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H
TA05 Communication and Navigation
INTRODUCTION
The draft roadmap for technology area (TA) 05, Communication and Navigation, consists of six level 2 tech -
nology subareas:1
• 5.1 Optical Communication and Navigation
• 5.2 Radio Frequency Communication
• 5.3 Internetworking
• 5.4 Position, Navigation, and Timing
• 5.5 Integrated Technologies
• 5.6 Revolutionary Concepts
The Communication and Navigation TA supports all NASA space missions with the development of new
capabilities and services that make NASA missions possible. Communication links are the lifelines to spacecraft,
providing commanding, telemetry, and science data transfers as well as navigation support. Planned missions
will require a slight improvement in communication data rate, as well as moderate improvements in navigation
precision. However, advancement in communication and navigation technology will allow future missions to
implement new and more capable science instruments, greatly enhance human missions beyond Earth orbit, and
enable entirely new mission concepts. This will lead to more productivity in science and exploration missions, as
well as provide high-bandwidth communications links that will enhance the public’s ability to be a part of NASA
programs of exploration and discovery.
The roadmap describes the communication and navigation technology developments that are necessary to
meet the needs of future missions, provide enhanced capabilities, or enable new mission concepts. This includes
identification of representative future missions and key capabilities and investments that will enable or enhance
these missions. The roadmap focuses on several key issues for the future of communications: development of
radio frequency (RF) technology while initiating a parallel path to develop optical communications capability,
application of Earth’s internetworking technology and processes to reduce operational costs through simplified
1 The draft space technology roadmaps are available at http://www.nasa.gov/offices/oct/strategic_integration/technology_roadmap.html.
167
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168 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
data handling and distribution, improvements in navigation accuracy, development of integrated communication
systems, and identification of potentially revolutionary technologies.
Before prioritizing the level 3 technologies included in TA05, several technologies were renamed, deleted,
or moved. The changes are explained below and illustrated in Table H.1. The complete, revised technology area
breakdown structure (TABS) for all 14 TAs is shown in Appendix B.
TABLE H.1 Technology Area Breakdown Structure for TA05, Communication and Navigation
NASA Draft Roadmap (Revision 10) Steering Committee-Recommended Changes
Two technologies have been merged and one has been renamed.
TA05 Communication and Navigation
5.1. Optical Comm. and Navigation
5.1.1. Detector Development
5.1.2. Large Apertures
5.1.3. Lasers
5.1.4. Acquisition and Tracking
5.1.5. Atmospheric Mitigation
5.2. Radio Frequency Communications
5.2.1. Spectrum Efficient Technologies
5.2.2. Power Efficient Technologies
5.2.3. Propagation
5.2.4. Flight and Ground Systems
5.2.5. Earth Launch & Reentry Comm.
5.2.6. Antennas
5.3. Internetworking
5.3.1. Disruptive Tolerant Networking
5.3.2. Adaptive Network Topology
5.3.3. Information Assurance
5.3.4. Integrated Network Management
5.4. Position, Navigation, and Timing
5.4.1. Timekeeping Merge 5.4.1 and 5.4.2:
5.4.2. Time Distribution Rename: 5.4.1. Timekeeping and Time Distribution
5.4.3. Onboard Autonomous Navigation and Maneuver Delete: 5.4.2. Time Distribution
5.4.4. Sensors and Vision Processing Systems
5.4.5. Relative and Proximity Navigation
5.4.6. Auto Precision Formation Flying
5.4.7. Auto Approach and Landing
5.5. Integrated Technologies
5.5.1. Radio Systems
5.5.2. Ultra Wideband
5.5.3. Cognitive Networks
5.5.4. Science from the Comm. System
5.5.5. Hybrid Optical Comm. and Nav. Sensors
5.5.6. RF/Optical Hybrid Technology
5.6. Revolutionary Concepts
5.6.1. X-Ray Navigation
5.6.2. X-Ray Communications
5.6.3. Neutrino-Based Navigation and Tracking
5.6.4. Quantum Key Distribution
5.6.5. Quantum Communications
5.6.6. SQIF Microwave Amplifier
5.6.7. Reconfigurable Large Apertures Rename: 5.6.7. Reconfigurable Large Apertures Using Nanosat
Constellations
NOTE: Technologies 5.4.1, Timekeeping, and 5.4.2, Time Distribution, have been merged and renamed: 5.4.1 Timekeeping and Time Distribu-
tion because the technologies are very similar and it would be most effective to develop them together. Technology 5.6.7, Reconfigurable Large
Apertures, has been renamed 5.6.7 Reconfigurable Large Apertures Using Nanosat Constellations to better indicate the content of this technol-
ogy as described in the TA05 roadmap.
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169
APPENDIX H
TOP TECHNICAL CHALLENGES
The panel identified three top technical challenges for TA05. They are listed below in priority order.
1. Autonomous and Accurate Navigation: Meet the navigation needs of projected NASA missions by developing
means for more autonomous and accurate absolute and relative navigation.
NASA’s future missions show a diverse set of navigational challenges that cannot be supported with cur-
rent methods. Precision position knowledge, trajectory determination, cooperative flight, trajectory traverse, and
rendezvous with small bodies are just some of the challenges that populate these concepts. In addition, NASA
spacecraft will need to do these things farther from Earth and more autonomously. Proper technology investment
can solve these challenges and even suggest new mission concepts.
2. Communications Constraint Mitigation: Minimize communication data rate and range constraints that impact
planning and execution of future NASA space missions.
A recent analysis of NASA’s likely future mission set indicates that communications performance will need
to grow by about a factor of ten every ~15 years just to keep up with projected robotic mission requirements. A
second dimension of the challenge is measured simply in bits per second. History has shown that NASA mis -
sions tend to return more data with time according to an exponential “Moore’s law.” Missions will continue to be
constrained by the legally allocated international spectral bandwidth. NASA’s S-band is already overcrowded and
there are encroachments at other bands.
Many of the complex things future missions will need to do are hampered by keeping Earth in the real-time
decision loop. Often, a direct link to Earth may not even be available when such decisions are desired. This can
be mitigated by making decisions closer to the platform—minimizing reliance on Earth operations. Advancements
in communications and navigation infrastructure will allow information to be gathered locally and computation to
be performed either in the spacecraft or shared with nearby nodes. Clearly this goal is coupled with the need for
increased autonomy and flight computing.
3. Information Delivery: Provide integrity and assurance of information delivery across the solar system.
Future missions will include international partnerships and increased public interaction. This will imply
increased vulnerability to information compromise. As mentioned in the 2012 Science and Technology Priori -
ties Memo from the White House, NASA needs to “Support cybersecurity R&D to investigate novel means for
designing and developing trustworthy cyberspace—a system of defensible subsystems that operate safely in an
environment that is presumed to be compromised.” As internetworking extends throughout the solar system, the
communications architecture needs to operate in a safe and secure manner.
QFD MATRIX AND NUMERICAL RESULTS FOR TA05
The process used to evaluate the level 3 technologies is described in detail in Chapter 2. The results of the
evaluation are shown in Figures H.1 and H.2, which show the relative ranking of each technology. The panel
assessed four of the technologies as high priority. Three of these were selected based on their QFD scores, which
significantly exceeded the scores of lower ranked technologies. After careful consideration, the panel also desig -
nated 5.5.1 Radio Systems as a high-priority technology.2
2 In recognition that the QFD process could not accurately quantify all of the attributes of a given technology, after the QFD scores were
compiled, the panels in some cases designated some technologies as high priority even if their scores were not comparable to the scores of
other high-priority technologies. The justification for the high-priority designation of all the high-priority technologies for TA05 appears in
the section titled “High Priority Level 3 Technologies,” below.
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170 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
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Alignment Risk/Difficulty
Technology Name Benefit
148 M
5.1.1. Detector Development 3 9 3 1 3 -3 -1
134 M
5.1.2. Large Apertures 3 9 1 0 3 -3 -3
144 M
5.1.3. Lasers 3 9 1 1 3 -3 -1
142 M
5.1.4. Acquisition and Tracking 3 9 1 0 3 -3 -1
136 M
5.1.5. Atmospheric Mitigation 3 9 1 1 3 -3 -3
92 M
5.2.1. Spectrum Efficient Technologies 1 9 3 0 3 -3 -1
126 M
5.2.2. Power Efficient Technologies 1 9 9 3 3 1 -1
58 L
5.2.3. Propagation 1 9 1 1 3 -9 -3
94 M
5
5.2.4. Flight a d G ou d Sys e s
and Ground Systems 1 9 3 1 3 -3
3 -1
56 L
5.2.5. Earth Launch and Reentry Communications 1 9 1 0 3 -9 -3
146 M
5.2.6. Antennas 3 9 3 0 3 -3 -1
168 M
5.3.1. Disruptive Tolerant Networking 3 9 3 3 3 1 -1
188 H
5.3.2. Adaptive Network Topology 3 9 3 3 9 -9 -1
52 L
5.3.3. Information Assurance 1 9 9 0 1 -9 -3
154 M
5.3.4. Integrated Network Management 3 9 3 0 3 -1 -1
200 H
5.4.1. Timekeeping and Time Distribution 3 9 9 3 9 -9 -1
206 H
5.4.3. Onboard Autonomous Navigation and Maneuvering 3 9 3 0 9 -3 -1
146 M
5.4.4. Sensors and Vision Processing Systems 3 9 3 0 3 -3 -1
146 M
5.4.5. Relative and Proximity Navigation 3 9 3 0 3 -3 -1
172 M
5.4.6. Auto Precision Formation Flying 3 3 1 0 9 -3 -1
112 M
5.4.7. Auto Approach and Landing
Auto Approach and Landing 3 3 1 0 3 -3
-3 -1
-1
164 H*
5.5.1. Radio Systems 3 9 3 9 3 -3 -1
148 M
5.5.2. Ultra Wideband Communications 3 3 1 0 9 -9 -1
90 M
5.5.3. Cognitive Networks 3 3 3 3 3 -9 -3
56 L
5.5.4. Science from the Communication System 1 3 0 0 3 -3 -1
58 L
5.5.5. Hybrid Optical Communication and Navigation Sensors 1 3 1 0 3 -3 -1
70 L
5.5.6. RF/Optical Hybrid Technology 1 9 3 1 3 -9 -1
‐23 L
5.6.1. X-Ray Navigation 0 3 0 0 1 -9 -3
‐38 L
5.6.2. X-Ray Communications 0 0 0 0 1 -9 -3
‐62 L
5.6.3. Neutrino-Based Navigation and Tracking 0 0 0 0 1 -9 -9
‐21 L
5.6.4. Quantum Key Distribution 0 3 1 0 1 -9 -3
‐45 L
5.6.5. Quantum Communications 0 3 1 0 1 -9 -9
12 L
5.6.6. SQIF Mi
66 Microwave A lifi
Amplifier 1 3 3 1 1 -9
9 -3
3
5.6.7. Reconfigurable Large Apertures Using Nanosat
4 L
1 3 0 0 1 -9 -3
Constellations
FIGURE H.1 Quality function deployment (QFD) summary matrix for TA05 Communication and Navigation. 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.
CHALLENGES VERSUS TECHNOLOGIES
Figure H.3 shows the relationship between the individual level 3 TA10 technologies and the top technical
challenges. Note that the lowest-priority technologies as determined by QFD rankings tend not to be strongly con -
nected to the top technical challenges. All of the high-priority technologies have a strong connection to two of the
top technical challenges. This shows a good level of consistency between the evaluations and the QFD rankings.
HIGH-PRIORITY LEVEL 3 TECHNOLOGIES
Panel 2 identified four high-priority technologies in TA05. The justification for ranking each of these technolo-
gies as a high priority is discussed below.
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APPENDIX H
0 50 100 150 200 250 300 350 400
5.4.3. Onboard Autonomous Navigation and Maneuvering
High Priority
5.4.1. Timekeeping and Time Distribution
5.3.2. Adaptive Network Topology
5.4.6. Auto Precision Formation Flying
Medium Priority
5.3.1. Disruptive Tolerant Networking
5.5.1. Radio Systems
5.3.4. Integrated Network Management
5.1.1. Detector Development
5.5.2. Ultra Wideband Communications
5.2.6. Antennas
5.4.4. Sensors and Vision Processing Systems
5.4.5. Relative and Proximity Navigation
5.1.3. Lasers
5.1.4. Acquisition and Tracking
5.1.5. Atmospheric Mitigation
5.1.2. Large Apertures
5.2.2. Power Efficient Technologies
5.4.7. Auto Approach and Landing
5.2.4. Flight and Ground Systems
5.2.1. Spectrum Efficient Technologies
5.5.3. Cognitive Networks
5.5.6. RF/Optical Hybrid Technology
Low Priority
5.2.3. Propagation
5.5.5. Hybrid Optical Communication and Navigation Sensors
5.2.5. Earth Launch and Reentry Communications
5.5.4. Science from the Communication System
5.3.3. Information Assurance
5.6.6. SQIF Microwave Amplifier
5.6.7. Reconfigurable Large Apertures Using Nanosat Constellations
5.6.4. Quantum Key Distribution
5.6.1. X‐Ray Navigation
5.6.2. X‐Ray Communications
High Priority (QFD Score Override)
5.6.5. Quantum Communications
5.6.3. Neutrino‐Based Navigation and Tracking
FIGURE H.2 Quality function deployment rankings for TA05 Communication and Navigation.
Technology 5.4.3, Onboard Autonomous Navigation and Maneuvering Systems
Onboard autonomous navigation and maneuvering (OANM) techniques are critical for improving the capabili-
ties and reducing the support requirements for many future space missions. By accurately determining the position
and attitude of the vehicle, the dependence on routine position fixes from Earth will be greatly reduced, freeing the
communication network for other tasks. The onboard maneuver planning and execution monitoring will increase
the vehicle agility, enabling new mission capabilities currently not possible given the round-trip time delay to Earth
and the loss of communication during atmospheric reentry. It could also reduce costs by helping to eliminate the
large work force required to support the routine operations of the spacecraft.
Given the previous flight demonstrations, e.g., DS-1 and EO-1, some basic aspects of the OAMN are at TRL
9, but the new advanced capabilities required for future missions are closer to a TRL of 3. The research and flight
demonstrations needed for this technology to be accepted for future missions are well aligned with the NASA
experience and capabilities and consistent with NASA’s past roles.
It is possible that NASA will be able to draw upon new algorithms and capabilities resulting from the significant
current interest in autonomous robotics and UAVs, but the mission and autonomy requirements in these domains
differ significantly from NASA’s needs. There is more overlap with Department of Defense work on autonomous
underwater robotics, given the truly remote operations with limited off-board communication capabilities that
often exist. However, given the length, variety, and complexity of the missions, the challenges faced by NASA
are unique and it is very unlikely that they will be fully addressed by an external research organization. As such,
NASA investment in this technology area is critically important.
The panel determined that the OANM systems provide a major benefit due to the technology’s potential to sig -
nificantly improve the capabilities/performance and reduce the operational cost of future missions. The alignment
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172 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
Top Technology Challenges
1. Autonomous and Accurate
Navigation: Meet the 2. Communications Constraint
3. Information Delivery:
Mitigation: Minimize
navigation needs of projected
Provide integrity and
communication data rate and
NASA missions by developing
assurance of information
range constraints that impact
means for more autonomous
delivery across the solar
planning and execution of
and accurate absolute and
system.
future NASA space missions.
relative navigation.
Priority TA 05 Technologies, Listed by Priority
● ●
5.4.3. Onboard Autonomous Navigation and Maneuvering
H
● ●
5.4.1. Timekeeping and Time Distribution
H
○ ● ●
5.3.2. Adaptive Network Topology
H
○ ● ●
5.5.1. Radio Systems
H
○
5.4.6. Auto Precision Formation Flying
M
○ ○
5.3.1. Disruptive Tolerant Networking
M
○ ○
5.3.4. Integrated Network Management
M
○
5.1.1. Detector Development
M
○
5.5.2. Ultra Wideband Communications
M
○
5.2.6. Antennas
M
○
5.4.4. Sensors and Vision Processing Systems
M
○
5.4.5. Relative and Proximity Navigation
M
○ ○
5.1.3. Lasers
M
○ ○
5.1.4. Acquisition and Tracking
M
○ ○
5.1.5. Atmospheric Mitigation
M
○
5.1.2. Large Apertures
M
○ ○
5.2.2. Power Efficient Technologies
M
○
5.4.7. Auto Approach and Landing
M
○ ○
5.2.4. Flight and Ground Systems
M
○ ○
5.2.1. Spectrum Efficient Technologies
M
○ ○
5.5.3. Cognitive Networks
M
○ ○
5.5.6. RF/Optical Hybrid Technology
L
○
5.2.3. Propagation
L
○ ○
5.5.5. Hybrid Optical Comm. and Nav. Sensors
L
○
5.2.5. Earth Launch and Reentry Commmunications
L
5.5.4. Science from the Comm. System
L
○
5.3.3. Information Assurance
L
5.6.6. SQIF Microwave Amplifier
L
5.6.7. Reconfigurable Large Apertures using Nanosat Constellations
L
5.6.4. Quantum Key Distribution
L
○
5.6.1. X-Ray Navigation
L
5.6.2. X-Ray Communications
L
5.6.5. Quantum Communications
L
5.6.3. Neutrino-Based Navigation and Tracking
L
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 little or no impact in
[blank]
addressing the challenge.
FIGURE H.3 Level of support that the technologies provide to the top technical challenges for TA05 Communication and
Navigation.
to NASA’s needs is high because it will impact deep space exploration with crew, robotic science missions,
planetary landers and rovers. The alignment with other aerospace needs is considered to be medium, as some of
the automation and planning algorithms will overlap with the DOD/commercial space missions and other robotic
applications, but the alignment with national needs is considered to be low as this work will really only be relevant
to spacecraft. The risk is assessed to be moderate to high, within the bounds of NASA’s acceptable risk levels for
technology development. Of particular importance is the observation that the autonomous navigation and maneuver
planning algorithms can be added (and verified) incrementally on near-term missions to enable a solid foundation
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APPENDIX H
to be established for future missions. This approach could be used to appropriately scale the workforce required
to address the OANM technology challenges at a moderate level of effort. Due to the potential for major mission
improvements and cost savings, strong alignment with NASA needs, and reasonable risk and development effort,
OANM are rated as high-priority technologies.
Technology 5.4.1, Timekeeping and Time Distribution
NASA provides communications and navigation infrastructure for its missions. Underlying this infrastructure
are atomic clocks and time transfer hardware and software. New, more precise atomic clocks operating in space,
as well as new and more accurate means of time distribution and synchronization of time among such atomic
clocks (e.g., optical transmitters and receivers operating in the space environment), will enable the infrastructure
improvements and expansion NASA requires in the coming decades.
The TRL of timekeeping and distribution systems varies over a wide range from 9 for current systems all the
way down to 1 for yet-to-be-proposed atomic clocks. Ground-based work3 at the National Institute of Standards
and Technology (NIST) and other laboratories can be considered TRL 3-4. The planned ISS experiment ACES 4
is a scientific instrument, not routine PNT gear; TRL 3 is probably a good estimate for the status of ACES when
considered for use in an operational scenario.
Precision timekeeping and transfer is of interest not only to NASA but also to the defense and communica -
tion industries as well as the scientific community. NASA has expertise in timekeeping and distribution in space
systems via the Deep Space Network and the TDRSS. NASA collaborations with DOD, NIST, university labs,
and international partners such as France and Japan will be fruitful. (Japan, France, NIST, and JPL are partners in
ACES mentioned above.) NASA, with appropriate partners, could focus on miniaturizing laboratory prototypes,
providing the necessary stable mechanical and thermal environment, and increasing the longevity and reliability
of precision clocks and time transfer equipment. The ISS may play a role in development of timekeeping and
distribution technology by providing a microgravity environment in which the technologies can be demonstrated.
However, for missions beyond LEO, hardware demonstration at high radiation levels and algorithms appropriate
to solar system navigation are needed.
Advances in timekeeping and distribution of several orders of magnitude were judged to provide major benefits,
since increased precision of timekeeping and transfer leads to increased precision of relative and absolute position
and velocity which in turn provides better starting solutions to enable autonomous rendezvous, docking, landing,
and formation flying remote from Earth. In addition, precision timekeeping enables new tests of fundamental
physics, time and frequency metrology, geodesy, gravimetry, and ultra-high-resolution VLBI science applications.
Alignment with NASA’s needs is considered high due to the substantial impact of the technologies to multiple
missions in multiple mission areas including human and robotic spaceflight involving rendezvous, relative station
keeping and landing missions. Similarly there is high alignment with other aerospace and non-aerospace national
needs, as the benefit of precise timekeeping and synchronization of navigational and communications equipment
grows with the explosive increase of data required by modern technology. The risk associated with development
of precision timekeeping and distribution is judged to be moderate to high, a good fit for NASA’s technology
development program. Due to their major benefits, alignment with NASA and other national needs, and reasonable
risk and development effort, precision timekeeping and time distribution are rated as high-priority technologies.
Technology 5.3.2, Adaptive Network Topology
Adaptive Network Topology (ANT) is the capability for a network to change its topology in response to
either changes or delays in the network, or additional knowledge about the relationship between the communica -
tion paths. This technology area includes technologies to improve mission communication such as ad hoc and
mesh networking, methods of channel access, and techniques to maintain the quality of signal across dynamic
3 See http://www.nist.gov/pml/div688/logicclock_020410.cfm.
4 See http://www.spaceflight.esa.int/users/downloads/factsheets/fs031_10_aces.pdf.
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174 NASA SPACE TECHNOLOGY ROADMAPS AND PRIORITIES
networks to assure successful exchange of information needed to accommodate increased mission complexity and
achieve greater mission robustness. The goal is to improve end-to-end rather than hop-to-hop performance. This
was originally pursued for commercial uses. However, optimization in terrestrial networks with this method has
been mostly abandoned, replaced by adding additional tall towers and other hubs. The fall in terrestrial equipment
prices has obviated the need for optimization inside of a limited network.
The TRL for these technologies are within the 2-5 range. They have been demonstrated in the laboratory,
but no commercial or space implementation has been realized. While of strong academic interest, it is unlikely
that any practical development will be done by commercial entities. However, government entities with extreme
applications, such as underwater communications, are likely to pursue these capabilities. Investments within DOD
are happening, but the constraints may be sufficiently different to be incompatible with NASA interests. While
the basic research might be purchasable from academic or research interests sponsored by the National Science
Foundation and others, applicable technology will not. Because of the lack of commercial need, NASA participation
is necessary if this technology is to be developed to a level that can support NASA missions in the next decades.
Access to the ISS is not a requirement for development in this technology area. The applicability of this tech -
nology potentially crosscuts all missions where the end-points do not have direct line of sight communications.
The distinction between disruptive tolerant networking (DTN) and ANT is debatable. The panel views DTN as a
subset of ANT and this view is, in part, responsible for the high priority of ANT.
The panel rated the alignment with NASA needs very high for this technology. The benefit to NASA is derived
because future multi-element missions will require advanced network topologies which will need to be adaptive
in order to remain robust for their applications. A high rating in the category of technical risk and reasonableness
was given since this is a significant extension of prior capability, with associated risk. However, the level of risk
has been mitigated by a variety of prior, small scale research projects by a number of government agencies such
as DOD, the National Science Foundation, and even the National Institute for Occupational Safety and Health in
the mining industry (especially following accidents). A low score for sequencing and timing stems mainly from
the fact that a mission need schedule is not well defined for this technology.
Technology 5.5.1, Radio Systems
Radio systems technology focuses on exploiting technology advances in RF communications, PNT, and space
internetworking to develop advanced, integrated space and ground systems that increase performance and efficiency
while reducing cost. For example, a multipurpose software defined radio might be developed that can change its
function with mission phase and requirements. While this technology can benefit from individual advancements in
many of the other level 3 technologies in TA05 (antennas, atmospheric mitigation, large apertures, power efficient
technologies, spectrum efficient technologies, propagation, Earth launch and reentry communication systems, and
information assurance), this entry focuses on the challenges associated with integration of these advancements into
operational systems.
Advancements in radio systems integration focus on one of the highest priority technical challenges within
TA05: Minimize communications constraints on data rate and range that impact planning and execution of future
NASA space missions. Like all technologies in TA05, these advancements benefit multiple types of missions in
deep space as well as near-Earth orbit.
Software defined radios (SDRs) are a prime example of the challenges of integration for radio systems. These
offer frequency agility and wide frequency coverage, but require broadband circuitry, broadband antennas, and
sophisticated software to drive the system. While the component technologies in each of these areas are mature,
integration into flight-worthy systems is still required before widespread adoption of SDRs becomes possible.
SDRs can be configured for many applications such as radar, arrays for beamforming, direction finding, signal
identification, etc.
The radio astronomy community has substantial overlap with the technologies for future SDR implementations
for receiving telescopes. The Allen Telescope Array (ATA) of the SETI Institute and the University of California
at Berkeley is a prototype of what may become the standard in radio astronomy. In this case, Allen provided
development funding to the SETI Institute through proof of principle and initial operations, but a lack of ongoing
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APPENDIX H
operational funding caused the array to be mothballed. The technologies implemented in the ATA can be applied
to future transmitting telescopes as well, and would be a tremendous enhancement of the capabilities of the Deep
Space Network. While NASA can leverage techniques and technologies from the ATA, transmitting is atypical for
the radio astronomy community and will require technology investments from NASA and others.
Active antenna elements are needed for smart transmitting arrays, which could also be used for a smart receiv -
ing array. It would also be useful in future relay networks and orbiting communication networks, which would
enable ground users to form beams in several different directions simultaneously. This provides the following
substantial simultaneous benefits: Covering large fractions of the sky on a wide range of frequencies (wavelengths
of meters to millimeters); tracking or searching for multiple targets simultaneously; and nulling-out discrete or
extended sources of interference while receiving faint signals from sources with only small separations in look angle
and measuring their spectra, Doppler shifts, and angular structure. With this technology, NASA could improve the
data rates and efficiency of communication with deep space missions, including enabling high-rate communica -
tion with multiple missions simultaneously. It would also reduce the need for detailed scheduling of access to the
antennas and receivers, as they can be operated simultaneously.
Receiving arrays have a current TRL of ~6, but transmitting arrays are closer to the TRL 2-3 range. There may
be component technologies in radar systems that can be applied to transmitting arrays, but these will need to be
demonstrated in an integrated fashion to achieve a higher TRL. The DOD has highly versatile, broadly applicable
radar systems that can perform many of these same functions, but to our knowledge the applicability of these
systems to NASA-unique needs has not been addressed.
The ISS could be used as a platform for space-based testing of new SDR integrated systems, but it is not
an ideal platform due to the noisy RF environment and the number of arrays, radiators, and modules that inhibit
directional line-of-sight communications. Much of the development and systems integration can be performed on
the ground, especially for future Deep Space Network systems. But for space-based applications such as relay
networks or formations of small satellites, the technology would get as much, if not more, benefit from initial
testing on any orbiting vehicle.
NASA has the expertise to take a leading role in the development of radio systems, software defined radios,
and array telescopes. While some advancements could come from DOD and the National Reconnaissance Office
efforts, NASA has unique requirements for low signal levels and demanding angular resolution that will not be
reflected in outside agency work. Given that the commercial cell phone industry is interested in applications for
future generations of cognitive radios as well, NASA could pursue joint development projects, or at minimum
remain cognizant of advances made within these industries and organizations.
The steering committee assessed the benefit of radio systems technologies to result in major mission perfor-
mance improvements due to the potential to improve throughput, versatility, and reliability with lower impact on
the host spacecraft in terms of size, weight, and power (SWAP). The alignment to NASA needs is high because
improvements in communication systems will impact nearly every NASA spacecraft, including near-Earth, deep
space, and human exploration missions. The alignment with other aerospace needs is moderate due to its potential
impact on DOD and commercial spacecraft. The alignment with other national needs is high, as it could impact
any terrestrial industry that uses radios, WiFi, cable, internet, and other communications technologies. The risk is
assessed to be low to moderate, as previously developed prototypes have already demonstrated key technologies at
the component or subsystem level. The remaining challenge is to integrate these with NASA communications and
complete space qualification of the integrated systems. The panel overrode the QFD score for this technology to
designate it as a high-priority technology because the QFD scores did not capture the value of this technology in
terms of the system level advances that would occur with major improvements in radio systems.
MEDIUM- AND LOW-PRIORITY TECHNOLOGIES
TA05 includes 30 level 3 technologies that ranked low or medium priority.
In this roadmap, two technologies (5.4.6 Autonomous Precision Formation Flying and 5.5.2 Ultra Wideband)
were assessed to be medium priority because of limited alignment within multiple NASA mission areas. While
several potential missions (e.g., fractionated satellites or missions with multiple spacecraft, burst transmissions
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between nearby spacecraft) were identified, the technologies were not broadly applicable to multiple missions in
multiple NASA mission areas.
Seven other medium-priority technologies were judged to provide major improvements in mission perfor-
mance, but were assessed to have a lower risk level than is usually appropriate for NASA OCT technology invest -
ments. These technologies included 5.3.1 Disruptive Tolerant Networking, 5.3.4 Integrated Network Management,
5.2.6 Antennas, 5.4.4 Sensors and Vision Processing Systems, 5.4.5 Relative and Proximity Navigation, 5.1.3
Lasers, and 5.1.5 Atmospheric Mitigation. For most of these technologies, the development risk is low because
the underlying technology is well understood, and a gradual development program focused on advances in these
areas could be formulated, tested, and applied incrementally.
Five additional medium-priority technologies were also judged to provide major improvements in mission per-
formance with broad applicability to multiple NASA missions, but development cost and cost risk were a concern.
These technologies included 5.1.1 Detector Development, 5.1.4 Acquisition and Tracking, 5.1.2 Large Apertures,
5.4.7 Auto Approach and Landing, and 5.5.3 Cognitive Networks. Despite the potential for significant benefits,
these technologies were assessed to have a high probability of encountering pitfalls which could complicate the
effort and cause additional development problems, possibly leading to significant cost growth and schedule delays.
The remaining three medium-priority technologies and six low-priority technologies were judged to have only
minor benefits to NASA missions within the next 20 to 30 years. These technologies included 5.2.2 Power Efficient
Technologies, 5.2.4 Flight and Ground Systems, 5.2.1 Spectrum Efficient Technologies, 5.5.6 RF/Optical Hybrids,
5.2.3 RF Propagation, 5.2.5 Earth Launch and Reentry Communication, 5.5.5 Hybrid Optical Communication and
Navigation Sensors, 5.5.4 Science from the Communication System, and 5.3.3 Information Assurance. Each of
these technologies falls into at least one of two categories: (1) technologies that are fairly mature with limited room
for additional improvements (e.g., 5.2.3 RF Propagation) or (2) technologies where even substantial improvements
in component or subsystem technology will not easily translate into order-of-magnitude improvements in mission
performance or mission risk (e.g., 5.5.3 Information Assurance).
The remaining seven low-priority technologies were judged to be so immature or impractical that no benefit
is projected in the 20- to 30-year timeframe of interest. These technologies were all part of the Revolutionary
Concepts section of the roadmap, and include 5.6.6 SQIF Microwave Amplifiers, 5.6.7 Reconfigurable Large
Apertures Using Nanosat Constellations, 5.6.4 Quantum Key Distribution, 5.6.1 X-Ray Navigation, 5.6.5 Quantum
Communications, 5.6.2 X-Ray Communications, and 5.6.3 Neutrino-Based Navigation and Tracking.
The panel noted technologies where investment from other organizations outside NASA would overshadow
any potential NASA investments. When this is the case, NASA’s limited funds could be better spent on areas where
DOD, international space agencies, or commercial industry are not making substantial financial contributions. This
impacts technologies such as 5.3.1 Disruption Tolerant Networking, 5.3.4 Integrated Network Management, and
5.1.5 Atmospheric Mitigation. NASA’s key work in these areas could focus on adapting advances made by other
organizations to the specific requirements of NASA missions.
OTHER GENERAL COMMENTS ON THE ROADMAP
All NASA missions require communication and navigation to some degree, so the priorities developed in this
section are mostly independent of the mission mix. For some missions, advances in communication throughput
could enable them to carry more advanced, high-data rate instruments with significant science benefit (e.g., hyper -
spectral imagers). Similarly, improvements in navigation accuracy, when coupled with coordinated improvements
in guidance, autonomy, sensors, and EDL technologies, will enable high precision pinpoint landing on planetary
surfaces. But in most cases, the prioritization of communication and navigation technologies is not impacted by
specific missions in the mission model.
PUBLIC WORKSHOP SUMMARY
The workshop for the TA05 Communication and Navigation technology area was conducted by the Robot -
ics, Communications, and Navigation Panel on March 29, 2011, at the Keck Center of the National Academies,
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Washington, D.C. The discussion was led by panel chair Stephen Gorevan. 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 this introduction, the day started with an overview
of the NASA roadmap by the NASA authors, followed by several sessions addressing the key areas of the road -
map. For each of these sessions, experts from industry, academia, and/or government were invited to provide a 30
to 45 minute presentation/discussion 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 presentation by the NASA roadmap development team identified challenges faced by future interplan -
etary missions, and described how improved communications and navigation can mitigate these challenges. From
a technology development portfolio standpoint, the key challenge is ensuring that advancements in communica -
tion and navigation are out ahead of new missions, so that the technology is sufficiently advanced that it can be
incorporated in future missions without adversely impacting the critical path.
The existing roadmap was developed using a previous decadal survey, but a new one was released a few
weeks before the workshop. NASA recognized the need to update the roadmap to reflect the new decadal survey,
but they did not feel this would substantially change the technologies in the roadmap. Even without pull from
specific future missions, NASA indicated that they would pursue the same technology list to ensure that current
technology would stay ahead of potential communication and navigation demand. The discussions mostly focused
on the challenges for deep-space (interplanetary) communication and navigation, though some near-Earth-space
solutions for optical communication repeaters were described.
NASA outlined the issues for each of the level 2 WBS subareas: optical communication and navigation; RF
communication; internetworking; position, navigation, and timing (PNT); and revolutionary concepts. Within each
subarea, the presentation described the current state of the art, recent advancements, desired future developments,
and mission-level impact. Challenges identified include laser pointing and stabilization (optical communication
subarea), communication through challenging RF environments such as rocket plumes and reentry ionization (RF
communication), utilizing arrays of antennas to increase the effective aperture (RF communication), onboard
computing’s mass/power/volume constraints as they relate to onboard routing (internetworking), and autonomy
for navigation (PNT).
NASA mentioned that the integration of optical communications and disruption-tolerant networking (DTN)
offers combined benefits that are stronger than each one alone. The DTN program is structured around near-term
improvements in single-hop DTN, which will demonstrate benefits to automation rather than networking. Rather
than scripting data transfers with manual downlink plans, DTN would allow for this to happen automatically
onboard the vehicles. This provides a motivation for DTN even without a vision for a deep-space multi-node
network of relays.
After NASA’s presentation, a brief discussion period allowed the panel and interested members of the general
public to ask questions of the NASA presenters. There were questions about the composition of future missions
in the latest roadmaps, internetworking simulators, deep-space infrastructure for internetworking, networking
interoperability/compatibility with international partners, technologies and architectures for space-to-ground opti -
cal communications, technology hurdles for pinpoint landing, and prioritization/linking of technologies within the
roadmap.
Briefing 1: Satellite Networking
Eylem Ekici (Ohio State University) provided a brief background of his work in wireless communication net -
works, wireless network analysis and modeling, and protocol development. His comments on the TA05 roadmap
focused primarily on the internetworking section. He stated that the roadmap captured the most important existing
projects and test cases, but also emphasized the room for growth in this subarea. He believes there is significant
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potential for research and development in space-based networking, which can take advantage of terrestrial improve-
ments in autonomous network operations for ad hoc mesh networks.
Ekici identified disruption tolerant networking as the most critical challenge and a game-changing capability
within the roadmap. However, he feels that existing work on DTN is insufficient to address needs of actual space
missions due to poorly partitioned objectives, assets, functions, and interoperability. In addition, he believes that
work on adaptive network topology should be a part of a forward-looking vision for networking, including work
on requirements analysis, general network architectures, and protocol and solution development. While he felt that
information assurance was important for medium-term applications, existing solutions (or new solutions developed
by other agencies) are likely to address about 90 percent of NASA’s challenges at very low cost to the agency.
In the question and answer session following his presentation, there were questions about the suitability of
space-qualified, radiation-hardened electronics for networking applications. Existing commercial and government
hardware typically have issues with radiation including single event upsets and latchups. Because NASA deep
space missions operate in a much higher radiation environment than missions in LEO and GEO, there may be
hardware-based challenges to implementing space networking solutions. Ekici indicated that there are likely to
be hardware/processing issues that will have to be addressed, and recommended that this work occur in parallel
with the networking and protocol development.
Briefing 2: Optical Communications
Gary Swenson (University of Illinois at Urbana Champaign) followed Ekici’s presentation with a discussion
on observations generated by himself and a group of professors at UIUC with backgrounds in fiber lasers, quan -
tum electronics, and optical remote sensing. Based on the background of the involved professors, this assessment
focused on TA 5.1 Optical Communication and Navigation. They identified laser transmitters as a key challenge
for optical communication, including desired improvements in weight, reliability, and efficiency. Secondary chal -
lenges in this area are laser beam expanders, the uniformity of the beam in single mode, and methods for mitigat -
ing atmospheric disturbance of the beam. For high bandwidths, sensor efficiencies, dark current (cooling), and
amplifiers are all areas recommended for improvement.
As a technology development effort, Swenson recommended that NASA address methods to extend the life -
time of optical communication components, including reducing susceptibility to damage by energetic particles
and reducing fiber degradation/darkening over time. However, Swenson also stated that NASA’s highest near-
term priority should be performing an in-space demonstration of optical communications systems, rather than
component-level improvements in apertures or atmospheric turbulence mitigation.
Swenson also identified optical communications as low risk, but during the discussion period he clarified that
this was low risk for near-term demonstration objectives. For long-term objectives with very large receivers, NASA
needs to better understand the sensitivity and efficiency issues before a realistic assessment of the development
risk can be made.
There was additional discussion about the need for a local sync for generating path lengths between optical
arrays on the ground. NASA indicated that they had some discussion on this subject while generating the roadmap,
but the technical details were not addressed in the roadmap document itself. This was recognized as an area that
will require additional simulation before an appropriate assessment of risk can be made.
Briefing 3: Guidance and Control
Mimi Aung (JPL) presented an assessment of TA05 from a guidance, navigation, and control perspective. She
identified four classes of next-generation missions that will drive improvements in guidance and control: (1) precision
landing for large bodies (reducing the landing error ellipse, autonomous safety); (2) landing on small bodies and
primitive bodies; (3) formation flying (including swarms and distributed clusters); and (4) autonomous rendezvous
and docking. Together, these missions will drive the need for onboard autonomous target-relative GN&C, multiple-
spacecraft GN&C, and onboard target-relative navigation sensors. In all of these, target-relative navigation was
identified as a key technology challenge. Aung indicated that improvements in GN&C will stress current onboard
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computing elements, and recommended that NASA invest in advanced computing (including multi-core processing
and field-programmable gate arrays, or FPGAs) to keep pace with the demand for additional processing.
Aung stated that improvements in this area will require both subsystem and system demonstrations, includ -
ing development and utilization of ground-based integrated testbeds and on-orbit demonstrations. Currently, each
mission has to develop its own testbed; future efforts could focus on developing an open-architecture adaptable
hardware-in-the-loop integrated testbed which could be re-used for multiple applications. Aung also mentioned that
JPL feels that the integration of individual technology pieces into a high-functioning system will be a challenge
on par with individual technology developments. JPL believes that an integrated test of precision EDL should be
a higher priority than advancement of specific pieces. (This echoed the importance of system-level testing from
Swenson’s previous presentation.) Several other workshop participants echoed this response, emphasizing the
possible advantages of moderate-performance technologies that work well when integrated over the absolute best
component technology.
However, other comments from the public described a desire to focus the roadmap on technologies that OCT
could bring to TRL 6, rather than integrated capabilities that were more program-specific (e.g., radiation-hardened
FPGAs rather than terrain-relative navigation (TRN)). TRN as a discipline is more important for NASA to invest in,
but each mission will still require substantial customization for their applications and operational concepts, which
limits the effectiveness of investments in general TRN capabilities. Similarly, other public comments recommended
that general-purpose testbeds could be developed by the programs/missions, rather than an independent technol -
ogy program. The panel pointed out that science missions are focused much more on science than on technology,
and are not generally interested in spending limited program resources on technology maturation. If the testbed
or general-purpose research is not funded by a technology organization, the science program is unlikely to do it.
Aung recommended adding a new section to the roadmap dedicated to autonomous integrated GN&C. This led
to significant discussion on this approach, and highlighted the need to address the topic of GN&C in an integrated
fashion. Currently, navigation is carried under TA05, but guidance and control is split between TA04 (Robotics,
Tele-Robotics, and Autonomous Systems) and TA09 (Entry, Descent, and Landing).
Briefing 4: X-Ray Navigation
Darryll Pines (University of Maryland at College Park) described the X-ray NAVigatation and Autonomous
Position (XNAV) program that he ran while he was at DARPA from 2003 to 2006. This presentation focused on
only one technology: 5.6.1 X-Ray Navigation. Pines described the motivation for using pulsars as navigation
beacons, and described potential accuracies of 24 to 36 meters in Earth orbit for long-duration observations, and
accuracies less than a kilometer at other locations in the solar system. Newly researched navigation algorithms can
provide accurate along-track solutions using the measured Doppler delay in the X-ray pulses. According to Pines,
XNAV offers benefits over GPS due to the higher theoretical accuracy from short wavelengths (with appropriate
clock updates from the ground), utility throughout the solar system, inherent radiation hardening, and robustness
to radiation damage, jamming, and contamination. Because of these benefits, there have been several follow-on
programs including the X-ray Timing program at DARPA and several smaller NASA programs. One drawback of
XNAV is that past systems required instruments on the order of a few square meters in cross-section and approxi -
mately 25 to 50 kg in weight. Recent developments, however, have improved detector signal-to-noise sensitivity
and reduced the size, weight, and volume of prototype navigation instruments. Nevertheless, greater position and
attitude accuracy will require improvements in X-ray photon detection and optics to produce instruments small
enough for deep space navigation.
Briefing 5: Deep-Space Navigation
Lincoln Wood (JPL) provided a briefing with comments on specific sections of the roadmap that impact
accuracy and performance of deep space navigation. Wood assessed the roadmap as conservative in estimates of
deep space navigation accuracy for single antenna applications (e.g., line-of-sight Doppler and ranging) as well
as multi-antenna applications (very long baseline array). In addition to new technologies related to frequency and
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timing, Wood stated that advancements in SWAP for existing capabilities/components should be technologies in
themselves, and should be reflected in the roadmap alongside new capabilities. He stated that any game-changing
capability would likely result from evolutionary advances with existing technologies, rather than revolutionary
technologies.
Wood’s assessment of the top technical challenges (within the frequency and timing section of the roadmap)
include improvements in high-performance clocks (stability, SWAP, and reliability), oscillators, and space quali -
fied lasers. These imply high-priority technology advancements in (1) improving frequency and timing reference
sources by advancing the TRL, making SWAP advancements, and improving reliability, and (2) making reliability
and SWAP improvements (rather than improving performance) for optical metrology hardware. Mercury ion atomic
clocks were identified as a component technology near a tipping point, and neutrino navigation was identified as
unfeasible on any kind of realistic development timescale.
During the question and discussion phase, Wood recommended that NASA place navigation beacons around
places of interest and locations that will be visited at higher frequencies, such as the Moon, Mars, Titan, and other
locations.
Briefing 6: Mission Design and Navigation
Alberto Cangahuala (JPL) provided inputs on the roadmap’s treatment of navigation for lunar and interplan -
etary applications. In this area, Cangahuala identified top technical challenges as: (1) high-fidelity modeling to
mitigate the impact of long round-trip light times on numerical precision, (2) reducing onboard resources (mass,
power, and delta-V) required for guidance and navigation, and (3) boot-strapping required to accrue necessary
detailed environmental characterization information for target bodies. He also identified several trends for modern
navigation systems, including the challenges of route planning for low-thrust systems, low-energy transfers, prox -
imity operations, satellite and planetary tours, and operations in unstable and/or unknown dynamical environments.
As a result of these trends, modern missions require a stronger integration of flight path and attitude control (i.e.,
coupling of control knowledge and thrust), highlighting the need for more onboard autonomy (both fully integrated
systems and navigation “apps” that take advantage of existing flight system capabilities).
Cangahuala identified mission/trajectory design as a potential technology gap in the roadmap. This is a cross-
cutting capability with parts in modeling and simulation and navigation. Navigation and mission/trajectory design
are connected by a common need for consistent modeling for planetary and spacecraft dynamics, and mission/
trajectory design can minimize navigation uncertainties as part of a design process. Within this field, high-priority
challenges include improving the speed, agility, and robustness of trajectory optimizers and investigating new
trajectory mechanisms (e.g., invariant manifolds, cycler trajectories).
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.
• Synergy with DOD investments. Some technologies in the roadmap may be synergistic with elements in
the DOD. This includes a near-term experiment on atmospheric dynamics, knowledge about space-based
IP-networking (though information assurance is a challenge), specific TWTA and SSPA component
technologies, and minimization of SWAP for existing technologies. While some of these were tied to the
now-cancelled TSAT program, other efforts in these areas are ongoing. NASA and DOD may benefit
from working together on these technologies, or at least remaining cognizant of developments made by
the other organization. NASA was encouraged to participate in the Space Industrial Council’s Critical
Technologies Working Group, which addresses inter-agency technology development efforts. This could
be a mechanism for NASA to communicate with their DOD counterparts and identify high-TRL develop -
ment items that NASA could productize to claim early successes for OCT.
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• International involvement. Based on a question about international cooperation, a representative from
NASA OCT clarified that the near-term focus of the NRC is prioritization of the technologies, regard -
less of who matures them. At some point in the future, OCT will address the potential overlap between
NASA’s priorities and other organizations, but this will not be part of the NRC’s charter.
• Systems engineering framework. A workshop participant stated that the roadmaps illustrate component
technologies, but lack a systems engineering framework to identify synergies between technologies (espe-
cially between different roadmaps). OCT responded that they will do this kind of strategic integration
over the next 12 months, and that the NRC is not being asked to do this.
• Technology pull from future missions. There was some discussion about how realistic the missions in the
roadmap were. Many of the target missions may not be funded, and may not have high enough priority to
become real. Participants discussed the value of using a more realistic assessment of potential missions,
so that a better rationale for market pull (versus technology push) can be identified.
• Industrial base. For navigation components (e.g., fiber-optic gyros, atomic clocks), there are potential
industrial base/market size issues that may drive NASA toward a particular solution. There are only a few
vendors in these areas, and some are not doing well and could strongly benefit from NASA developmental
funding.
