The machine is expected to let astronauts create parts to order

Engineers test a 3D printer under microgravity conditions aboard a modified aircraft in parabolic flight. Credit: Made In Space

In one small step towards space manufacturing, NASA is sending a 3Dprinter to the International Space Station. Astronauts will be able to make plastic objects of almost any shape they like inside a box about the size of a microwave oven enabling them to print new parts to replace broken ones, and perhaps even to invent useful tools.

The launch, slated for around September 19, will be the first time that a 3D printer flies in space. The agency has already embraced ground-based 3D printing as a fast, cheap way to make spacecraft parts, including rocket engine components that are being tested for its next generation of heavy-lift launch vehicles. NASA hopes that the new capability will allow future explorers to make spacecraft parts literally on the fly.

Space experts say that the promise of 3Dprinting is real, but a long way from the hype that surrounds it. Theres been a tendency among the space-enthusiast crowd to treat 3Dprinting as if its a magic technology as if all you have to do is wave your wand, say Abracadabra, heres a 3D printer, and its going to build you a Moon base, says Dwayne Day, a senior programme officer at the National Research Council in WashingtonDC who oversaw a recent report on 3D printing in space (see go.nature.com/j6z5mq). In reality, Day says, the technique is an important component of a much broader technology base that is being developed and advanced.

The printer selected by NASA was built by the company Made in Space, which is based at a technology park next to NASAs Ames Research Center in Moffett Field, California. During the printers sojourn on the space station, it will create objects from a heat-sensitive plastic that can be shaped when it reaches temperatures of about 225250C. The team is keeping quiet about what type of object it plans to print first, but the general idea is to fashion tools for use aboard the station. If you have 300different things that could break on your spacecraft, you may not need to carry replacement parts for all 300of them, says Day.

The Made in Space printer is also a testbed for performance of the technology in near-zero gravity. The machines work by spraying individual layers of a material that build up to form a complete, 3D object. But in near-weightless environments, there is no gravitational pull to hold the material down.

In test flights aboard vomit comet aircraft that fly in a parabola to create almost weightless conditions, Made in Space discovered that the layers of printed material varied substantially in thickness as the aeroplane cycled in and out of microgravity. By modifying the printer, the team got the layers to come out at roughly the same thickness.

Thermal issues could also be a problem. Heat flows differently in microgravity, which could mean that parts of the plastic become too hot or too cool for the printing to work properly. Whether it works fantastically or we have some issues, were going to learn things that will play into the design of future machines, says Michael Snyder, the companys director of research and development.

Made in Space is looking at flying a second printer to the space station next year, incorporating design changes from what is learned during the first flight. To evaluate the printers performance, parts made aboard the space station this time will be flown back to Earth and tested to see whether they work as well as Earth-made materials do. There is little point in manufacturing parts in space if they do not work at least as well as spares that an astronaut might grab from a storage locker, Day notes. Time is also an issue: Made in Spaces prints typically take between 20 minutes and two hours, which might not be useful, depending on the urgency of the situation.

Read more:

NASA to Send 3-D Printer to Space