National Academies Press: OpenBook

3D Printing in Space (2014)

Chapter: 5 A Possible Way Ahead for the Air Force

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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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5

A Possible Way Ahead for the Air Force

Several Air Force commands have responsibilities for space systems, including the Air Force Space Command (AFSPC), headquartered at Peterson Air Force Base (AFB), and the Air Force Materiel Command, headquartered at Wright-Patterson AFB, both of which sponsored this study. Program management and system acquisition responsibilities for Air Force space systems are the responsibility of the Air Force Space and Missile Systems Center at Los Angeles AFB, which is a part of AFSPC. New developments in manufacturing technology for military space systems are the responsibility of the Materials and Manufacturing Directorate of the Air Force Research Laboratory (AFRL), located at Wright-Paterson AFB. AFRL’s Space Vehicles Directorate, located at Kirkland AFB, engages in the discovery and delivery of technologies for satellite systems.1

Work done at AFRL includes initiatives in additive manufacturing, verification and validation related to manufacturing process simulation, and modeling related to aerospace systems.2 This includes a history of additive manufacturing work with metals, including laser direct manufacturing; additive manufacturing of super alloys; and advanced manufacturing of specific alloys. Most of this work has been focused on aerospace aircraft applications, with only a modest amount of recent work directed toward using additive manufacturing for spacecraft construction or operations. The AFRL Space Vehicles Directorate engages in development of technologies related to spacecraft construction, systems, and operations.

Operational applications of additive manufacturing and associated technologies lie within the purview of the AFSPC and Air Force contractors working on specific launch and space systems, such as global positioning, wide-band global communications, missile warning, space and terrestrial weather, and strategic protected communications.

THE CHALLENGE

The Air Force operates large and varied fleets of satellites. This responsibility now faces significant challenges in a period of constrained federal and Department of Defense (DOD) budgets. In 2011, the commander of AFSPC

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1 C.J. McNutt, R. Vick, H. Whiting, and J. Lyke, “Modular Nanosatellites-Plug-and-Play (PnP) Cubesat,” AIAA 7th Responsive Space Conference 2009, Paper RS7-2009-4003, American Institute of Aeronautics and Astronautics (AIAA), Reston, Va., 2009.

2 Air Force Research Laboratory (AFRL) documents often use “direct digital manufacturing” to mean “digital data to finished part with little human interaction,” rather than the more widely used industry process term, additive manufacturing.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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directed that priority be given to resolving four key challenges, one of which was to “provide a full-spectrum launch capability at dramatically lower cost.”

This relates directly to the present study in that, if future additive manufacturing methods for constructing satellites on the ground and in space prove effective, the masses of satellites will likely be significantly lower than today, and the Air Force might be able to use smaller and less expensive launch vehicles to satisfy its mission needs. The high cost of launch vehicles is currently a major factor facing Space Command, and the Air Force has indicated that the reduction in launch costs is one of its primary incentives for looking into applications of additive manufacturing.3

With respect to valuable technologies for all areas of Air Force responsibility, the Office of the Air Force Chief Scientist issued a report in 2010 of a special study known as “Technology Horizons.” This report provided Air Force and contractor organizations with a vision of science and technology (S&T) developments needed to support Air Force missions in the period 2010-2030.4

Technology Horizons made two pertinent observations with respect to Air Force space responsibilities. The first was that small satellites (i.e., those with mass less than 200 kg) might have useful military capabilities, including imaging, communication links, and scientific data about space weather.5 The second observation was of the value of responsiveness to combatant commanders, aided perhaps by rapidly composable platforms put together with suitable optical, communications, or other systems and launched within several days in response to significant military threats.6

The topic of building spacecraft was raised 2 years later in the 2013 Air Force Global Horizons report.7 This report provides the most recent, fully vetted public statement of expected Air Force challenges and opportunities over the coming three decades. It too was produced under the aegis of the Air Force’s Office of the Chief Scientist, with active participation by numerous senior Air Force leaders, DOD military and civilian experts, and experts from other federal agencies and advisory committees.

Global Horizons spans many topics and includes evaluation of future technological capabilities available to the Air Force for fabricating aircraft and spacecraft using the tools of additive manufacturing. Additive manufacturing is now regarded as a potentially promising means for the Air Force and DOD to reduce the cost of designing and producing parts for air and space systems needed to fulfill Air Force missions. The report also considers the possibility of using additive manufacturing facilities for fabricating entire systems, such as drones and spacecraft. The possibility of on-orbit repair and maintenance using additive manufacturing technologies was also identified as a possible way to reduce the annual maintenance cost of defense satellite systems.

In attempting to address the issue of weight and cost growth, including mission growth, of the current fleet of Air Force satellites, the Global Horizons study reached the following conclusion:

We can revolutionize our space architectures by using hosted payloads and launching smaller, affordable, and fractionated satellites in disaggregated constellations.8

This is a conclusion similar to that delineated in an AFSPC white paper, “Resiliency and Disaggregated Space Architectures.”9 Later, with respect to new technologies, the Global Horizons report concluded the following:

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3 Matt Fetlow, AFRL, presentation to the committee, April 17, 2014.

4 Office of the U.S. Air Force Chief Scientist, Technology Horizons (Final Report): Air Force Global Science and Technology Vision, AF/ST TR 10-01-PR, September 2011; originally released on May 15, 2010, as Report on Technology Horizons: A Vision for Air Force Science & Technology during 2010-2030, Volume 1, AF/ST-TR-10-01-PR, Washington, D.C.

5 Ibid, p. 33. The list of potential uses was considerably expanded in the Air Force’s Global Horizons report, issued in 2013.

6 Ibid, p. 69, see Potential Capability Area 27; p. 98.

7 Office of the U.S. Air Force Chief Scientist, Global Horizons; Air Force Global Science and Technology Vision AF/ST TR 13-01, June 13, 2013.

8 Ibid, p. 12.

9 Air Force Space Command, “Resiliency and Disaggregated Space Architectures,” white paper, released August 21, 2013, http://www.afspc.af.mil/shared/media/document/AFD-130821-034.pdf.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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New technologies such as additive manufacturing in space [enabling on-orbit construction and repair], combined with modular and open architectures, can help realize low-cost satellites, and agile, reconfigurable space systems.10

and suggested the Air Force

  • Redefine space acquisition in accordance with disaggregated satellites and inexpensive launch with a goal of greater than 10X cost reduction employing advanced technologies,
  • Pursue Air Force technologies for space, e.g., adaptive manufacturing in space, . . .
  • Make targeted investments in autonomous/robotic systems and platforms.11

In 2013 the U.S. Air Force Scientific Advisory Board (AFSAB) undertook a study of the value of small satellites (having masses less than 300 kg) to the Air Force mission.12 This topic was motivated by concern about a rapidly changing strategic setting for the Air Force’s space systems. Such changes included evolving threats to U.S. military and intelligence spacecraft, diminishing federal budgets, increases of international space activity, increasing global capabilities for technology miniaturization, and emerging space launch options.

From their work, the AFSAB concluded that smaller satellites might be able to achieve significant defense mission capabilities within the next 2-5 years and serve important, continuing roles in the future. The AFSAB also recommended that the Air Force initiate various S&T investments to enable the far-term employment of smaller satellites. Details of these can be found in the abstract of their study.

There are several important technical opportunities for the Air Force that might contribute to the maintenance of space superiority in coming decades, as enumerated in both the Technical Horizons and Global Horizons reports and the work of the AFSAB. They are as follows:

  • Advanced manufacturing. Advanced manufacturing technologies will enable open architectures that permit rapid prototyping, mission-specific reconfigurability; material tailoring for specific applications; efficient small-lot production; and better systems, faster and cheaper.
  • Redefined qualification and certification paradigm. The qualification and certification paradigm can be redefined to allow rapid utilization of products from advanced manufacturing and additive manufacturing specifically (efficiently from prototype to practice). The new paradigm could eliminate the excessive development times for complex systems by inclusion of concepts such as defined and finite system life, qualification and certification as “adequate” for this application for this length of time, and process qualification and certification vis a vis component qualification and certification.
  • Digital Thread and Digital Twin.13 Digital Thread, comprised of advanced modeling and simulation tools that link materials, design, processing, and manufacturing information, will provide the agility and tailorability needed for rapid development and deployment, while also reducing risk. Digital Twin will be a virtual representation of the system as an integrated system of data, models, and analysis tools applied over the entire life cycle on a tail-number unique and operator-by-name basis. Modeling and simulation tools will optimize manufacturability, inspectability, and sustainability from the outset. Data captured from legacy and future systems will provide the basis for refined models that enable component and system-level prognostics.
  • Autonomous/remotely operated systems. Home-station logistic operations and delivery will be enhanced with the increased use of robotic or remotely operated systems. Deploying the system should reduce the

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10 Ibid, p. 13.

11 Ibid, p. 20.

12 The AFSAB is a federal advisory committee that provides the Secretary of the Air Force and Chief of Staff of the Air Force with independent advice on Air Force science and technology. Such advice is based on annual studies of emerging technologies and their potential value to long-term needs of the Air Force. Air Force Scientific Advisory Board Study, “Microsatellite Mission Applications,” July 2013. Note the definition of “microsatellite” differs from that of the Air Force Office of the Chief Scientist and Table 6.1, which is the nomenclature adopted by this committee.

13 E.H. Glaessgen and D.S. Stargel, “The Digital Twin Paradigm for Future NASA and U.S. Air Force Vehicles,” AIAA 53rd Structures, Structural Dynamics, and Materials Conference, April 26, 2012, AIAA, Reston, Va.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
×
  • forward human footprint. Material processing and handling (armaments and cargo), servicing, maintenance, emergency response, protection, and base surveillance are all potential automation/remote operation targets.

  • On-site production. Advances in manufacturing technology like additive manufacturing would allow rapid generation of needed devices and parts. Use of indigenous resources and assets, including recycled materials, offer flexible and potentially cost-saving procurement options.

THE REALITY OF ADDITIVE MANUFACTURING

The committee understands the breadth and potential importance of broad forms of advanced manufacturing technology, and specifically additive manufacturing, to the Air Force’s needs and responsibilities in space. Yet, additive manufacturing is still an emerging, incomplete, and relatively immature field of manufacturing technology, albeit rapidly evolving in commercial, academic, governmental, and entrepreneurial ground-based laboratories and facilities.

The cutting edge of additive manufacturing-related satellite system production is now at the level of creating and evaluating simple electromechanical systems for ground and space applications in small terrestrial laboratories across the United States and abroad.14,15

With respect to electronics, printing of electric power circuits with additive manufacturing is a viable undertaking, as evidenced by ongoing work over the past decade at the University of Texas, El Paso.16 However, additive manufacturing is regarded as inadequate for printing of advanced digital electronic circuits that are essential for spacecraft. Commercial-quality additive manufacturing machines have minimum feature resolutions on the order of 50 to 100 µm. In contrast, radiation-hardened integrated circuits for space systems have feature sizes on the order of 0.35 µm.17 Other very advanced circuits being considered for spacecraft design and implementation are at feature sizes of 90 nm and smaller. At the present time, the solution is to hand-insert and lock integrated circuits and other high-density digital circuit cards into additive manufacturing-prepared receptacles. In the future, a similar action will likely be the simplest solution for fabrication of spacecraft aboard a space platform, with the insertion being made by a local robot or some type of intelligent machine.

It is clear from these and other examples that many different questions of technology and engineering practice will have to be resolved before additive manufacturing can be embraced as an effective, dependable, cost-reducing, and strategically acceptable means of producing national security spacecraft on the ground, let alone in a human-tended or robotic orbiting facility.

AIR FORCE EXPERIENCE WITH ADDITIVE MANUFACTURING

The Air Force relies on commercial vendors to design, build, test, and transport spacecraft into Earth orbit. Definitive requirements for the desired additive manufacture of spacecraft will have to be developed by the government before competitive contractual bidding can become a reality. Potential contractors will bid based on their understanding of all aspects of spacecraft documentation, construction, testing, evaluation, and operations as well as the contract incentives related to meeting cost, on-time delivery, lifetime on orbit, and other factors. At the present time, aerospace industry knowledge of additive manufacturing, while rapidly advancing, is in its early stages with respect to all aspects of spacecraft production, including physical and environmental properties, engineering and manufacturing, materials, knowledge and specification inserted electronics, and reliability.

The AFRL Materials and Manufacturing Directorate has a significant portfolio of work in additive manufacturing.18 A lead AFRL researcher in additive manufacturing also serves as the Department of Defense manager for America Makes, a network of companies, nonprofit organizations, academic institutions, and government agencies that was founded in August 2012 as the flagship institute for other National Network for Manufacturing

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14 Aguilera et al., 3D Printing of Electro Mechanical Systems, SFF Symposium Proceedings, 2013.

15 K. Short and D. Van Buren, Printable Spacecraft: Flexible Electronic Platforms for NASA Missions, Phase 1 Report, NIAC, September 2012.

16 See http://engineering.utep.edu/announcement111813.htm.

17 See http://www.atmel.com/Images/AERO-4015i-Integrated%20Circuits-Space%20Rad-Hard_US-E-0912_LR.pdf.

18 Mary Kinsella, AFRL, presentation to the committee, April 17, 2014.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
×

Innovation institutes. These institutes were established in response to the strategic guidance from the president to enhance U.S. capabilities and competitiveness in advanced manufacturing. While AFRL additive manufacturing work is extensive, it is, to date, largely aimed at aeronautical/aircraft applications (Figures 5.1 and 5.2). Significant additional research to fully close all the gaps will be required by AFRL to successfully implement additive manufacturing either in space or on the ground for space applications.

Where Is Additive Manufacturing Most Beneficial?

Completely additively manufactured CubeSats are already being contemplated, and somewhat larger additively manufactured platforms could come as funds and capabilities expand. This work is important in that it provides the Air Force with valuable experience and data on additive manufacturing applications for space. However, as satellites tend toward larger and more complex (and operationally useful) designs, at some point, because of the differing size scales and accuracy requirements, the most efficient way to produce an entire spacecraft will involve multiple modes of construction. Some sections of the spacecraft will be most rapidly and effectively produced by additive manufacturing, while others will be most effectively made through extrusion, castings, or other manufacturing processes at another location. The fabrication of the complete satellite will involve assembly of these components at one site.

At the present time, it appears that additive manufacturing might be beneficial to all sizes of spacecraft, but the largest percentage mass and volume reductions will likely accrue to small satellites; that is, those with masses less than about 200 kg.

The Air Force Vision: Fabrication of Spacecraft in Space

The Air Force charged the committee to, among other things, assess the feasibility of additively manufacturing a fully functional spacecraft and to identify S&T gaps needing to be filled to achieve such a goal. While there may be benefits to rapidly manufacturing an entire spacecraft at an orbital fabrication facility, it is not clear to the committee that such an achievement would be either operationally useful and desirable or economically feasible, especially in the short term (5-10 years).

Finding: There is at present a lack of knowledge to credibly determine whether or not development of an Air Force-specific, space-based additive manufacturing production facility would achieve its expected benefit. Given that such a fabrication center would be highly complex and expensive, a detailed system assessment and cost-benefit analysis might be advisable.

Figure 5.3 depicts several of the areas of technology requiring additional research. When envisioning a capability to print an entire functional spacecraft using additive manufacturing technology in an orbiting facility, there are several questions that serve to illuminate this complexity. For example,

  • Is the envisioned facility intended for a one-time use to be discarded after spacecraft production?
  • If it is intended to be a multiuse facility capable of continually producing spacecraft over a period of years, will it produce a single satellite type or several satellite types?
  • Will all of the spacecraft it produces be deployed in generally the same orbital inclination and orbital parameters? If not, what generic orbit would best suit the range of final orbit deployments?
  • Would final deployment require an orbital transfer vehicle to provide relatively rapid deployment, or could a slower orbital-transfer subsystem be built into the final spacecraft (e.g., electric propulsion)?
  • Is the size of the final spacecraft such that it could be produced internally within an additive manufacturing machine, or would it require an additive manufacturing machine that could produce satellites larger than itself?
  • Would the selected technologies perform better in an atmosphere or in a vacuum?
  • As an important, space-based site of Air Force resources, can this facility be adequately defended against destructive actions on the part of other nations or other aggressors?

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
×

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FIGURE 5.1 The Air Force Research Laboratory’s Additive Manufacturing Strategy emphasizes the development of this technology primarily for ground-based use for aircraft. SOURCE: Courtesy of the U.S. Air Force.

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FIGURE 5.2 Currently, the Air Force Research Laboratory (AFRL) is focusing on ground-based and aviation-related additive manufacturing technologies and applications. AFRL has evaluated relatively few space-related applications. SOURCE: Courtesy of the U.S. Air Force.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
×

image

FIGURE 5.3 Areas requiring further research for development of a space-based additive manufacturing production facility.

The answers to these questions would directly influence the type and size of the required additive-manufacturing machine and supporting infrastructure.

Producing an entire functional spacecraft would require a number of different materials to produce the desired component properties and capabilities. This could require multiple writing heads, which would need to be precisely controlled in three dimensions over the entire production volume. There are certain components whose characteristics make producing them with additive manufacturing technologies extremely difficult, if not impractical. Two examples are microelectronics and optics. It is highly unlikely that any reasonable amount of technology investments in additive manufacturing would ever result in a competitive alternative to the current microelectronics lithography capabilities. Similarly, the precise accuracies required in optics would be difficult to replicate with additive manufacturing processes. As an example, a star sensor is a basic component of most satellites and is relatively unsophisticated compared to many other satellite subsystems. Yet, it would be extremely difficult to manufacture all of the components of a precision star sensor using additive manufacturing on the ground, let alone in orbit. Additive manufacturing will not replace microelectronics fabrication, but the committee believes that it does not have to. Additive manufacturing can print the structure and the electronic and other components required for functionality, manufactured by other means, can be embedded as described in earlier sections of this report.

Once the additive manufacturing system’s details have been worked out, the support services and utilities required to establish a functional production facility would need to be addressed. Again important questions would need to be resolved. For instance,

  • What structure would be required to support the machine and all its required support functions?
  • How much power would the facility require in both its operating and dormant modes?
  • How would raw materials be attached, stored, repositioned, mounted onto the additive manufacturing machine, and removed after use?
Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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  • How would the resupplied raw materials be brought into proximity to the production facility and attached?
  • What type of attitude control and vibration control would the facility require to support the additive manufacturing machine?
  • How do the construction machines test, detect, and repair errors in the fabricated items they produce?
  • Would the facility need a propulsion capability to maintain its orbit?
  • Would the production facility be able to function entirely autonomously, or would it require continual human tending? If so, would this human tending require an associated habitat to support the crew? Could it be human tended only during production runs? Could it be run autonomously and only require periodic human maintenance?

Finally, with all these technical and operational questions answered, the Air Force might be in a position to determine if the system would provide sufficient economic advantages to merit deployment and, more importantly, if it would provide sufficient new military capabilities or operational advantages to merit its cost. If the answers to all of these questions were judged to be affirmative, it would still need to be determined if the system would bring with it military vulnerabilities that could be effectively be overcome. Such a production facility would be vulnerable to both natural and adversarial hazards as it continually orbited Earth.

Recommendation: As the technology evolves and as projects utilizing this technology are considered, the Air Force should conduct a systems-analytical study of the operational utility of spacecraft and spacecraft components produced in space using additive manufacturing compared to other existing production methods.

A WAY AHEAD FOR THE AIR FORCE

Additive manufacturing is a technology that has great potential to significantly reduce payload mass and size of national security spacecraft and, thereby, achieve a lower unit cost per spacecraft. However, this technology is in its infancy and, as yet, has not achieved sufficient technological maturity to be an immediate alternative to traditional fabrication of national security spacecraft.

The discussion presented here provides a path for the Air Force to begin to answer some of the fundamental questions of economic and operational benefit.

Some In-Space Specific Technical Challenges

Should the Air Force ultimately decide to pursue additive manufacturing in space, there are unique technical challenges that will have to be overcome. In this context, the assertion that bringing raw materials to space could significantly reduce overall costs of putting a new spacecraft into use is only a small part of the overall operating expenses of such a facility.

Additive manufacturing by itself is a relatively slow, energy-intensive construction process. Assembling a spacecraft on the ground would likely be faster, and the fastest approach may well be rapid construction in a ground facility, followed by a rapid launch from a “smaller” launch vehicle requiring a minimum of integration effort. Determining how to avoid long satellite construction time is essential before committing to construction of an in-space additive manufacturing system. (This argument is also true for an additive manufacturing repair platform.)

The designs and equipment fabrication for Air Force missions are done with careful attention to materials selection and mechanical, electrical, and thermal standards to enable the equipment to survive the strong forces and rapidly changing thermal environment of the launch vehicle. Once in space, the diverse array of space equipment will be exposed to a complex mix of environmental conditions, including the near-vacuum of space, the strong, orbitally varying heating effects of sunlight, possible electrostatic charging, deleterious effects of strong solar ultraviolet radiation on the equipment container’s thermal protection and surface materials, reduction of efficiency of solar electric cells resulting from solar radiation and highly variable energetic particle fluxes, and the damage that occasionally arises from micro-meteorites.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
×

Equipment sent into space as a free-flying platform is designed as a self-consistent, operational entity with many different systems and subsystems cooperatively working in synchronism to achieve the goals of its architects. There is a vast range of specialized materials and topological complexity in such objects, including both the components of the satellite system operations and the highly complex and often extraordinarily miniaturized components of scientific instruments. In addition, scientific instruments sent into space have to be carefully calibrated and operationally tested in special ways prior to launch, often precluding any easy way to recalibrate such instruments while in space.

This is not to say that a major investment in space-based additive manufacturing should not be made. Rather, it is clear that additive manufacturing offers niche advantages to space systems, both for ground-based engineering and space-based operations. But a long-term, strategic plan of engineering system and operation planning investments is essential to take advantage of this new manufacturing technology in the environment of space. These should include many different efforts to build space-qualified parts and subsystems via additive manufacturing prototyping and even final flight-worthy components.

Finding: An independent, free-flying additive manufacturing satellite construction platform, human-tended or robotic, will require extensive ground-based development in additive manufacturing, robotics, and telepresence. Given the various limitations of power, cost, long build times, verification of manufacture, and other factors discussed previously, a large number of issues require resolution before committing to such a program.

ADDITIVE MANUFACTURING FOR SPACE

It appears to the committee that the ability to develop a space-based additive manufacturing capability able to produce fully functional, operational Air Force satellites in orbit anytime in the reasonable future is well beyond the current state of the art or, for that matter, any current technology plans. There are, however, several key technology areas that are unlikely to be pursued by either commercial industry or NASA that the Air Force could reasonably fund that would contribute to a better understanding of the eventual feasibility of such a capability. Some examples of these are discussed in Chapter 3. They include robotics in zero gravity and materials processing in zero gravity and in a vacuum. Additionally, there are a number of activities that should be pursued to qualify additive manufactured materials for application in the space environment. The detailed characterization of all these materials and their properties over time in the environments they would be exposed to in space need to be well understood. This is important not only for their considered use in operational systems, but also to understand what, if any, potential vulnerabilities they might introduce into operational systems.

At the moment, the economic drivers for investigating some of the issues discussed above (the in situ manufacturing of small, complex electronic and optical parts, as well as motors) are minimal; there is not strong “push” in these areas to include these types of specialized components in additive manufacturing studies.

Recommendation: The Air Force should continue to invest in additive manufacturing technologies, with a specific focus on their applicability to existing and new space applications, and invest in selected flight experiments.

The committee believes it to be very important for the Air Force technology communities to stay acutely aware of all the activity and progress in the additive manufacturing area and its potential for space applications; without this level of currency, the Air Force will not be able to be an effective and knowledgeable consumer of this potentially important capability.

Recommendation: The Air Force should consider additional investments in the education and training of both materials scientists with specific expertise in additive manufacturing and spacecraft designers and engineers with deep knowledge of the use and development of additively manufactured systems.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Further, in the near term, the Air Force should not lose sight of the opportunities to apply additive manufacturing capabilities to existing or pending space systems. The introduction of materials and components produced with additive manufacturing techniques could reduce the cost, lead-time, weight, or other important factors.

As described above, the challenges of manufacturing of entire spacecraft in space are daunting, and the benefits are unclear. The technology challenges enumerated in Chapter 3 would form the basis for a long-term technology investment plan. However, the benefit of additive manufacturing in ground-based production is a far more demonstrated fact. In addition, there may be cases in the near- or midterm future where the space-based manufacture of less complex components and subsystems for spacecraft, or space-based assembly, may have operational and economic benefit (for example, in the construction of large antenna apertures, which have related challenges such as maintaining precise attitude pointing, establishing surface precision, and ensuring structural stability). If the Air Force can consider and take advantage of opportunities to incorporate additive manufacturing, then technical, acquisition, and contracting policies can provide incentives to Air Force contractors for performing the necessary research and to incorporate additively manufactured parts in space and launch systems. The committee cannot perform this task for the Air Force because the military has to develop its own requirements and bring together the interested parties that will implement a research strategy.

Recommendation: The Air Force should establish a roadmap with short- and longer-term goals for evaluating the possible advantages of additive manufacturing in space. The Air Force should build on the considerable experience gained from other Air Force technology development roadmaps. The space-based additive manufacturing roadmap should include, but not be limited to the following:

  • Developing goals for using the technology in key Air Force missions, especially for autonomously or minimally attended, space-based additive manufacturing and free-flyer missions;
  • Identifying flight opportunities, including those on non-Air Force platforms such as on the International Space Station during its next decade of operations;
  • Targeting the full technology-development life-cycle and insertion strategies through 2050, aligned with Air Force missions, and related collaborations.

NASA is currently the leader in the development of space-based additive manufacturing technology and also operates a valuable research platform, the International Space Station (ISS). The ISS offers both internal and external research locations. For example, it may be possible to mount an additive manufacturing machine, such as a machine for producing large truss or antenna structures, to an external location on the ISS and operate it in the vacuum environment while enabling close monitoring and later inspection of parts. DOD has a history of ISS research, typically participating through the Air Force’s Space Test Program. The Air Force can maximize its return on investment by seeking cooperative opportunities with NASA whenever possible.

Recommendation: The Air Force should make every effort to cooperate with NASA on in-space additive manufacturing technology development, including conducting research on the International Space Station.

Recommendation: NASA and the Air Force should jointly cooperate, possibly involving additional parties including other government agencies as well as industry, to research, identify, develop, and gain consensus on standard qualification and certification methodologies for different applications. This cooperation can be undertaken within the framework of a public/private partnership such as America Makes.

Cooperation can take many forms. The Air Force and NASA could jointly share the costs of research and development, or merely share data. But the opportunities available are greater now than they have been in even the recent past.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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CONCLUSION

Additive manufacturing technology is developing rapidly, so rapidly that it is difficult to determine its applications just a few years in the future. However, the committee concluded that the Air Force has been paying less attention to this developing technology for space use than it should, and it may be missing opportunities to leverage the work that is being conducted by NASA. By starting efforts to consider where additive manufacturing technology can possibly fit into its existing missions, and where it might have positive benefits for things such as reducing launch costs, the Air Force may identify unique value and encourage those actively involved in this technology development to propose new solutions to the Air Force’s space requirements.

Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Suggested Citation:"5 A Possible Way Ahead for the Air Force." National Research Council. 2014. 3D Printing in Space. Washington, DC: The National Academies Press. doi: 10.17226/18871.
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Additive manufacturing has the potential to positively affect human spaceflight operations by enabling the in-orbit manufacture of replacement parts and tools, which could reduce existing logistics requirements for the International Space Station and future long-duration human space missions. The benefits of in-space additive manufacturing for robotic spacecraft are far less clear, although this rapidly advancing technology can also potentially enable space-based construction of large structures and, perhaps someday, substantially in the future, entire spacecraft. Additive manufacturing can also help to reimagine a new space architecture that is not constrained by the design and manufacturing confines of gravity, current manufacturing processes, and launch-related structural stresses.

The specific benefits and potential scope of additive manufacturing remain undetermined. The realities of what can be accomplished today, using this technology on the ground, demonstrate the substantial gaps between the vision for additive manufacturing in space and the limitations of the technology and the progress that has to be made to develop it for space use.

3D Printing in Space evaluates the prospects of in-space additive manufacturing. This report examines the various technologies available and currently in development, and considers the possible impacts for crewed space operations and robotic spacecraft operations. Ground-based additive manufacturing is being rapidly developed by industry, and 3D Printing in Space discusses government-industry investments in technology development. According to this report, the International Space Station provides an excellent opportunity for both civilian and military research on additive manufacturing technology. Additive manufacturing presents potential opportunities, both as a tool in a broad toolkit of options for space-based activities and as a potential paradigm-changing approach to designing hardware for in-space activities. This report makes recommendations for future research, suggests objectives for an additive manufacturing roadmap, and envisions opportunities for cooperation and joint development.

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