It has been an emblematic technology of the “Star Trek” television series for decades: a device that could manipulate matter and energy in such a way that it could create almost every object imaginable, from Captain Picard’s favorite beverage, to various machine parts of the Enterprise. If you’re inclined to view this kind of imaginary technology as being nothing more than an outlandish fantasy, well think again. The advent of additive manufacturing in recent years promises to bring this science fiction vision closer to reality, while revolutionising the entire manufacturing industry along the way.
Developed during the mid-1980s at the Massachusetts Institute of Technology, additive manufacturing, also known as 3-D printing, is a term comprising the set of technologies by which solid 3-dimensional materials can be constructed from a digital computer model. Contrary to the conventional subtractive manufacturing methods that are used today, where objects are fabricated through the subtraction of undesired parts from different types of raw materials in order to produce the desired finished product, additive manufacturing creates objects through the successive layering of raw materials that are laid down on top of each other. The advantages of this could greatly affect economies of scale. By using only the material needed for the creation of an object, 3-D printing produces almost none of the waste byproducts of traditional manufacturing processes. In addition, this technology can combine different raw materials together in ways that aren’t possible in traditional manufacturing, resulting in lighter and cheaper objects whose properties like strength and temperature resistance can be highly customised according to their intended use. And since 3-D printing is essentially the creation of objects from Computer-Aided Design digital files, it can greatly reduce construction and shipping costs by eliminating the need for the expensive and time-consuming production and assembly lines of traditional manufacturing.
3-D printing is already being utilised today, within the automotive, jewelry, food, and electronics industries, among others. Yet one of the biggest beneficiaries of this technology could be the aerospace sector, with many corporations like General Electric and EADS starting to take notice of the potential of this revolutionising technology. But one of the leading backers in 3-D manufacturing is NASA, with the space agency being part of America Makes, a National Manufacturing Initiative which aims to accelerate the development and integration of additive manufacturing technologies in the entire U.S. manufacturing industry. To that end, the agency’s Space Technology Mission Directorate is currently running several research programs in cooperation with private space companies, examining the benefits and potential applications of 3D printing technologies that could revolutionise the space industry. The first promising results of NASA’s efforts came last year during a series of various hot-tests of 3-D printed rocket engine injectors at the space agency’s facilities.
Injectors comprise one of the most critical parts of rocket propulsion systems, mixing together the propellants (oxidizer and fuel) that provide the rocket’s necessary thrust. In addition to having a complex design, their construction (as is the case with every other rocket engine parts) is an expensive and time-consuming process which drives up the overall costs of rocket manufacturing. “Rocket engine components are complex machined pieces that require significant labor and time to produce,” says Tyler Hickman, an aerospace engineer at NASA’s Glenn Research Center in Cleveland, Ohio. “The injector is one of the most expensive components of an engine.” A set of rocket engine injectors built by Aerojet Rocketdyne through additive manufacturing were put through a series of hot-fire tests at the Glenn Research Center in July 2013, successfully demonstrating that they could operate as well as similar, more expensive systems built with traditional manufacturing techniques.
In addition, the 3-D printed components required less than four months to be completed, compared to the almost one year needed for their conventional counterparts, while also being approximately 70 percent cheaper. “Hot-fire-testing the injector as part of a rocket engine, is a significant accomplishment in maturing additive manufacturing for use in rocket engines,” says Carol Tolbert, manager of the Manufacturing Innovation project for the Office of the Chief Technologist at NASA’ Glenn Research Center. “These successful tests let us know that we are ready to move on to demonstrate the feasibility of developing full-size, additively manufactured parts.” In these times of tightly constrained budgets, additive manufacturing could help NASA lower the production costs of space hardware in a way that was previously unimaginable, leading to more affordable space exploration programs for the agency. “NASA recognizes that on Earth and potentially in space, additive manufacturing can be game-changing for new mission opportunities, significantly reducing production time and cost by ‘printing’ tools, engine parts or even entire spacecraft,” says Dr. Michael Gazarik, Associate Administrator of the Space Technology Mission Directorate in Washington, DC. “3-D manufacturing offers opportunities to optimize the fit, form and delivery systems of materials that will enable our space missions, while directly benefiting American businesses here on Earth.”
One of the space agency’s programs that could also benefit from the application of additive manufacturing processes is the Space Launch System, or SLS, which is NASA’s next generation heavy-lift vehicle for transporting astronauts to destinations beyond low-Earth orbit. This became more evident during a round of hot-fire tests of a 3-D printed rocket injector at the agency’s Marshall Space Flight Center in Huntsville, Ala., in August of last year. Although the size of the injector tested was relatively small in size, its design was similar to the roughly 10.5-inch diameter main injector used by the RS-25 engine, which will power the SLS’s core stage. The results showed that the injector was capable of producing a record 20,000 pounds of thrust, for a 3D printed component. “Early data from the test conducted at pressures up to 1,400 pounds per square inch absolute and at almost 6,000 degrees Fahrenheit — typical of the environments experienced by rocket engines — indicates the injector worked flawlessly,” stated NASA following the successful completion of the test. “During the hot-fire test, liquid oxygen and gaseous hydrogen flowed through the injector into a combustion chamber producing 10 times more thrust than any injector ever fabricated using a process known as additive manufacturing, or 3-D printing.”
More importantly, the technologies that were used for its construction were able to make it in two parts, while earlier injectors fabricated with traditional machining processes were comprised by no less than 115 parts. This reduction in the parts needed for the successful operation of rocket engine components, could also drive down the SLS’s construction costs dramatically, while allowing for more efficient and flexible designs of its propulsion system. “This successful test of a 3D-printed rocket injector, brings NASA significantly closer to proving this innovative technology can be used to reduce the cost of flight hardware,” says Chris Singer, Director of Marshall Space Flight Center’s Engineering Directorate. In addition to costing more than half the price of traditionally fabricated injectors, the construction time for the 3-D printed components was similarly reduced from months to weeks. “The additive manufacturing process has the potential to reduce the time and cost associated with making complex parts by an order of magnitude,” adds Singer.
Marshall Space Flight Center’s 3-D printing needs have advanced the additive manufacturing industry in many ways, including ever larger printing capabilities. Just a few years ago, the maximum diameter of any additive manufactured part was 24 inches. Marshall’s needs pushed that to 38 inches. But even that isn’t big enough; according to Nick Case, a Marshall propulsion engineer, to print an F-1 injector, a “printer” of at least 44 inches is needed. According to Mr. Case, Marshall has also used 3-D printing to build custom tools it needs, such as a special wrench needed for disassembling a part from an existing rocket engine currently undergoing testing.
The research conducted by NASA could also prove valuable for the development of rocket engine designs by private space companies as well, since the space agency has made the hot-fire test results available to every U.S. company, through Marshall’s Materials and Processes Information System database. “This entire effort helped us learn what it takes to build larger 3-D parts – from design, to manufacturing, to testing,” says Greg Barnett, an engineer for the project at Marshall Space Flight Center’s Propulsion Systems Department. “This technology can be applied to any of SLS’s engines, or to rocket components being built by private industry.”
Rocket engine designs isn’t NASA’s only area of study when it comes to 3-D printing applications in space. The space agency awarded a $125,000 contract last year to Systems and Materials Research Corporation, based in Austin, Texas, to study the feasibility of constructing a 3-D printer to be used as food synthesizer for use in deep-space missions. NASA hopes that this technology could potentially allow astronauts to “print” their own food during long-duration missions, thus helping to reduce the overall amount of cargo launched from Earth. “As NASA ventures farther into space, whether redirecting an asteroid or sending astronauts to Mars, the agency will need to make improvements in life support systems, including how to feed the crew during those long deep space missions,” states the space agency. “NASA’s Advanced Food Technology program is interested in developing methods that will provide food to meet safety, acceptability, variety, and nutritional stability requirements for long exploration missions, while using the least amount of spacecraft resources and crew time … Additive manufacturing offers opportunities to get the best fit, form and delivery systems of materials for deep space travel. This is why NASA is a leading partner in the President’s National Network for Manufacturing Innovation and the Advanced Manufacturing Initiative.”
As fascinating as this ground-work is, 3-D printing is getting ready to go to the next level, by being launched to the final frontier later this year. Onboard the next commercial resupply mission to the International Space Station by Space Exploration Technologies Corporation, or SpaceX, currently scheduled for launch in August 2014, will be the first 3-D printer to be tested in space. A partnership between NASA and Made In Space, a private space company that was founded in 2010, the 3D Printing In Zero-G Technology Demonstration experiment aims to become the first manufacturing ever conducted beyond our planet, through the 3-D printing of various test objects on the ISS. The company’s space-bound 3-D printer has already passed a series of critical microgravity tests in previous years, by showcasing that it could operate as planned during several parabolic flights on board a modified Boeing 727 airplane by the Zero G Corporation. If additive manufacturing on the ISS proves to be successful, it could greatly affect the way that spaceflight is conducted in the long run, forever changing the logistics of space exploration. “The future of space exploration will change forever when everything we need for space is built in space,” says Aaron Kemmer, CEO of Made In Space. “In this future, parts, habitats and structures are not launched and assembled, but instead 3D-printed, layer-by-layer in outer space with additive manufacturing.”
The prospect of in-space construction using only in-situ resources is something also been investigated by the European Space Agency. Collaborating with industry partners, ESA has conducted a series of studies on the feasibility of building entire bases on the Moon out of the lunar regolith through the use of additive manufacturing. “3D printing offers a potential means of facilitating lunar settlement with reduced logistics from Earth,” says Scott Hovland, Head of ESA’s Human Systems Section, in Paris, France. “The new possibilities this work opens up can then be considered by international space agencies, as part of the current development of a common exploration strategy.”
Additive manufacturing technologies hold the potential to entirely transform the way we build and operate things in our everyday lives here on Earth, as well as in space. “Just as nobody could have predicted the impact of the steam engine in 1750—or the printing press in 1450, or the transistor in 1950—it is impossible to foresee the long-term impact of 3D printing”, wrote The Economist in 2011. “But the technology is coming, and it is likely to disrupt every field it touches.” Space exploration, in particular, an endeavor that is consistently plagued with trimming budgets and constant fiscal uncertainties, could best be benefited by the advent of 3-D printing, which could allow for missions in the future that are now considered to be too risky or financially unaffordable. In the long run, 3-D printing may hold the key for the very construction and operation of deep space habitats on the Moon, Mars, and every other destination in the Solar System.
As Captain Jean-Luc Picard would say, “Make it so!”
Video Credit: NASA/Marshall Space Flight Center
The author would like to thank AmericaSpace’s Jim Hillhouse, for contributing material for the writing of this article.