanisms technology are likely to find applications in multiple areas and multiple missions, to the broad
aerospace field, and in some non-aerospace fields. The development risk is moderate-to-high, perhaps exceeding
that of past efforts to develop comparable technology. There is a good possibility for outside partnerships.
Technology 12.4.2, Intelligent Integrated Manufacturing
and Cyber Physical Systems (Manufacturing)
As a rule, the fielding of high-performance materials, structures, and mechanisms for space applications
requires specialized manufacturing capability. Through advances in technology, largely IT-based, more general but
flexible manufacturing methods can be adapted to produce specialized components and systems. A database and
data-mining capability would be useful to support a terrestrial and interplanetary design, manufacturing, and opera -
tions supply chain. High-fidelity manufacturing process models could be used to simulate various manufacturing
scenarios to enable rapid evaluation of process alternatives. An intelligent product definition model could be used
to simulate the full behavior of components through all stages of their life cycle. Hardware and software technolo -
gies will need to be coordinated to develop the next generation of robotics and automation for space structures.
This will require the development of cyber-physical systems that enable adaptable and autonomous manufacturing
for long-duration crewed spaceflights, including direct digital manufacturing (DDM). In-space manufacturing has
the potential to be game-changing by reducing the structural mass that must be delivered to orbit or to the surface
of other worlds.
Intelligent integrated manufacturing technology is considered to be at TRL 4, as determined by the availability
of validated product definition, and manufacturing process models. In-space manufacturing is at a considerably
lower TRL, perhaps 1-2.
There are existing industrial capabilities in production process modeling, factory automation and simulation,
and product life-cycle modeling. Investments from the Air Force Research Labs in similar technologies have con -
tributed significantly and are expected to continue because of the potential impacts on affordability. Manufacturing
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is an area in which NASA can benefit from monitoring developments in hardware, software, and supply chain
management. There is potential to form government, university, and industry consortia to pursue these ends.
Access to the ISS is not required for this technology development. However, the ISS could be a useful platform
to test in-space manufacturing processes.
This technology would enable physical components to be manufactured in space, on long-duration human
missions if necessary. For some exploration missions, this could reduce the mass that must be carried into space.
Furthermore, this technology promises improved affordability of one-off structures made from high-performance
materials. Multiple NASA missions, especially science missions with constrained budgets, would benefit from
cradle-to-grave product life-cycle and manufacturing simulation to select affordable designs. For instance, non-
autoclave processes would substantially reduce the infrastructure investment needed to manufacture small runs of
large polymer matrix composite structures. Additionally, NASA and DARPA recently conducted a study focused
on developing larger (>100 m), lighter space-based optical systems using in-space manufacturing. Small-scale
(mm) manufacturing concepts were demonstrated, but significant effort would be required to scale up to mean -
ingful optical systems. This technology is perhaps at TRL 2, and has potential for ISS demonstration. Therefore,
the technology alignment for NASA applications was among the highest in this technology area. This high rank -
ing, however, did not carry over to non-NASA applications, where amortization over multiple units changes the
manufacturing approach required to ensure affordability.
The risk and level of difficulty associated with this technology were rated as high since significant effort from
NASA, industry, academia, and other government agencies will be required to advance the current state of the art.
This technology is applicable to all NASA space vehicles including uncrewed, robotic and human-rated
vehicles for use in science missions, and human exploration over extended periods of time.
MEDIUM- AND LOW-PRIORITY TECHNOLOGIES
TA12 contains 23 level 3 technologies, of which 14 were determined to be of medium or low priority. Six
technologies were rated medium priority, not including the two that were originally rated medium priority but
were promoted to the high-priority category, and eight were rated low priority.
The ranked QFD results, shown in Figure O.1, provide some insight into the reasons that these technologies
did not receive high-priority ratings.
For these six medium-priority technologies, the technical risk was considered to be either too low or the
required effort was considered unreasonable. A second factor for the lower half of these technologies was reduced
alignment with non-NASA aerospace technology and national goals. In the medium-priority technologies there are
significant efforts underway in the aerospace industry and other agencies related to manufacturing processes, flex -
ible structures, certification methods for mechanical systems, model-based certification and sustainment methods,
materials computational design, and environmental materials characterization.
Most of the level 4 technology items associated with 12.3.6 Certification Methods are at a low TRL. NASA
should be able to partner with others in the development of many of the level 4 items in 12.4.1 Manufacturing
Processes, and the panel has included 12.4.1(d) In-Space Assembly, Fabrication, and Repair with the high-priority
technology 12.4.2 Intelligent Integrated Manufacturing and Cyber Physical Systems. 12.1.3 Flexible Materials
Systems supports 12.2.5 Innovative Multifunctional Concepts, as well as 12.3.1 Deployables, Docking, and Inter-
faces. The benefits of research in 12.1.2 Computational Design of Materials are unlikely to be realized within
the timeframe addressed by this study. 12.5.2 Model-Based Certification and Sustainment was also regarded as a
valuable goal, but with benefits unlikely to be realized within the study timeframe.
The likely benefit of pursuing the eight low-priority technologies, broadly defined, was considered to be smaller
than that of pursuing the high- and medium-priority technologies. Furthermore, the technical risk associated with
these technologies was considered to be either too low, or the required effort was considered unreasonable. Finally,
these technologies generally exhibited reduced alignment with non-NASA aerospace technology and national goals.
While important in selected aerospace applications, technologies such as special materials, electronics and optics
manufacturing processes, electromechanical and micromechanical systems and sustainable manufacturing were
identified as areas where industry, other agencies, and academia could partner with NASA in selected technology
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development related to future NASA missions. Technology areas including loads and environment, test tools and
methods, and mechanical life extension methods were rated similarly as technology efforts best conducted through
industry and academia partnerships.
The monitoring aspects of 12.5.3 Loads and Environments might be considered to be included with 12.5.1
Nondestructive Evaluation and Sensors. 12.5.1 Special Materials is a kind of “grab-bag” of unrelated technologies
that did not generally fit well with this roadmap. The panel suggests that the associated level 4 technology items
be supported as needed by likely users. NASA could partner with others in the development of some of the level
4 items of 12.4.3 Electronics and Optics Manufacturing Process, while the technology related to large ultra-light
precision optical structures fits well with other high-priority technology areas. 12.3.3 Electro-mechanical, Mechani-
cal, and Micromechanisms includes a variety of perhaps unrelated level 4 technology items.
DEVELOPMENT AND SCHEDULE CHANGES FOR THE
TECHNOLOGIES COVERED BY THE ROADMAP
Perhaps as a result of the need to address such a broad range of technologies in a summary document, the TA12
roadmap devotes little space to discussion of the assumed mission model, or to the inter-dependence of technology
development. To some degree, it can be read as a catalog of technology items as much as it can be read as a plan.
While such information is included in the Figure 2 foldout in the draft roadmap, detailed interpretation is left to
the reader. This makes it challenging to suggest specific modifications to the schedule.
OTHER GENERAL COMMENTS ON THE ROADMAP
The TA12 roadmap addresses neither improved understanding of the intense vibroacoustic environment of
launch nor novel approaches that could reduce structural dynamic response. These extreme loads frequently drive
the structural design of spacecraft. This is most closely associated with the following level 3 technologies: Loads
and Environments 12.5.3. (Crosscutting); and Design and Certification Methods 12.2.2. (Structures). There is also
a crosscutting aspect with active control of vibroacoustic environments and response (TA04).
PUBLIC WORKSHOP SUMMARY
The workshop for the TA12 Materials, Structures, Mechanical Systems, and Manufacturing technology area
was conducted by the Materials Panel on March 10, 2011, at the Keck Center of the National Academies, Wash -
ington, D.C. The discussion was led by panel chair Mool Gupta. He started the day by giving a general overview
of the roadmaps and the NRC’s task to evaluate them. He also provided some direction for what topics the invited
speakers should cover in their presentations. After the introduction, the day started with an overview of the NASA
roadmap by the NASA authors, followed by several sessions addressing the key areas of each roadmap. For each
of these sessions, experts from industry, academia, and/or government provided a 35 minute presentation/discus -
sion of their comments on the NASA roadmap. At the end of the day, there was approximately 1 hour for open
discussion by the workshop attendees, followed by a concluding discussion by the panel chair summarizing the
key points observed during the day’s discussion.
Roadmap Overview by NASA
The NASA team presented an overview of the TA12 roadmap. They noted that in developing the roadmap,
they focused on innovating and game changing areas instead of incremental improvements. The team also indicated
that they looked at both push areas (e.g., physics-based methods, materials, intelligent manufacturing, sustainment,
reliability) as well as pull areas (e.g., affordability, multifunctionality, lightweight, environmentally friendly).
Overall, the team identified 23 different technologies in the roadmap, and noted that many of these are cut across
different disciplines outside the TA12 roadmap. The team also noted that during the roadmap development, they
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had substantial interaction with the other NASA individuals developing the other TA roadmaps. Finally, the team
highlighted that they believed the TA12 roadmap was aligned with the NASA strategic objectives.
One topic that the NASA team indicated was a key focus of their roadmap was the VDFL. This technology
includes high-fidelity modeling and simulation, design and certification methods, situational awareness, and life
prediction and sustainment. According to the team, the VDFL is needed for future NASA endeavors such as deep
space travel, where it is difficult to do resupply or provide safe havens in case of emergencies. Essentially, they
indicated that the VDFL is a long-term technology aimed at lowering costs and improving reliability for future
NASA missions.
The NASA team also spent some time discussing the top technical challenges that they developed in the TA12
roadmap. In terms of the overall top challenges, the team noted that radiation protection for humans and reli -
ability rose to the top of the list. They also identified top challenges for specific areas, including: materials (e.g.,
new tailored materials, computational materials technologies), structures (e.g., robust lightweight/multifunctional
structures, VDFL), mechanical systems (e.g., higher reliability and predictable performance, precision deployable
mechanisms for large space structures), and manufacturing (e.g., advanced manufacturing processes, sustainable
manufacturing).
After the NASA presentation, a discussion period followed in which several panel members asked the team
questions. In responding to a question how the NASA team views the role of nanomaterials in structures, the team
responded that they identified products out of the TA10 roadmap that they could use. They noted that materials,
manufacturing, and structures work at a larger scale, and there is a need to figure out how to use/implement nano -
materials at this larger level. The team noted that areas such as using nanoclays as a toughener and permeability
barrier are likely nearer term. Other areas, such as negative CTE materials and platelet materials (to decrease
permeability and increase life) have already seen some use in consumer products or flight systems. One workshop
attendee also concurred with this viewpoint that applications are becoming nearer term, and that in the next 5 to
10 years much more exploitation should be possible.
The concept of the VDFL also generated some discussion. One of the panel members indicated that he viewed
the VDFL as a kind of systems engineering technology, rather than a materials/structures technology. He also
commented that he felt the VDFL did not go far enough, as it should also include propulsion, guidance/navigation
and control (GN&C), on-board sensors, and other features to both monitor and transmit health on all subsystems.
Another panel member noted that the NASA team had mentioned certifying models would be part of VDFL, and
asked whether this is the overall approach to validation and verification (V&V). The NASA team responded that
models for qualification and certification already exist, and that the VDFL is really about making a transition to
certifying the models, rather than certifying the program/mission. The team also noted that each vehicle using
VDFL will be a test case for improving the models over time.
Session 1: Materials
Tia Benson Tolle (Air Force Research Laboratory) presented her comments on the NASA roadmap. She
indicated she was encouraged to see the acknowledgement in the roadmap of the need for a long-term investment
strategy, as well as the push/pull tension built into the roadmap portfolio. She noted that multiple studies have
concluded that building in such tension is a proven approach for maximizing innovation and improving product
development. Benson Tolle also emphasized that computational design/methods are key to accelerated maturation
of complex engineered materials, and they will be relied on more in the future. She noted that while there have
been good individual efforts focused on improving computational methods, there is still a need to have a broader
and more integrated approach. Benson Tolle also discussed several other materials areas, including hybrid materials,
morphing materials, emerging energy harvesting technologies, leveraging TPS investments, and digital manufactur-
ing processes. In terms of the top technical challenges, she commented that for the exploitation of nanotailoring,
the role of the interface (and its effect on matrix material) is only generally understood, and could use more focus
to advance this. Some high-priority technology areas that Benson Tolle emphasized include multifunctional materi -
als, and integrated computational materials science and engineering (ICMSE). Finally, she noted that nanotailored
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composites and three-dimensional fiber architectures are near the tipping point where additional investments can
help mature these areas.
After Benson Tolle’s presentation, workshop participants asked her whether AFRL had formal programs for
interacting with NASA research programs. Benson Tolle responded that for her area (i.e., materials), she was not
aware of any particular forums for interaction, but that other areas (e.g., engine development) have formal pro -
cesses. She did note, however, that there certainly appears to be room for further collaboration with NASA (i.e.,
in taking advanced materials to the point where they can be exploited for air and space applications). Later in the
discussion, another participant asked Benson Tolle about AFRL’s experience in the tradeoffs of multifunctional
materials. Benson Tolle answered that first, optimization at the system level must be done early on. Second, she
noted that as researchers engineer materials further, the opportunity to change the property tradeoff space may
open up.
Byron Pipes (Purdue University) followed with a presentation of his views of the NASA roadmap. He noted
that while the industry has used composites for more than 30 years, there is still an inability to accurately predict
failure modes, and that this results in overdesigning composite structures. Relative to computational materials,
Pipes indicated that there are both the “design aided by experiments” and “certification aided by experiments”
aspects to consider. He commented that multiscale modeling provides a way to certify materials in ways that
do not require experiments. Pipes then suggested that NASA’s goal should be to think about simulation driven
materials and structures certification, as well as about simulation driven materials and structures design. He also
noted that while NASA serves both aero and space with very different goals (i.e., pervasiveness in aero versus
unique solutions in space), human safety is a central issue to both. Pipes indicated that some areas to emphasize
might include materials (e.g., computational design materials), structures (e.g., design and certification), cross-
cutting model-based certification, and manufacturing (e.g., manufacturing processes). He also noted that micro
design models are an area to emphasize with high priority. Pipes then asked the question that, for virtual digital
certification, how do you get the FAA and other groups to think more about this? He highlighted this as an area
that impacts all missions. Finally, Pipes concluded noting smart materials and devices is another area with a low
TRL that might provide benefits to NASA (e.g., health monitoring).
After Pipes’ presentation, workshop participants noted that it is important to incorporate early in the process
the mechanism for integrating sensors into the structure, and commented that NASA has projects looking into
this (e.g., MEMS). Pipes also suggested that there is more to be done in terms of data acquisition analysis and
that it is more than just building the sensor into the structure. On another topic, a participant commented that the
Boeing 787 symbolizes the state of the art in certification, and asked Pipes what he felt the next steps were. Pipes
responded that there are many significant capabilities coming out of the labs that can be taken advantage of. He
also indicated that it would be desirable to take some of the uncertainty and empiricism out of the models, as it is
becoming increasingly unaffordable to test every piece of structure in every vehicle in the future. Pipes concluded
that the science is there, but only recently have has computational power advanced to allow full use of thishe
indicated that he believes there will be many more improvements in the next 10 years.
Session 2: Structures
Les Lee (Air Force Office of Scientific Research; AFOSR) started with a brief overview of AFOSR and its
research portfolio. He noted that one of the key areas of focus is in multifunctional design and materials. He notes
that in some cases the performance for these may be less than a unifunctional part, but that this is acceptable as
long as the overall system improves—system metrics are needed to quantify this. In terms of the NASA roadmap,
Lee indicated that the roadmap appeared to be well laid out and contained a good balance between push and pull
technologies. He did suggest that the roadmap could use more emphasis on the integration between materials
and structures for multifunctional design, as well as providing more coverage of “weakest links” (e.g., joints,
discontinuities). On this latter point in particular, a workshop attendee concurred that 90 percent of the issues
she deals with are in the interface. Lee also commented that the roadmap coverage on predictive capabilities and
VDFL integration appeared to be optimistic; while he indicated he thought this would be useful, he did not think
it should be used as an excuse to skip verification testing. Also, Lee noted that although the roadmap coverage
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of reliability analysis was good, there also needed to be some focus on game changing areas such as autonomic
systems. Finally, Lee indicated that self-healing technology is important (e.g., repeated healing), and is critical for
deep space missions.
Lisa Hill (Northrop Grumman) noted up front in her presentation that cost and affordability are key con -
siderations for technology investments, yet this only shows up in the NASA roadmap at a high level. While she
indicated that the roadmap does a good job in laying out where we could go, it would also benefit from more quan -
tification of why. Hill also commented that the push/pull discussion was done well, as was the concept of linking
technologies to a long-term goal (e.g., VDFL). On the other hand, she identified potential gaps (e.g., digital direct
manufacturing), as well as areas that could use additional clarification (e.g., the various structures and materials
technologies in the roadmap with similar names, the significant connectivity with the TA10 roadmap). Hill also
questioned why solar sails were listed as a mission in the roadmap in 2020, as they are already flying at small
scales. In terms of VDFL, she noted that currently minimal data is obtained from structures and mechanisms, and
that unless forced into the system design, contractors typically will not include these. Hill also commented that
the VDFL tools sound useful, but if they are available and used in the design, then the VDFL would not be needed
later. Some of the top technical challenges that Hill mentioned include mass producible (e.g., hundreds to tens
of thousands annually), modularity, scalability, and obtaining useful performance data on structures (e.g., joints).
She did identify some technology gaps in the roadmap, however, including minimal discussion of the production
aspects of modular structures, materials and deployments for large optical systems, and concepts for dealing with
launch loads in different ways (e.g., friction in joints for damping).
Session 3: Mechanical Systems
Rakesh Kapania (Virginia Polytechnic Institute and State University) started his presentation by commenting
that materials are very important, but so is how they are placed (i.e., direction, geometry). According to Kapania,
there are several technology areas that he sees as key to the roadmap: deployables, dockings, and interfaces (e.g.,
extensibility, correlation between scaled and full-size models), mechanism life extension systems (e.g., under-
standing the response of structures to non-stationary random excitations), electro-mechanical systems, design and
analysis tools and methods (e.g., connecting analysis with health monitoring, modeling for multifunctional struc -
tures, importance of numerical ill-conditioning), reliability/life assessment/health monitoring (e.g., miniaturization,
reliability-based structural optimization), and certification methods (e.g., computational-based certification, need
for reduced-order modeling, reliability of computers and software). Kapania identified several top technical chal -
lenges, including: miniaturization to reduce weight, lack of information on loading environment, effects of radia -
tion on material properties, and analysis and design of multidisciplinary systems (e.g., information management,
reliable software). In terms of gaps in the roadmap, Kapania noted that energy requirements, energy harvesting,
fiber optics based sensors, and distributed sensing could all use more attention. He also commented that there are
several high-priority areas for NASA specifically, including: miniaturization and optimization, reliable software for
multi-system analysis, and understanding failure modes of multifunctional materials. Kapania also suggested that
some aspects of fabrication (e.g., from computer file to three-dimensional object, with sensing, actuation, comput -
ing, damage detection, and self-repairing all built in) as well as reliable software able to perform multi-system
analysis accurately without conditioning problems are game changing areas. When asked after his presentation on
what areas NASA should lead, Kapania responded that one area is in characterizing the space environment—i.e.,
what it is, what the loads are. He noted that once the requirements are understood, progressing to a solution is
straightforward. Kapania also commented that structural health monitoring (which he considers to be near a “tip -
ping point” of significant benefit with additional investment) is something desired by most industries, including
those outside aerospace (e.g., the automotive industry).
Session 4: Manufacturing and Crosscutting Areas
Ming Leu (Missouri University of Science and Technology) started his presentation by identifying technologies
in the manufacturing and crosscutting areas contained in the NASA roadmap. For in-space assembly, fabrication,
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APPENDIX O
and repair, he suggested that NASA could potentially take the lead in this. Leu also added two new areas to the
Manufacturing Process area: multi-scale modeling and simulation (as large increases in computer power make this
important), and nanomanufacturing (where NASA should look to leverage existing National Science Foundation
investments). Leu provided detailed commentary on several technology areas, including: Laser Assisted Material
Processing (which is an advanced type of three-dimensional printing applicable to in-space manufacturing and
repair), intelligent integrated manufacturing and cyber physical systems, sustainable manufacturing (including
consideration of environment, economy, and energy—E3—aspects), Nondestructive Evaluation (NDE), and loads
and environments. On NDE in particular, Leu noted that the roadmap appears to focus primarily on ultrasound
techniques; he suggested that other methods (e.g., eddy current, microwave, millimeter wave) should also be
looked at, and that sensor fusion is another aspect deserving attention. Relative to the top technical challenges in
the NASA roadmap, Leu commented that making accurate predictions based on multi-scale modeling will take
a long time, and that trying to make complex three-dimensional parts with high precision is difficult. He also
commented that there appeared to be some gaps in the roadmap, including: multi-scale modeling and simulation,
nanomanufacturing, and lifecycle product and process design (or E3 technologies). Leu indicated several areas
that he views as high-priority for NASA, including autonomous fabrication, repair, and assembly at point of use,
advanced robotics, functionally gradients composites capable of surviving very-high-temperature environments.
In terms of technologies close to a tipping point, Leu noted that composites manufacturing (and polymer matrix
composites in particular) could benefit substantially from additional investment. Finally, Leu commented after his
presentation that in his view, it is important for NASA to get involved in these areas as the industry is typically
not willing to invest.
Glenn Light (Southwest Research Institute) followed Leu with a presentation on his perspectives on the NASA
roadmap. Light noted that the roadmap stated its goals well in terms of how NDE technologies can feed into the
safety/reliability of long-duration space missions and the assessment/maintenance of vehicle integrity with mini -
mal human intervention. He also commented that the roadmap provided a good discussion on prognostics (i.e.,
the ability to detect defects, assess the situation, and provide a prognosis of remaining life or usage), and that
this is an area deserving of attention. On the other hand, Light also highlighted some areas that he felt the NASA
roadmap did not cover as well, including: types of defects and damage that might be anticipated, practical aspects
and effective integration of sensors and sensor life, sensing and monitoring the fields/environment around the
structure, technology to route repairing materials through the structure, and wireless power transfer to sensors. In
terms of top technical challenges in NDE and sensor systems, Light indicated that these include sensor integration
with minimal detrimental effects, sensitivity to early damage, increasing sensor life, sensors and micro-circuitry
embedded in the structure, environmental protection for structures (e.g., coatings), and the ability to monitor how
coatings are wearing. Light also discussed several areas he felt are high-priority for NASA, including: development
of sensors in practical form factors, wireless power transfer to embedded sensors (e.g., local energy harvesting),
on-call repair technologies and self-healing metals and composites, and integration of embedded sensors as part of
the structural design. As for alignment with NASA, he indicated that many of these areas align well with NASA’s
expertise, capabilities, and facilities. Light did suggest that there is a need to set clearly defined national goals
for the space program, and minimize the requirement for cost sharing and need to have dual-use technologies
(which many federal contracts do). Light also highlighted several technologies that he considers game-changing,
including capillary repair materials, practically embedded sensor arrays that positivity impact structural strength,
and sending power to all sensors wirelessly. He additionally noted that remote sensing of the environment around
the structure is near a tipping point and may benefit from further investment. Regarding embedded sensors, Light
indicated that this requires a new concept for teaching structural design. Finally, in responding to a question from
a workshop participant on the use of fiber optics embedded for sensing purposes, Light noted that this is good for
some things (e.g., stress analysis), but the main issue to date has been the detrimental impact to the structure.
Public Comment and Discussion Session
The following are views expressed during the public comment and discussion session by either presenters,
members of the panel, or others in attendance.
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312 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
• Individual observations on technology development. One workshop attendee provided a relatively detailed
set of observations based on his being involved in the technology development efforts at a U.S. government
agency. He noted that materials are very different for space systems, as issues with radiation resistance
and aggressive environments need to be accounted for. He also commented that space systems are typi -
cally low-rate production programs. This attendee then suggested that in computational modeling, most
methods do not account for manufacturing variability, and that there have been some spectacular failures
when this was used as the basis for validating the system. He emphasized that there is no substitute for
testing; while there are many physics-based models out there, there is an issue with not knowing everything
that might impact a system. An example he provided of this is for impurities in lithium ion batteries, and
the fact that these components still need to be tested for 10 years to understand their 10 year lifetime.
Finally this attendee noted the need to think politically to be successful in receiving technology fund -
ing; he suggested that looking for dual-use technologies at low manufacturing readiness, and looking at
productizing these, might be a way to do this.
• Collaboration with other agencies. During the discussions in the day, several presenters and attendees
highlighted the need for NASA to look at how to take advantage of other agencies’ investments in technol -
ogy development. One workshop attendee indicated that there is a lack of a formal interchange process
for technology development among these different groups, and suggested that the NASA Office of the
Chief Technologist look to stand up a process like this. This attendee also commented that NASA should
look at the National Research Laboratories, AFRL, and other groups, and perform a gap analysis to find
out which areas might be most applicable to and worthy of NASA investment.
• Radiation protection. One of the panel members noted that NASA had identified radiation protection as
one of its top technical challenges in the roadmap. This spurred many comments, including some from
the NASA team suggesting that they are looking at materials like metal organic foam in tanks to help
as shielding for habitat modules. Another workshop attendee noted that for protecting electronics, there
are two approaches: radiation-hardened electronics, or radiation protection for non-radiation-hardened
electronics. He commented that if NASA develops better ways to shield spacecraft from radiation, it could
have a large benefit for uncrewed spacecraft systems as well. Building on this comment, another attendee
noted that taking more of an active materials approach might be beneficial.
• Certification of materials. Participants commented that it appears as if there are substantial costs associ -
ated with certification, and that this frequently is a barrier to using new materials in actual systems. One
participant additionally commented that in the past there were mission requirements to use technologies
that were TRL 6 or higher, whereas the organizations developing push technologies frequently stop at
about TRL 4—this leads to a “valley of death” that is hard to overcome. Finally, there was a comment
from another attendee that improving physics-based modeling is one way to try and streamline certifica -
tion, but there is a need to find a good balance between modeling and testing for certification.
• Reliability. Toward the end of the public discussion session, one workshop participant asked what others
thought about having reliability as a grand challenge for the roadmap. In response, one of the NASA
team members noted that having precise knowledge of the structural reliability is important relative to
integration and saving mass/volume. A workshop attendee also suggested that it is important to consider
whether these technologies are being used because they can, or because they should (e.g., embedded
sensors). He commented that the benefit from embedding sensors in laminates versus metals needs to be
addressed, for example, and that it is important to take a pragmatic approach in applying these technolo -
gies. Another example he provided was self-healing: if a structure has many tubes and holes, there will
be a reduction in strength. He noted that there needs to be a filter applied so that these technologies make
their way onto a vehicle to make it more robust.
REFERENCE
Braun, R., National Aeronautics and Space Administration. 2011. “Investments in Our Future: Exploring Space Through Innovation and Tech-
nology,” presentation at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., May 25, 2011. Available at http://www.
nasa.gov/pdf/553607main_APL_Bobby_5_27_11_DW2.pdf.
