NASA to test 3D printer on space station
Astronauts could make their own spare parts if the technology can conquer a zero-G environment. Cathal O'Connell reports.
NASA has sent a specially designed 3D printer to the International Space Station to be put through its paces. If it passes the test, the agency hopes astronauts will in future be able to make perfect spare parts in a matter of hours – perhaps saving their lives, or salvaging expensive missions that would otherwise have to be abandoned.
There’s no doubt Earth-based printers can do the job. But the crucial question is whether they will work in space.
Grant Lowery from Made In Space, the company that designed and built the microwave oven-sized machine, is confident.
“Very soon we’ll be building things regularly away from the Earth,” he says.
The printer uses a computer-generated template to create objects out of the same plastic used for Lego blocks. A nozzle deposits layers of the melted plastic, like piping icing on to a cake, to build up the object. As each layer cools and solidifies, the next is added.
It will attempt to make 21 test parts on the ISS, including tools and facsimiles of the space station’s parts.
Made In Space’s initial attempts to print in low gravity using an off-the-shelf machine failed. When tested on the “vomit comet” – the aeroplane that simulates low-gravity conditions – the layers failed to stick together and the printed object turned into mush.
'Once we can mine local materials found on the Moon and asteroids,
we can send the hardware up and have it create what we need.'
One problem was that heat transfers differently in low G than on the ground (on Earth heat rises, but in space there is no such thing as up) and this affected the melting and cooling of the plastic.
So the team designed a new printer, using a slightly different process, and last year another test on a low G flight was a success.
The company is secretive about the process, which it calls its “secret sauce”, but says using surface tension was key to making the layers of plastic stick together.
While the success in low G is promising, astronauts will only be able to make a limited range of useful objects from Lego plastic.
So while a printer may have helped on Apollo 13 in 1970 when the crew cobbled together a CO2 filter using cardboard, a plastic bag and some duct tape, it probably wouldn’t be much more use than the toothbrush two astronauts on the ISS used in 2012 to unscrew a stubborn bolt.
“You can make a spanner from it, but would it lock a steel bolt in place without breaking? The answer is no,” said Stephen Beirne, Additive Fabrication Manager at the Australian National Fabrication Facility (ANFF), at the University of Wollongong, Australia.
Printers will need to be able to work with metal to manufacture objects such as satellite parts, and Beirne says that will require major innovations.
Lowery agrees, but says the current space printer is “a proof of concept” that will lay the groundwork for the next stage.
For now, the parts printed on the ISS will be returned to Earth and compared for strength, durability and shape with objects printed on the ground. These experiments will inform the design of the next-generation space printer, slated for deployment on the ISS permanently in 2015.
“We see additive manufacturing as an essential tool for space development,” says Lowery. “Once we can mine local materials found on the Moon and asteroids, we can send the hardware up and have it create what we need. It’s a paradigm shift in our approach to space.”