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 (ISS) 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, and there has been a substantial degree of exaggeration, even hype, about its capabilities in the short term. The public often believes that these technologies are further along than they actually are. 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. What can be accomplished in the far future depends on many factors, including decisions made today by NASA and the Air Force.1
When looking at the potential values of in-space additive manufacturing, the Committee on Space-Based Additive Manufacturing found that ground-based additive manufacturing for aerospace systems has more immediate and long-term impacts to reduce cost and increase performance of space systems, as well as establish the technical basis of later, space-based additive manufacturing. The committee also determined that additive manufacturing in and of itself is not a solution, but 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.
THE ORIGINS OF THIS STUDY
The concept of space-based manufacturing in general has existed almost since the beginning of the space age but has made limited progress because of the difficulties of space-based construction. However, additive manu-
1 Although there are other government space actors, including the National Oceanic and Atmospheric Administration, the Navy, the National Reconnaissance Office, and so on, this study was commissioned by the Air Force and NASA and therefore focuses on their missions.
facturing, often referred to as “3D printing,” has captured the public imagination in recent years and received considerable media attention. The technology is interesting and exciting, it can provide benefits over conventional manufacturing processes, and has become publicly accessible in recent years, with small desktop devices entering the market for home use. Many of the claims made in the popular press about this technology have been exaggerated, and it appears that even as it continues to advance and evolve, additive manufacturing will primarily supplement rather than replace many existing manufacturing methods.
Two sectors in particular, biomedical and aerospace, are the largest users of the technology. Additive manufacturing has potential for aerospace use to reduce costs, shorten production schedules, and enable the development of new structures. Many companies large and small are evaluating the ability of ground-based additive manufacturing to produce components for aircraft and spacecraft, and additively manufactured parts have already flown in space.
The Air Force Space Command, the Air Force Research Laboratory, and NASA’s Space Technology Mission Directorate charged the National Research Council with evaluating the prospects of in-space additive manufacturing. After examining the various technologies available and in development and hearing from a wide range of experts on the subject, the committee concluded that in-space additive manufacturing is likely to have a significant impact on crewed space operations. Its potential for robotic spacecraft operations is less clear, especially in the short term. Because some of the most obvious applications are for human spaceflight, the government cannot expect private industry to sponsor space-based additive manufacturing on its own. Ground-based additive manufacturing is being rapidly developed by industry, and the committee therefore sought to determine what aspects of space-based additive manufacturing industry would not undertake on its own. The two most obvious are space-based robotics and automation and hybrid manufacturing in which two or more manufacturing processes work together, preferably in an automated way, in the space environment. Because the most obvious applications are for human spaceflight and exploration and for military missions, the government cannot expect industry to invest in technology developments that do not have a clear path to profit. The committee also determined that the ISS provides an excellent opportunity for both civilian and military research on additive manufacturing technology.
As recently as the 1990s, NASA and the Air Force as well as other military organizations, such as the Defense Advanced Research Projects Agency, conducted cooperative research with each other with substantial results. The committee believes that in-space additive manufacturing is an area where such civil-military cooperation can and should occur.
THE PROMISE AND POTENTIAL OF SPACE-BASED ADDITIVE MANUFACTURING
Additive manufacturing as a commercial technology that builds three-dimensional parts directly from computer files has existed since the 1980s and has been evaluated for space-based use since the late 1990s. In its most basic form, additive manufacturing involves the process of adding material on top of some kind of build platform and building on it consecutively until an object is produced. This is opposed to more conventional subtractive manufacturing methods. Currently, most additive manufacturing techniques involve the use of only a single material and thus require that functional parts consisting of more than one material be developed by separate machines and undergo finishing and assembly.
The application of additive manufacturing to the space environment could likely lead to a change in our ideas and concepts of what satellites look like, how they are designed, and what they can do. Additive manufacturing is not just a different way to manufacture components and space-based devices, but rather offers a new way to reconceptualize space architectures. It enables development of structures entirely unlike those needed in the high-gravity environment of Earth or to survive the rigors of space launch. Large structures may be useful in space for many applications, from antennas to structural supports (although it is worth noting that most additive manufacturing machines today make parts smaller than themselves, so this is a different approach to the technology). Additive manufacturing can potentially lead to the construction of smaller, more reliable, less massive satellite systems or their key components (including support structure, power distribution system, solar arrays, instruments, outer protective shell, etc.), which could reduce launch requirements and costs.
The lack of gravity and atmosphere presents possibilities for additive manufacturing in space not available to ground-based machines. The absence of gravity might permit a printer to work on the “bottom” and the “top” of an
object at the same time. Imagine a printer for use in space that has multiple print heads and works on all six sides of an object resting in the space between the heads. Air jets or electrostatic attraction might be used to keep the growing object in place, or even to move it to the orientation most suitable for printing. For additive manufacturing in space, considering a 20-year time horizon, NASA has a unique opportunity to encourage innovative thinking about how to capitalize on the lack of gravity or the lack of atmosphere in space to better and more rapidly form objects that are similar to those made on Earth.
Although additive manufacturing is advancing rapidly and is increasingly used on the ground for an expanding number of industrial purposes, the basic technology is still relatively young. There are some fundamental issues that industry will have to resolve before space-based applications can be derived. A clear understanding of the relationships between the material and structural properties and their dependence on processing techniques needs to be established to ensure consistency in production. The production process could also benefit from standardization of design software, file formats, and processing and equipment parameters, including developing closed-loop feedback control systems for the machines themselves. Most importantly, a verification and certification methodology will have to be defined that guarantees the quality of the additively manufactured parts.
Aerospace systems have critical missions and must meet rigorous standards for quality and reliability—standards that are set to ensure mission success. In order to benefit from additive manufacturing approaches, the manufacturing community—with government involvement—will have to address the issues of qualification and certification. A standard approach to qualification and certification of finished parts will simplify the application of additive manufacturing to the space environment and also enable more widespread application on Earth. This led the committee to its first recommendation.
Recommendation: NASA and the Air Force should jointly cooperate—and possibly involve 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.2
THE CHALLENGES OF SPACE-BASED ADDITIVE MANUFACTURING
Production of additive manufacturing components on the ground currently requires extensive human presence and participation. This is not always due to the complexity of the manufacturing operation; sometimes human labor to move parts from one machine to the next is cheaper than an automated system. Some automated manufacturing capabilities on the ground are currently under development, although it is not clear that a completely automated part-handling sequence of operations (e.g., setup, build, removal, finishing) is under development that would eliminate the need for human presence. Significant further development will be required for automated space-based additive manufacturing, and much of this development is likely to require government support. Spacecraft manufacturing is a conservative field, and private companies are reluctant to introduce advanced technologies on their own initiative. For this reason, government plays a vital role in conducting research that can ultimately benefit civil, military, and commercial satellite manufacturers.
Continuing development of terrestrial additive manufacturing processes will not necessarily drive investment or development of automation and human operator capabilities that might be translatable for space applications. Transplanting an additive manufacturing capability to space requires consideration of how the supporting infrastructure, including the applicability or desirability of maintaining humans in the loop, needs to be evolved to operate in the new environment. At the present time, the ISS offers an excellent research platform for additive manufacturing work. The ISS has the benefit of already being paid for. But the ISS will not exist forever, and in future decades, space-based additive manufacturing will require its own infrastructure support, with its own costs.
There are numerous potential benefits to using this technology in space. Additive manufacturing may provide
2 America Makes is the current government-led consortium addressing additive manufacturing issues. NASA and AFRL both support America Makes.
entirely new capabilities. Both NASA and the Air Force have begun evaluations of small satellites, such as CubeSats, and NASA in particular is researching the role of space-based additive manufacturing for such satellites. NASA is currently evaluating the feasibility of this approach. The committee concluded that further evaluation of the costs and benefits of approaches to additive manufacturing in space should be conducted. In some cases, it may be possible to reduce costs by eliminating the requirement to launch spare or replacement parts into orbit.
Recommendation: As the technology evolves and when projects utilizing this technology are considered, NASA and the Air Force should jointly undertake a cost-benefit analysis of the role of space-based additive manufacturing in the construction of smaller, more reliable, less massive satellite systems or their key components.
By making baseline assumptions about scope and reference points, NASA and the Air Force can begin to define the overall parameters for additive manufacturing and its impact on spacecraft development. Such analysis, although limited in scope, can help to guide future decision making regarding research expenditures.
The infrastructure costs will have to be taken into account when evaluating the future potential of additive manufacturing in space, leading the committee to another recommendation:
Recommendation: When considering moving additive manufacturing technology to the space environment, any person or organization developing plans should include in their planning the infrastructure required to enable fabrication processes based on additive-manufacturing, such as power, robotics, and even human presence. Studies examining the types of infrastructure should be undertaken in tandem with the development of the additive manufacturing technology itself.
However, the committee was struck by the fact that additive manufacturing may also provide totally new capabilities. Thus, it would be a mistake to make additive manufacturing decisions based entirely upon cost-benefit determinations of existing products and functionalities, because doing so might lead to missing valuable opportunities to advance capabilities with this new technology.
Recommendation: Actual costs of the reproduction of components or spacecraft should not be the sole criterion for evaluation of the benefits of additive manufacturing; criteria should also include the value of creating structures and functionalities not feasible before.
NASA AND ADDITIVE MANUFACTURING
Currently, NASA is the leader in space-based additive manufacturing. After first evaluating the technology in the late 1990s, the agency has sponsored an upcoming experiment aboard the ISS involving a small “3D printer” that will manufacture plastic parts that will be evaluated for quality and may be useful for operations. Many NASA field centers are currently conducting experiments with additive manufacturing on the ground, but only Marshall Space Flight Center is actively sponsoring space-based applications.
Recommendation: NASA 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.
The committee believes that this broad-based experimentation throughout the agency is valuable. However, it concludes that NASA will benefit from coordination of its many and diverse additive manufacturing activities. NASA’s full use and application of additive manufacturing technologies, both in space and on the ground, could be made more efficient and effective with a stronger associative link between additive manufacturing technology and facility developers and users who may benefit in areas of efficiency, complexity, and cost reductions.
There are many impressive development efforts under way at companies and government-supported laboratories across the country, and NASA has already sponsored communications between interested groups in this area. Although much of this work is proprietary, it will be beneficial for NASA to learn about these developments and to encourage partnerships and sharing of ideas, leading the committee to the following recommendation:
Recommendation: NASA should sponsor a space-based additive manufacturing workshop to bring together current experts in the field to share ideas and identify possible research projects in the short term (1-5 years) and medium term (5-10 years).
NASA recently extended the lifetime of the ISS to 2024. The space station’s lifetime could possibly be further extended. Nevertheless, this represents a finite opportunity for further development of the technology in an ideal environment, when human assistance is possible.
Recommendation: NASA should quickly identify additive manufacturing experiments for all areas of International Space Station (ISS) utilization planning and identify any additive manufacturing experiments that it can develop and test aboard the ISS during its remaining 10 years of service and determine if they are worthy of flight. NASA currently has methods for providing research grant funding for basic research on additive manufacturing. The agency should closely evaluate funded research options to determine which would allow the most rapid transition of additive manufacturing to the ISS.
Because of its broad-reaching activities involving additive manufacturing, NASA could consider creating an enduring forum devoted to additive manufacturing engineering technologies, focusing on serving all NASA centers, universities, small companies, and other organizations. Such a forum could function as a focusing element to orient the agency’s efforts and activities in space-based and terrestrial additive manufacturing, providing a phased capability to identify, facilitate, integrate, and maximize attention and resources to this difficult, long-term objective of developing this technology for space use.
The committee also concluded that NASA needs to formally develop its plans for space-based additive manufacturing. Although the agency seems to be on a reasonable development path for this new but rapidly advancing technology, it is time for NASA to produce an agency-wide roadmap for space-based additive manufacturing.
Recommendation: NASA should convene an agency-wide space-based additive manufacturing working group to define and validate an agency-level roadmap, with short- and longer-term goals for evaluating the possible advantages of additive manufacturing in space, and with implications for terrestrial additive manufacturing as well. The roadmap should take into consideration efficiencies in cost and risk management. NASA should build on the considerable experience gained from its Space Technology Roadmaps. The space-based additive manufacturing roadmap objectives should include, but not be limited to the following:
- Developing goals for using the technology to assist the agency in meeting its key missions, covering all appropriate mission directorates, especially long-duration human spaceflight and planetary operations, which would require defining, understanding, evaluating, and prioritizing the direct and supporting technologies for autonomously or minimally attended space-based additive manufacturing, and robotic precursor and free-flyer missions;
- Identifying flight opportunities, 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 target agency missions, for all appropriate mission directorates, and related collaborations; and
- Ensuring that support for incremental advances to address the technical challenges is supplemented with support for activities related to reaching the full potential of additive manufacturing.
Although 2050 is a long way into the future, NASA has recently announced long-range plans out to the mid-2030s, and the committee believes that technology development horizons should extend beyond current plans. Whatever date NASA decides on, it should be ambitious.
There is naturally some tension between the unfettered creativity and innovation inherent in new technologies and efforts to develop research plans and consensus built roadmaps, which may limit or discourage innovation. The committee believes that NASA is cognizant of this tension and can establish goals while still encouraging innovation. The previously mentioned workshop and forum are ways to accomplish this.
NASA plans to begin conducting experiments using a plastics-based 3D printer aboard the ISS starting in late 2014. In addition to further developing this technology, the next major steps will involve additive manufacturing using metals, which NASA is already evaluating and which the European Space Agency has also indicated it is researching. This technology poses many challenges for space use, including high power requirements. In addition, ground-based technology (such as the use of metal powders) may not be applicable to a microgravity environment. Nevertheless, this is an important technology, and developing a roadmap will help NASA clarify potential research paths.
NASA has ties with other agencies, including foreign partners on the ISS, and these contacts can provide benefits for further development of this technology.
Recommendation: NASA should seek opportunities for cooperation and joint development with other organizations interested in space-based additive manufacturing, including the Air Force, the European Space Agency, the Japanese Space Agency, other foreign partners, and commercial firms.
To prevent duplication of effort, the government-led consortium America Makes can serve a clearinghouse role by creating an additive manufacturing in space working group that includes participation from government, industry, academia, and international partners. Both NASA and the Air Force could be active leaders within the working group and ensure that each builds on the knowledge of the broader additive manufacturing community.
THE AIR FORCE AND ADDITIVE MANUFACTURING
The committee found NASA’s requirement for space-based additive manufacturing to be more clearly defined than the Air Force’s requirements. The committee was informed that the Air Force’s most pressing requirement is to reduce the cost of launching payloads to orbit. At the present time, it is too early to be certain that space-based additive manufacturing will make it possible to reduce the cost of space launch. It is also too early to determine how the Air Force may best make use of this technology, although its potential for the deployment of structures too large or fragile to fit in current launch vehicle payload shrouds could prove attractive for some national security missions.
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 is advisable.
Recommendation: 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.
Considering that the present state of manufacturing focuses on new types of individual components of specialized shapes, composition, and materials, it is clear that the task of manufacturing a complete scientific or military satellite of the complexity of current spacecraft is far in the future, if not impossible. This situation is unlikely to
change unless major, very-long-term changes are made in this nation’s space systems design, engineering methodologies, and infrastructure at all levels.
An independent, free-flying additive manufacturing satellite construction platform, human-tended or robotic, would 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.
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 Department of Defense is already evaluating additive manufacturing technologies for a broad range of ground-based uses, including maintenance centers on Navy ships, Army field-based repair equipment, and design, fabrication, and repair of Air Force aircraft. This technology is sufficiently unique that it requires new skills and training, particularly for aerospace use.
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.
During its information gathering, the committee heard of relatively little Air Force involvement in planning for or developing additive manufacturing for space use. The committee concluded that the Air Force needs to start defining its requirements and research strategy for this technology in order to take advantage of and steer developments for its application to military space missions. The Air Force has well-developed and proven mechanisms for research planning.
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 the International Space Station, during its next decade of operations; and
- Targeting the full technology-development life-cycle and insertion strategies through 2050, aligned with Air Force missions, and related collaborations.
Although the Air Force’s path forward is not clear, the military can capitalize on the fact that NASA has already developed some of the infrastructure that will make it easier for the Air Force to research the potential capabilities of space-based additive manufacturing and is already engaged in current research of its own.3 This provides an opportunity for the Air Force that it would not otherwise have.
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.
3 The committee sought, but was unable to find, historical data on U.S. government funding of additive manufacturing by various agencies.
If additive manufacturing in space does become commonplace, it could increase the debris generated in orbit. Both NASA and the Air Force are well aware of debris hazards and will undoubtedly include such considerations in their efforts.
ORGANIZATION OF THIS REPORT
Chapter 1 introduces additive manufacturing and includes the committee’s statement of task. Chapter 2 discusses potential uses and applications of additive manufacturing in space. Chapter 3 addresses the many technical and manufacturing issues that must be addressed, both terrestrially and extra-terrestrially, before creating and utilizing additive manufacturing in a space environment. Finally, Chapters 4 and 5 outline the next steps for NASA and the Air Force.