2

High-Priority Technologies

INTRODUCTION

As noted in Chapter 1, 42 level 3 technologies in the 2015 roadmaps meet the criteria for review in this report. Thirty-nine of these technologies are new: They do not appear in either the 2010 or the 2012 TABS. The other three appear by number in NASA’s 2015 TABS and the TABS recommended in the 2012 National Research Council (NRC) report,¹ but there has been a major change to the naming and content of these technologies, so they are being evaluated again. The 42 technologies evaluated by this study are listed below by technology area (TA) and technology subarea:

TA 1, Launch Propulsion Systems (11 new technologies)

1.1, Solid Rocket Propulsion Systems

1.1.6, Integrated Solid Motor Systems

1.1.7, Liner and Insulation

1.6, Balloon Launch Systems

1.6.1, Super-Pressure Balloon

1.6.2, Materials

1.6.3, Pointing Systems

1.6.4, Telemetry Systems

1.6.5, Balloon Trajectory Control

1.6.6, Power Systems

1.6.7, Mechanical Systems: Launch Systems

1.6.8, Mechanical Systems: Parachute

1.6.9, Mechanical Systems: Floatation

TA 4, Robotics and Autonomous Systems (11 new technologies)

4.2, Mobility

4.2.5, Surface Mobility

4.2.6, Robot Navigation

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¹ NRC, 2012, NASA Space Technology Roadmaps and Priorities: Restoring NASA’s Technological Edge and Paving the Way for a New Era in Space, The National Academies Press, Washington, D.C.

4.2.7, Collaborative Mobility

4.2.8, Mobility Components

4.3, Manipulation

4.3.7, Grappling

4.4, Human–System Interaction

4.4.3, Proximate Interaction

4.4.8, Remote Interaction

4.5, System-Level Autonomy

4.5.8, Automated Data Analysis for Decision Making

4.7, Systems Engineering

4.7.3, Robot Modeling and Simulation

4.7.4, Robot Software

4.7.5, Safety and Trust

TA 5, Communications, Navigation, and Orbital Debris Tracking and Characterization Systems (4 new technologies)

5.1, Optical Communications and Navigation

5.1.6, Optical Tracking

5.1.7, Integrated Photonics

5.7, Orbital Debris Tracking and Characterization Systems

5.7.1, Tracking Technologies

5.7.2, Characterization Technologies

TA 7, Human Exploration Destination Systems (1 new technology)

7.4, Habitat Systems

7.4.4, Artificial Gravity

TA 9, Entry, Descent, and Landing Systems (3 new technologies)

9.2, Descent and Targeting

9.2.6, Large Divert Guidance

9.2.7, Terrain-Relative Sensing and Characterization

9.2.8, Autonomous Targeting

TA 11, Modeling, Simulation, Information Technology, and Processing (8 new technologies)

11.2, Modeling

11.2.6, Analysis Tools for Mission Design

11.3, Simulation

11.3.5, Exascale Simulation

11.3.6, Uncertainty Quantification and Nondeterministic Simulation Methods

11.3.7, Multiscale, Multiphysics, and Multifidelity Simulation

11.3.8, Verification and Validation

11.4, Information Processing

11.4.6, Cyber Infrastructure

11.4.7, Human–System Integration

11.4.8, Cyber Security

TA 13, Ground and Launch Systems (3 new technologies)

13.1, Operational Life Cycle

13.1.4, Logistics

13.2, Environmental Protection and Green Technologies

13.2.5, Curatorial Facilities, Planetary Protection, and Clean Rooms

13.3, Reliability and Maintainability

13.3.8, Decision-Making Tools

TA 14, Thermal Management Systems (1 new technology)

14.3, Thermal Protection Systems

14.3.2, TPS Modeling and Simulation

There are no new technologies in the following technology areas:

• TA 2, In-Space Propulsion Technologies
• TA 3, Space Power and Energy Storage
• TA 6, Human Health, Life Support, and Habitation Systems
• TA 8, Science Instruments, Observatories, and Sensor Systems
• TA 10, Nanotechnology
• TA 12, Materials, Structures, Mechanical Systems, and Manufacturing

All of the technologies in the roadmap for TA 15 Aeronautics are new, because the 2010 and 2012 TABS did not include aeronautics. As noted in Chapter 1, however, TA 15 is outside the scope of this study.

This chapter describes the results of the committee’s effort to prioritize the 42 new (or heavily revised) technologies using the same prioritization process that the NRC used in developing the 2012 report. As described in the following sections, the committee added 5 of the 42 to the list of 83 high-priority level 3 technologies from the 2012 NRC report.² The five technologies (listed in order of the technology number) are as follows:

4.3.7, Grappling

4.4.8, Remote Interaction

9.2.7, Terrain-Relative Sensing and Characterization

9.2.8, Autonomous Targeting

14.3.2, TPS Modeling and Simulation

In the discussion of technologies below, the greatest detail is provided for these five high-priority technologies, and the least amount of detail is provided for those technologies that are ranked as a low priority. For all of the technologies, additional information is available in the 2015 NASA Technology Roadmaps.³

Table 2.1 provides the complete list of 88 technologies that the committee determined are a high priority: 83 from the 2012 NRC report plus the 5 listed above, which are shaded.

UNDERSTANDING THE TABLES

In each of the sections that follow, there is a table that shows the scores for each technology that were used to determine its priority. These tables were created by taking the corresponding table from the 2012 NRC report and inserting the new technologies evaluated in this report. The first column lists the technologies. The last two columns show the score and the priority (high, medium, or low) assigned to each technology. Appendix C, in the section 2012 NRC Report: Process to Identify the High-Priority Technologies, provides a detailed explanation of the intervening columns and the quality function deployment (QFD) process that formed the basis for the scoring.

In the tables and figures, the priority of each technology is designated as L (low priority), M (medium priority), H (high priority), or H* (high priority, QFD override). As described in Appendix C, the steering committee and panels who authored the 2012 NRC report had the option of ranking key technologies as a high priority even

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² NRC, 2012, NASA Space Technology Roadmaps and Priorities.

³ NASA, “2015 NASA Technology Roadmaps,” Washington, D.C., available at http://www.nasa.gov/offices/oct/home/roadmaps/index.html, accessed June 20, 2016.

TABLE 2.1 The 88 High-Priority Level 3 Technologies—83 from the 2012 NRC Report^a and 5 More from This Report, Which Are Shaded

^a National Research Council, 2012, NASA Space Technology Roadmaps and Priorities: Restoring NASA’s Technological Edge and Paving the Way for a New Era in Space, The National Academies Press, Washington, D.C.

^b Fault detection, isolation, and recovery.

^c Guidance, navigation, and control.

NOTES:

1. Technologies are listed by roadmap/technology area (TA 1 through TA 14; there are no high-priority technologies in TA 13). Within each technology area, technologies are listed in descending order by the quality function deployment (QFD) score assigned by the panels that helped to author the 2012 report. This sequencing may be considered a rough approximation of the relative priority of the technologies within a given technology area.

2. Except for the five new technologies, the name of each technology in this table is as it appears in the original list of 83 high-priority technologies in the 2012 NRC report. In some cases, the names have been slightly revised for the 2015 TABS (see Appendix B). Two technologies have been deleted and do not appear in the 2015 TABS: 8.2.4, High Contrast Imaging and Spectroscopy Technologies, and 8.2.5, Wireless Spacecraft Technologies. Three technologies have been renumbered: 5.4.3, 11.2.4a, 12.5.1, above, have been renumbered as 5.4.2, 11.2.4, and 12.4.5, respectively, in the 2015 TABS.

if they did not have a numerical score that corresponded to a high priority rank. These override technologies were deemed by the panels to be high priority irrespective of the numerical scores. In the tables and figures for each technology area in this chapter, the override technologies are designated by an “H*”.

TA 1, LAUNCH PROPULSION SYSTEMS

In the 2012 NRC report, TA 1 included all propulsion technologies required to deliver space missions from the surface of Earth to Earth orbit or Earth escape, including solid rocket propulsion systems, liquid rocket propulsion systems, air breathing propulsion systems, ancillary propulsion systems, and unconventional/other propulsion systems. The 2015 NASA technology roadmaps for TA 1 expanded the scope to include suborbital balloon technologies. Table 2.2 shows how the new technologies fit into the TA 1 TABS. The scoring and ranking of all TA 1 technologies are illustrated in Figures 2.1 and 2.2.

TABLE 2.2 TA 1, Launch Propulsion Systems: Technologies Evaluated

Technology 1.1, Solid Rocket Propulsion Technologies

Two new technologies in solid rocket propulsion systems were evaluated, and both were ranked as a medium priority.

Technology 1.1.6, Integrated Solid Motor Systems

A new five-segment advanced solid rocket booster is being developed for the Space Launch System (SLS) Block 1, which is derived from the Space Shuttle’s four-segment solid rocket booster. An advanced booster option for SLS Blocks 1b and 2 is necessary to meet the payload requirement of 130 metric tons. Three options exist to meet this need, one of which is an advanced solid rocket booster.

Technology for integrated solid motor systems is fairly mature, and relatively minor improvements are needed. However some improvements are enabling for applicable missions. Also, the level 4 research task Nano Launch Vehicle Solid Motor Stage looks promising for a wide variety of missions. This technology is ranked as a medium priority.

Technology 1.1.7, Liner and Insulation

Health concerns and supply issues have mandated that nonasbestos liners and insulation be developed for solid rocket systems. While there are existing “green” Kevlar-based liners and insulations, they do not meet NASA’s requirements. This problem can and must be solved for the applicable missions. A material (polybenzimidazole acrylonitrile butadiene rubber, or PBI NBR) has been identified, and the path forward is clear. This technology is ranked as a medium priority.

Technology 1.6, Balloon Launch Systems

The Science Mission Directorate has a stable of flight options, one of which is provided by the NASA Balloon Program. Currently operational balloons support large payload volumes, payload masses up to 3,600 kg, and flights of up to 60 days at altitudes over 30 km. Nine technologies to improve balloon capabilities were reviewed.

Medium-Priority Balloon Launch Technologies

Technologies 1.6.1, Super-Pressure Balloon, and 1.6.5, Balloon Trajectory Control, were ranked as a medium priority because they enable ultralong-duration balloon flights that would increase the scientific value of NASA’s balloon program. Super-pressure balloons as well as super-pressure in combination with zero-pressure balloon vehicles offer the possibility of much longer flights (up to 100 days) and flights at a larger variety of latitudes. However, much of the technical risk has been alleviated because a smaller super-pressure balloon has already flown. Balloon trajectory control may be required to enable longer duration flights at midlatitudes by helping to avoid overflight of populated areas and to reach safe termination locations, thereby avoiding the need to prematurely terminate flights.

Low-Priority Balloon Launch Technologies

Technologies 1.6.2, Materials; 1.6.3, Pointing Systems; 1.6.4, Telemetry Systems; 1.6.6, Power Systems; 1.6.7, Mechanical Systems: Launch Systems; 1.6.8, Mechanical Systems: Parachute; and 1.6.9, Mechanical Systems: Floatation were ranked as a low priority because they primarily address engineering problems (that is, implementing identified technical solutions) rather than technology challenges (that is, developing new technical solutions). As a result, these technologies have a lower priority than other elements of the technology roadmaps that more directly address technology challenges.

TA 4, ROBOTICS AND AUTONOMOUS SYSTEMS

TA 4 includes 11 new level 3 technologies. Many of these technologies are categorized as new as a result of a new organization of the TA 4 technologies from the previous roadmaps. Table 2.3 shows how the new technologies fit into the TA 4 TABS. The scoring and ranking of all TA 4 technologies are illustrated in Figures 2.3 and 2.4.

While all of the new TA 4 technologies are important to robotics, 2 of the 11 new technologies were ranked as high priority (4.3.7, Grappling, and 4.4.8, Remote Interaction), 5 were ranked as a medium priority (4.2.5, Surface Mobility; 4.2.6, Robot Navigation; 4.2.8, Mobility Components; 4.7.4, Robot Software; and 4.7.5, Safety and Trust), and 4 were ranked as a low priority (4.2.7, Collaborative Mobility; 4.4.3, Proximate Interaction; 4.5.8, Automated Data Analysis for Decision Making; and 4.7.3, Robot Modeling and Simulation).

Technology 4.3.7, Grappling

Grappling systems are ranked as a high priority because they enable the physical capture of small asteroids and asteroid-sourced boulders, the attachment of said objects to robotic spacecraft, and the capture of free-flying spacecraft. Grappling technology would thereby support the transport of asteroids from their natural orbit to a lunar orbit, the human collection and return of samples from a boulder in lunar orbit, orbital debris mitigation, the protection of Earth from small planetary bodies, and assembly of large spacecraft in orbit for future exploration missions. Potential commercial uses include securing boulder-sized asteroid samples for detailed sampling or processing in commercial space resources operations and securing dead satellites for return, disposal, salvage, or repair. The recent signing of the U.S. Commercial Space Launch Competitiveness Act, which entitles U.S. citizens to any asteroid or space resource obtained (or grappled and returned) from an asteroid may spur interest in commercial asteroid mining. Even so, NASA’s development of grappling technology is a high priority because related work by other government organizations and industry is unlikely to meet NASA-specific needs, especially in light of the Asteroid Retrieval Mission schedule.

The content of technology 4.3.7, Grappling, overlaps somewhat with 4.6.3, Docking and Capture Mechanism/Interfaces. The focus of technology 4.6.3, however, is focused on docking of one spacecraft with another, whereas the scope of 4.3.7 also includes interactions with natural objects, such as asteroids and boulders from asteroids. Asteroids are massive tumbling targets with unstructured physical properties, and new grappling technologies will be needed to capture either a small asteroid or a boulder from a larger asteroid.

The alignment of technology 4.3.7 to NASA’s needs is very high because NASA is developing the first robotic mission to visit a large near-Earth asteroid. The goal of the mission is to grapple and collect a multi-ton boulder

TABLE 2.3 TA 4, Robotics and Autonomous Systems: Technologies Evaluated

from its surface and redirect the boulder into a stable orbit around the moon. Once there, astronauts would again employ grappling technologies to explore the boulder and return to Earth with samples in the 2020s.

The International Space Station (ISS) could be an effective platform for evaluating and testing the performance of the electromechanical elements of grappling systems. Reliability testing of the grappling capture and preload systems could be conducted inside or outside the ISS.

The lack of detail in the TA 4 roadmap for this technology is a concern. Only a single level 4 research task was proposed, and its description gives little additional detail over the level 3 description. A potential level 4 research task of interest would be nonrigid approaches to grappling large, spinning structures. For example, grapples attached to adjustable tethers could perhaps be used to immobilize a spinning object and secure it to the spacecraft (or secure the spacecraft to the object).

Technology 4.4.8, Remote Interaction

Remote Interaction is a high-priority technology because it would provide control and communication methods that enable humans to remotely operate otherwise autonomous systems and robots. Control includes teleoperation, supervisory control, and other control strategies. Remote Interaction includes supervisory control technology, which is ranked as a high priority in the 2012 NRC report.⁴ As stated in the 2012 report, supervisory control incorporates techniques necessary for controlling robotic behaviors using higher-level goals instead of low-level commands, thus requiring robots to have semiautonomous or autonomous behaviors. Supervisory control increases the number of robots a single human can simultaneously supervise, reducing costs. This technology also reduces the impacts of time delays on remotely supported robotic teams, improving the synergy of combined human–robot teams, and facilitating teams of distributed robots. This technology will support the design of game-changing science and exploration missions, such as new robotic missions at remote locations and simultaneous robotic missions with reduced human oversight.

In addition to supervisory control, 4.4.8, Remote Interaction, also includes technology to enable manual control of remote systems and to enable operators to monitor system status, assess task progress, perceive the remote environment, and make informed operational decisions. These technologies are compatible and complementary to supervisory control technologies, and successful systems for remote operations must integrate all these technologies. Appropriate visualization, interfaces, and decision support for situation assessment are necessary to enable smooth transitions between supervisory and manual control, as required by the task. This capability to transition between modes is particularly important in performing novel tasks or in responding to unanticipated situations. Technology for remote operations that integrate supervisory control, manual control, and effective interfaces will enable realization of efficient and productive remote operations.

As noted in the 2012 NRC report, limited supervisory control has been deployed for the Mars rovers, so that the basic capabilities have a high TRL (9) but the advanced capabilities have a relatively low TRL (2-3). The alignment to NASA’s needs is high due to the impact of reducing the number of personnel required to supervise robotic missions and the number of science and exploration missions to which the technology can be applied. Remote interaction generally has applications across the government agencies, including the Departments of Defense, Energy, and Homeland Security. For example, submersible unmanned vehicles can encounter time delays while under water; although the range of time delays of interest for submersible unmanned vehicles is different than the range of time delays of interest to space applications. Thus, NASA is uniquely positioned to lead the maturation of this technology to TRL 6. There may also be opportunities on some aspects of this technology for NASA to collaborate with both industry and international partners, such as Japan, France, and Germany.

The alignment with other aerospace and national needs is considered to be moderate, since the results can impact remote interaction for any robotic system. The risk is assessed as moderate to high, based on the fact that providing for remote interaction is a systems engineering problem. Thus development of the technology is highly

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⁴ Supervisory Control is technology 4.4.2 in the TABS recommended by National Research Council, 2012, NASA Space Technology Roadmaps and Priorities: Restoring NASA’s Technological Edge and Paving the Way for a New Era in Space, The National Academies Press, Washington, D.C.

dependent on the development of underlying robotic and human–machine interaction capabilities. The program will need to leverage existing NASA and DOD capabilities to ensure timely development of various related technologies, such as robust, autonomous behaviors.

Medium-Priority TA 4 Technologies

Technologies 4.2.5, Surface Mobility; 4.2.6, Robot Navigation; 4.2.8, Mobility Components; 4.7.4, Robot Software; and 4.7.5, Safety and Trust, were ranked as a medium priority. All have the potential to make major improvements in robotic technology applicable to multiple missions. The factors that kept them from being high priority were primarily that (1) there was not a clear plan for addressing their technical hurdles, (2) NASA has already successfully demonstrated some relevant technology on flight missions, and/or (3) there is substantial work being done in these areas outside of NASA that could easily be incorporated by NASA. Thus it is not a high priority for NASA to have a leading role in these areas. Tremendous amounts of work related to 4.2.5, Surface Mobility; 4.2.6, Navigation; 4.7.4, Robot Software; and 4.7.5, Safety and Trust, are under way outside of NASA, although terrestrial use requirements differ from NASA’s requirements. Technology 4.2.8, Mobility Components, while more NASA unique, had a mix of level 4 research tasks that either had already been largely achieved (e.g., wheels for planetary surfaces) or were lacking a clear plan for achievement.

Low-Priority TA 4 Technologies

Technologies 4.2.7, Collaborative Mobility, and 4.5.8, Automated Data Analysis for Decision Making, were ranked as low priority because the proposed level 4 research tasks did not seem likely to provide significant improvement to robotics technology or they are not on the critical path for the design reference missions (DRMs). These general categories are all important, but substantial work is being done in these areas outside of NASA. The proposed work was either not critical to the DRMs or not NASA specific and thus could be taken from similar work being done by industry or other agencies.

Technology 4.4.3, Proximate Interaction, is a technology area of great interest to robotics, particularly with regard to industrial, service, and assistive technology applications where robots interact with humans. However, this technology was ranked as low priority because the proposed level 4 work did not appear to be NASA specific. The DRMs do not appear to require proximate interaction technology beyond the capabilities already demonstrated by NASA. The improvement in NASA operations to extend proximate operations into new areas of NASA operations did not appear to be of great benefit during the time frame of this roadmap. It may be important to transfer and adapt technology from the technology robotics domain in the future, but this is not an urgent requirement.

Technology 4.7.3, Robot Modeling and Simulation, was ranked as a low priority. While modeling and simulation are critical, the proposed level 4 research tasks are not NASA specific and are actively being pursued by the Department of Agriculture, DOD, and other agencies. The NASA-specific aspects would be using the simulation in remote operations, but all of the proposed work is basically supercomputer-level simulations. Thus the methods and types of models are not specific to NASA and the benefit of a NASA effort in this domain is not a high priority.

TA 5, COMMUNICATION, NAVIGATION, AND ORBITAL DEBRIS TRACKING AND CHARACTERIZATION SYSTEMS

The 2015 NASA roadmap for TA 5 Communications, Navigation, and Orbital Debris Tracking and Characterization Systems expands the scope of this technology area from that presented in the TABS in the 2012 NRC report by adding a new level 2 technology subarea, 5.7, Orbital Debris Tracking and Characterization. This new technology subarea incorporates two new level 3 technologies: 5.7.1, Tracking Technologies, and 5.7.2, Characterization Technologies. Two other level 3 technologies have been added: 5.1.6, Optical Tracking, and 5.1.7, Integrated Photonics. Table 2.4 shows how the new technologies fit into the TA 5 TABS. The scoring and ranking of all TA 5 technologies are illustrated in Figures 2.5 and 2.6.

All four of the new TA 5 level 3 technologies were evaluated to be of medium priority.

TABLE 2.4 TA 5, Communications, Navigation, and Orbital Debris Tracking and Characterization Systems: Technologies Evaluated

Technology 5.1.7, Integrated Photonics

Technology 5.1.7, Integrated Photonics, is ranked as a medium priority, although it is the most promising of the new level 3 technologies in TA 5. It has wide applicability for shorter range intersatellite communications links for near-Earth applications and networked communications to planetary orbiters with deep space communications capabilities. It may also offer marginal integration and test improvements for deep space communications systems requiring large optical power amplifiers. Moreover, the range of NASA applications goes beyond communications to include sensors such as LIDARs for docking and autonomous landing and active science instruments for wind measurements, particle characterization, vibrometry, and so on.

The overall QFD ranking is consistent with rankings from the previous study for similar and related technologies such as 5.1.3, Lasers (144), and 5.1.1, Detector Development. Unlike the very specialized development required for observatory and science instruments, there are substantial outside development efforts in integrated photonics driven by the terrestrial fiber optic network. An international community of telecommunications companies and government consortia are investing heavily in 5.1.7, reducing the development risk for NASA. As a result, 5.1.7, Integrated Photonics, is ranked as a medium-priority technology. This is not to say that NASA should not be investing as well, but this investment could be more focused on NASA-unique aspects, in particular on reliability and radiation tolerance of telecom products operating in various space environments. There may also be program/science requirements for integrated photonics operating at wavelengths or waveforms other than those used for terrestrial fiber-optic systems.

Technology 5.7.1, Tracking Technologies

Technology 5.7.1, Tracking Technologies, is also considered to be relatively important within the set of medium-priority technologies. This is largely driven by increasing awareness of the problem that orbital debris poses for NASA space operations, particularly in low Earth orbit, where the ISS or Earth-sensing satellites can be exposed to debris with considerable differential velocities. Addressing this problem will require development of new, low-TRL approaches to deal with the challenging problems of searching, tracking, and cataloging a dynamic debris environment ranging over several magnitudes in size. The committee notes that the proposed set of level 4 research tasks currently does not adequately reflect these challenges. Nonetheless, while the problem is potentially significant, the committee chose to rank this as a medium priority for NASA investment given extensive efforts by other U.S. government organizations and the European Space Agency. Explicitly referencing these efforts in NASA’s roadmap would facilitate coordination.

Technologies 5.1.6, Optical Tracking, and 5.7.2, Characterization Technologies

Although 5.1.6, Optical Tracking, and 5.7.2, Characterization Technologies, were both ranked as a medium priority, they scored substantially lower than two other new TA 5 technologies, above. Technologies needed to implement optical tracking are covered by other level 3 technologies, such as low-jitter focal plane arrays that can count individual photons (5.1.1), large apertures (5.1.2), and exquisite timing (5.4.1). No technical challenges were identified for 5.7.2, Characterization Technologies, which focuses on modeling the debris environment. Coordination of NASA’s efforts in this area with other organizations would prevent duplication and validate the results of NASA’s research.

TABLE 2.5 TA 7, Human Exploration Destination Systems: Technologies Evaluated

There is high likelihood that investment from other organizations outside NASA could overshadow any potential NASA investments in three of the new TA 5 technologies: 5.1.7, Integrated Photonics; 5.7.1, Tracking Technologies; and 5.7.2, Characterization Technologies. Given this situation, NASA’s limited resources could be better applied elsewhere.

TA 7, HUMAN EXPLORATION DESTINATION SYSTEMS

The 2015 NASA draft roadmap for technology area TA 7, Human Exploration Destination Systems, adds one new level 3 technology: 7.4.4, Artificial Gravity. Table 2.5 shows how this technology fits into the TA 7 TABS. The scoring and ranking of all TA 7 technologies are illustrated in Figures 2.7 and 2.8.

Technology 7.4.4, Artificial Gravity

Artificial gravity (7.4.4) was determined to be a low-priority technology with the current understanding of the potential of other gravity countermeasures outlined in technology 6.3.2 Long-Duration (Crew) Health. NASA is investigating approaches to mitigate the risks of long-duration exposures to microgravity environments through exercise and other countermeasures that would cost much less than developing spacecraft with artificial gravity. Artificial gravity uses centripetal forces to simulate gravitational forces either by rotating the crew on a centrifuge within a spacecraft or by rotating the spacecraft as a whole (Figure 2.9). Apparatuses that rotate individuals and that do not impact the overall design of the spacecraft fall within the scope of TA 6, Human Health, Life Support, and Habitation Systems (specifically, research task 6.3.2.1, Artificial Gravity), which is evaluated in the 2012 NRC report.

The greatest technical challenges to artificial gravity involve understanding (1) spacecraft design modifications required to accommodate rotation and (2) the positive and negative impacts of artificial gravity. A key prerequisite is understanding the degree and duration of partial gravity necessary to counteract various human health issues associated with long-term exposure to zero or microgravity.⁵ Full development of artificial gravity technology would require one or more full-scale in-space demonstrations, and it might require a requalification of all other vehicle systems. This endeavor will likely remain a low priority unless and until currently proposed microgravity countermeasures prove ineffective.

TA 9, ENTRY, DESCENT, AND LANDING SYSTEMS

The 2015 NASA roadmap for TA 9, Entry, Descent, and Landing Systems, realigned many level 3 technologies that appeared in the TABS in the 2012 NRC report. The 2015 TA 9 roadmap reports that the only work to support 7 of the 17 level 3 TA 9 technologies in the TABS recommended by the 2012 NRC report now falls under other

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⁵ The long-term effects of partial gravity on the surface of the Moon or Mars are also unknown, but this issue is outside the scope of technology 7.4.4.

technologies, which in many cases belong to other TAs. Of particular note, technology 9.4.7, Guidance, Navigation, and Control (GN&C) Sensors and Systems, was the highest ranked TA 9 technology in the 2012 NRC report, and it was designated as one of the 16 highest priority technologies. The 2015 TA 9 roadmap, however, reports that there is no system-level work proposed for 9.4.7, though some contributing technology is being proposed under two preexisting technologies (9.1.3, Rigid Hypersonic Decelerators, and 9.1.4, Deployable Hypersonic Decelerators) and three new technologies (9.2.6, Large Divert Guidance; 9.2.7, Terrain-Relative Sensing and Characterization; and 9.2.8, Autonomous Targeting). These three new technologies were the subject of the committee’s evaluation, and Table 2.6 shows how they fit into the TA 9 TABS. The scoring and ranking of all TA 9 technologies are illustrated in Figures 2.10 and 2.11.

Two of the three new level 3 technologies were evaluated to be of high priority (9.2.7 and 9.2.8), which is consistent with the 2012 NRC report that ranked GN&C as a high priority. Technology 9.2.6 was ranked as low priority.

TABLE 2.6 TA 9, Entry, Descent, and Landing Systems: Technologies Evaluated

Technology 9.2.7, Terrain-Relative Sensing and Characterization

Technology 9.2.7, Terrain-Relative Sensing and Characterization, is the most promising of the new level 3 technologies. This technology would produce “high-rate, high-accuracy measurements for algorithms that enable safe precision landing near areas of high scientific interest or predeployed assets.”⁶ It is a game-changing technology that could enable important new missions not currently feasible in the next 20 years. It impacts multiple missions in multiple mission areas, both human and robotic. With the flyby of Pluto completing an initial remote-sensing survey of the major objects in our solar system, NASA is continuing planetary exploration with a new era of increased surface exploration. This technology will help enable many such missions in this new era, such as human and robotic Mars missions, sample return missions, and a Europa lander.

This technology also has a broad impact across the aerospace community, already influencing commercial and military autonomous vehicles, such as the rapid advancement of unmanned air vehicles. For example, this technology is helping to develop systems that allow a single operator simultaneously to oversee the operation of a distributed set of vehicles. Both this technology and 9.2.8, Autonomous Targeting, which are highly coupled, enhance autonomous capabilities by reducing the dependence of onboard systems on human operators.

The technology risk, which is moderate to high, is a good fit for a NASA technology project in terms of both time frame and feasibility, and there are well-developed plans for its execution.

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⁶ NASA, 2015, NASA Technology Roadmaps: TA 9 Entry, Descent, and Landing Systems, Washington, D.C., p. TA 9-25.

Technology 9.2.8, Autonomous Targeting

The algorithms associated with technology 9.2.8, Autonomous Targeting, are tightly coupled to the sensors of technology 9.2.7, above. Technology 9.2.8 is likewise a game-changing technology that would enable important new missions not currently feasible in the next 20 years, such as several of the New Frontier missions. It would also enhance multiple missions in multiple mission areas, both human and robotic. By improving the ability of vehicles to assess and characterize the terrain they are facing for landing and exploration, this technology would enable the next step of autonomous targeting, which could be critical when interplanetary distances make remote guidance difficult or impossible. Even if a vehicle is piloted for a human mission, this technology could be critical for a safe landing.

This technology was ranked only slightly lower than 9.2.7 in terms of its impact on the aerospace community, where it was still expected to impact a fairly large subset. It will not have as broad an applicability as 9.2.7 since the algorithms in this area are expected to be much more specific to NASA applications, though it will still have some applicability to commercial and military autonomous vehicles. It is expected that this technology, like 9.2.7, will have less influence on nonaerospace applications. The technology risk is also moderate to high, but it is a good fit for the NASA technology projects both in time frame and feasibility, with well-developed plans for its execution.

Technology 9.2.6, Large Divert Guidance

Technology 9.2.6, Large Divert Guidance, would develop new guidance algorithms to enable substantial changes in the lateral direction of a vehicle during reentry for a divert capability of 1 to 10 km. This technology is considered a low priority owing to the minimal improvement it would make in mission capability and the likely mass penalties for the divert propulsion required. The applicability of this technology is limited to a small number of missions, and large divert capability is not necessarily required for precision landing. Completing development of this technology would be a major effort with extremely high risk. The TA 9 roadmap states that a mission demonstration of a full-scale system is required before this technology would be flown on an operational mission. Plans for development of this technology also were not very well defined.

TA 11, MODELING, SIMULATION, INFORMATION TECHNOLOGY, AND PROCESSING

The 2015 NASA roadmap for TA 11, Modeling, Simulation, Information Technology, and Processing, expands the scope of this technology area beyond that presented in the TABS in the 2012 NRC report by adding eight new level 3 technologies. Table 2.7 shows how these new technologies fit into the TA 11 TABS. The scoring and ranking of all TA 11 technologies are illustrated in Figures 2.12 and 2.13.

Two of the eight new level 3 technologies (11.2.6, Analysis Tools for Mission Design, and 11.3.7, Multiscale, Multiphysics, and Multifidelity Simulation) were evaluated to be of medium priority; the other six new technologies were ranked as low priority.

TABLE 2.7 TA 11, Modeling, Simulation, Information Technology, and Processing: Technologies Evaluated

Technology 11.3.7, Multiscale, Multiphysics, and Multifidelity Simulation

Technology 11.3.7, Multiscale, Multiphysics, and Multifidelity Simulation, is ranked as the most promising of the new TA 11 technologies. It promises the benefits of increasing the span of dimensional scales and fidelity of predictions, thereby improving the understanding, design, and optimization of physical systems that possess a hierarchical interdependence of physical processes. The TA 11 roadmap says that simulations that would be developed as part of this technology would contribute to “the development of lighter and more durable structural materials; higher performing materials for fuel cells, nuclear reactors, batteries, and solar cells; and new multifunctional materials that combine these functions. The simulations also have application to understanding reactive

flows found within engines and surrounding airframes at hypersonic speeds.”⁷ The contribution that advances in this technology will make to the above applications remains to be seen. In any case, the committee did not rank 11.3.7 as a high-priority technology largely because other private and government entities are developing the underlying technologies. Although NASA can contribute to its development and pursue applications to specific problems and systems, it is not necessary for NASA to take the lead in technology development.

Technology 11.3.5, Exascale Simulation, which is ranked as a low priority, will eventually be an important component of 11.3.7 by bringing in much greater computing capacity. Exascale capability (1,000 petaflops) is being developed in laboratories in several countries and is supported by the U.S. National Strategic Computing Initiative. It is predicted to be available within the next 5 to 7 years. By closely watching developments in exascale computing, NASA would be prepared to anticipate and implement it as it becomes available. Both 11.3.5 and 11.3.7 were components of technology 11.2.4a Science Modeling and Simulation in the 2012 NRC report, which

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⁷ NASA, 2015, NASA Technology Roadmaps: TA 11 Modeling, Simulation, Information Technology, and Processing, Washington, D.C., p. TA 11-38.

was given a high priority. Technologies 11.2.4a and 11.2.4b, Aerospace Engineering Modeling and Simulation have been merged as 11.2.4, Science Modeling, in the 2015 NASA TABS.

Technology 11.2.6, Analysis Tools for Mission Design

Technology 11.2.6, Analysis Tools for Mission Design, is also ranked as a medium priority. These tools could enhance current mission design capabilities and improve NASA’s management of its technology portfolio. As missions become more complex and distributed, integrated mission design tools are better equipped to reach optimum designs than the current mixture of commercial-off-the-shelf systems and selected systems from previous missions. In addition to the benefit of optimum mission design, advanced analysis tools have the potential of improving the estimates of both cost and risk. Analysis Tools for Mission Design was not ranked as a high-priority technology largely because it represents an enhancement over current practice rather than an enabling component for new missions.

Low-Priority Technologies

The other new TA 11 technologies were all ranked as a low priority: 11.3.5, Exascale Simulation, is being developed by other private and government entities. As noted above, NASA could continue to watch advances in this area rather than becoming more involved in it. Technology 11.3.6, Uncertainty Quantification and Nondeterministic Simulation, could potentially improve the robustness of cost controls and mission by reducing uncertainties in many aspects of mission design and development. However, concepts such as mathematical descriptions of uncertainty that are consistent with the true state of knowledge of the system are still fairly abstract and in need of basic research efforts, which NASA could watch until they become more suitable for application to its own specific problems. Technology 11.3.8, Verification and Validation, as applied to software, modeling, and simulation, is already an ongoing activity and could be steadily improved. While it is important and relevant, it is not clearly in need of major investment. Improvements in technology 11.4.7, Human–System Integration, will become more important for future deep-space missions in which crew autonomy will need to increase in order to reduce dependence on ground-based control. Many different approaches have been proposed to improve human–system integration, and many concepts are already being defined in mission design activities. As focused areas of particular interest are identified, higher priority targets for significant investment will probably emerge. Technologies 11.4.6, Cyber Infrastructure, and 11.4.8, Cyber Security, were ranked as low priority because, while important to NASA, both are of vital importance to a great many organizations in government and industry. Given the level of investment that others are making, NASA is better suited to be a user rather than a developer of these technologies.

TA 13, GROUND AND LAUNCH SYSTEMS

The 2015 NASA roadmap for TA 13 Ground and Launch Systems expands the scope of this technology area from that presented in the TABS in the 2012 NRC Report by adding three new level 3 technologies: 13.1.4, Logistics; 13.2.5, Curatorial Facilities, Planetary Protection, and Clean Rooms; and 13.3.8, Decision-Making Tools. Table 2.8 shows how the new technologies fit into the TA 13 TABS. The scoring and ranking of all TA 13 technologies are illustrated in Figures 2.14 and 2.15.

TABLE 2.8 TA 13, Ground and Launch Systems: Technologies Evaluated

As in the previous NRC review of TA 13, none of the new TA 13 technologies was ranked as high priority. Technologies 13.1.4 and 13.3.8 were ranked as a low priority primarily because the benefit of each technology would be minor. While ground and launch systems are significant contributors to mission life cycle costs, the primary innovations are being made by commercial providers for which NASA is serving as a competitive catalyst and a customer rather than as a developer. Technology 13.2.5, Curatorial Facilities, Planetary Protection, and Clean Rooms, is important to planetary surface missions in that it would facilitate ground operations and reduce the need for heat-resistant flight hardware. Planetary protection would also be a key element of a robotic Mars sample return mission or a human mission to the Mars surface. However, like the other new TA 13 technologies, 13.2.5 is not an urgently needed, game-changing technology, and it is ranked as a medium priority.

TA 14, THERMAL MANAGEMENT SYSTEMS

The 2015 NASA draft roadmap for technology area TA 14, Thermal Management Systems, adds one new level 3 technology, 14.3.2 TPS Modeling and Simulation, which replaces a section with the same technology

number—14.3.2 Plume Shielding (Convective and Radiative)—that appeared in the 2012 NRC TABS and the 2010 NASA TABS. Table 2.9 shows how the new technology fits into the TA 14 TABS. The scoring and ranking of all TA 14 technologies are illustrated in Figure 2.16 and 2.17.

Technology 14.3.2, Thermal Protection System Modeling and Simulation

The rationale for the new 14.3.2 TPS Modeling and Simulation is that uncertainties in the modeling of strong radiative shocks are a major limitation in the design of effective heat shields for high-speed entry into the

TABLE 2.9 TA 14, Thermal Management Systems: Technologies Evaluated

atmospheres of Earth, Mars, and other bodies. This technology would address major challenges that remain in the physics-based modeling of entry shocks, thermal radiation, and their interaction with an ablating heat shield. Early TPS design was largely empirical, based on extensive direct (and expensive) testing in Earth’s atmosphere. Testing in ground test facilities is also difficult and expensive because of the extreme environments associated with atmospheric entry. Computational methods employing physics-based models are improving to the point that with validation via laboratory and flight testing and verification, they can more reliably predict TPS performance. However, further development is required to build confidence that design margins can be substantially reduced and that weight savings will be realized. Major challenges remain in increasing the accuracy and precision of physics-based modeling of entry shocks, thermal radiation, and their interaction with an ablating heat shield, challenges that are addressed by this technology. Currently, uncertainties are +80 percent to –50 percent for Mars return missions; missions to other destinations have different uncertainty ranges.⁸ The goal of proposed research for technology 14.3.2 is to reduce uncertainty below 25 percent for all planetary missions. This reduction in uncertainty would enable the use of heat shields that weigh less, thereby reducing spacecraft weight and/or increasing allowable payload weight.

Although the QFD score for this technology fell within the range of medium priority scores for TA 14, it ranks as the highest scoring medium-priority technology in TA 14, and the committee concluded that this technology is a high priority and ranks it as such. This technology couples closely with the 2012 highly ranked cross-cutting technology of X.5, Entry, Descent, and Landing TPS, which includes both rigid and flexible systems. For that technology to advance and realize its potential, the modeling must improve.

As noted in the roadmap for TA 14, “a significant challenge facing the development of this technology is the limitations in the available flight and ground test data” (p. TA 14-93). The committee endorses the suggestion made by the 2012 committee and other groups that more opportunities to obtain these critical flight data should be realized to validate modeling efforts.

The QFD scores rank this level 3 technology only at the medium level. However, the committee classified 14.3.2 as a high-priority override technology given that the technology is very important to any NASA mission that includes atmospheric entry and given the rate of advancement in the multiphysical modeling of shockwave phenomena. The development of this technology would benefit from increased collaboration by NASA with outside organizations. For example, some U.S. research universities are employing high-end computing systems to solve highly complex, multiphysical problems with the support of the National Science Foundation, the Department of Energy’s Office of Science, and other government agencies. Several multi-university collaborations have been established to tackle these advanced modeling and simulation challenges employing advanced algorithms, software, working data storage, and user–machine interfaces. Research into shock wave phenomena and plasma processes is included in the topics under study.

• 4.3.7, Grappling
• 4.4.8, Remote Interaction
• 9.2.7, Terrain-Relative Sensing and Characterization
• 9.2.8, Autonomous Targeting
• 14.3.2, Thermal Protection System Modeling and Simulation

As shown in Chapter 3, technologies 9.2.7, 9.2.8, and 4.3.7 have been included in the list of the highest-priority level 3 technologies.

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⁸ NASA, 2015, NASA Technology Roadmaps: Thermal Management Systems, Washington, D.C., July, http://www.nasa.gov/offices/oct/home/roadmaps/index.html.