That strategy could be important, even essential, on a human Mars mission, where no supply ships would be coming, so the astronauts would have to pack everything with them. Taminger has done some calculations based on NASA’s current Mars mission architecture. A Mars-bound ship would include roughly 20 metric tons of machined parts. To carry one spare for every part would add 20 tons. But if only 10 percent of the parts are likely to fail, and any one of them could be printed from a CAD file in flight, the ship would need to carry only two tons of feedstock. Printers should also, in principle, be able to reconstitute old tools and parts for use in making new ones.
Other kinds of space fixes might require a totally new part—maybe something no one has built before. 3D printing enables astronauts (or ground controllers) to design and fabricate it on the spot. By way of example, Jason Dunn of Made In Space evokes the near-catastrophic Apollo 13 moon flight, during which the crew and mission control had to jury-rig an essential air filtering mechanism using plastic moon rock bags, cardboard, spacesuit hoses, and duct tape. “If they’d had a 3D printer,” says Dunn, “they could have easily just 3D-printed that exact part that they needed.” To prove it, Made In Space spent about 20 minutes designing a part that would have fixed the Apollo 13 problem, then printed it the same day.
Astronauts don’t often need such makeshift tools, but it happens. In 2007, when one of the space station’s giant solar arrays got torn, the crew crafted six “cuff links” out of wire, strips of aluminum, and Ziploc bags, and used them to close the tear. As on Apollo 13, mission control had to figure it out on the ground first, then send up detailed instructions. Oh, to have had a 3D printer.
With astronaut time a scarce commodity in orbit, technology designed for the space station should be easy to use, and as automated as possible. Taminger says the involvement of companies like Made In Space (which counts software maker Autodesk as one of its sponsors) will bring much-needed user-friendliness to the space-based 3D printing industry. “The advantage that commercial entities have is that they’ve worked with a lot of external customers,” she says. “They’ve seen a lot of different geometries, different parts being built.” She acknowledges that NASA-built printers, which are run by the engineers who designed them, aren’t great in the user-friendliness department.
But while Dunn and Made In Space are looking far ahead to space colonies humming with 3D printers, Taminger is busy putting one foot in front of the other. Over the past 10 years, she and her team have been carefully incorporating NASA’s safety and quality standards into their EBF3 process, aiming to prove the system’s reliability before getting a chance to fly on the space station. They’ve tested their process during short periods of zero-G on airplane flights (it works), but there are many other factors to consider when bringing a manufacturing process into the closed environment of the space station. Waste products have to be contained—some materials can emit dangerous chemicals—and anything printed in orbit has to be reliable enough to be picked up and used immediately without extensive testing.
“If this is actually going to be a technology that the astronauts are going to depend on for their lives, you have to have a known quality,” says Taminger. Her task now is to convince NASA that such gear will be trustworthy.
Last year she got a break when an ammonia pump in the space station’s cooling system failed, and had to be returned on the space shuttle. The pump had to be mounted inside the shuttle’s cargo bay, and NASA engineers designed a new tool to help spacewalking astronauts secure it. Taminger used EBF3 to print part of the tool and put it through the same safety and effectiveness tests that all parts have to go through before they’re cleared for spaceflight. Her part didn’t actually fly on the shuttle (a conventionally produced tool did), but going through the tests showed NASA that 3D-printed parts can be just as good as their traditionally manufactured counterparts.
Other teams—including at least one overseas—also are working out the details of how to space-qualify printed parts. Giorgio Musso at Thales Alenia Space, an Italian company that built several of the space station’s modules and often contracts with NASA, recently completed an extensive study of 3D printing for the European Space Agency. Musso and his colleagues found that, depending on the technique used, some parts made with a printer were actually stronger than traditionally made parts, while others still needed improvement before they could have been used in space. Musso would like a chance to test 3D printers on the space station someday, but in the meantime he’s focused on the problem of printing space-qualified parts faster and more cheaply on the ground.
Made In Space, a newcomer to the aerospace world, is looking for private investment in addition to the modest amount of technology development funds it receives from NASA. The company is nothing if not ambitious. “We would love to be the people who build everything in space,” says Chief Creative Officer Alison Lewis. She laughs, but she’s not kidding. “Our long-term goal is to be the manufacturers of all structures and spacecraft in space.” Like Dunn, Lewis is a graduate of Singularity University, the future-minded educational institution based in Silicon Valley.
University of Southern California engineer Behrokh Khoshnevis is a visionary of another sort. With funding from NASA’s Innovative Advanced Concepts program, his research team is developing a large-scale additive manufacturing system, called Contour Crafting, for building structures on the moon. They would use lunar regolith—moon dust—as feedstock, possibly mixed with melted sulfur, an element also available on the moon. With liquid sulfur, no building materials would have to be transported from Earth. (If water were needed as the binder, hydrogen might have to be imported to mix with oxygen that was extracted from lunar soil.)