Recycling Plastic is Hard on Earth—but Next Year NASA Will Do It In Space

Space travel favors light packers, since launching a single pound of stuff costs an eye-watering $10,000. But NASA likes to be ready for anything, which is easier with more supplies. So what's an agency on a budget to do?

Next spring, the International Space Station will get a new piece of equipment designed to help tackle this problem. Called the Refabricator, it's a mini-fridge sized machine that can take a plastic component, melt it down, and print a new component out of the same plastic. It's the first machine to combine recycling and 3D printing into one device, even here on Earth.

But while its destination is the ISS, it's aimed at NASA's goal of going much farther. It takes just a few hours for a resupply mission to reach the space station, but NASA has its eyes set on the Moon and Mars. "That's a very different model," says Niki Werkheiser, who specializes in in-space manufacturing at NASA. New supplies would take weeks to reach the Moon and months to reach Mars—and that kind of transit time makes forgetting your keys very unappealing.

NASA has been intrigued by a 3D-printing "MacGyver box" as a solution to the hazards of an incomplete packing list for a long time. In 1999, the agency put a 3D printer on the so-called Vomit Comet, a parabolic flight that produces 25-second spurts of weightlessness to test how the process could be affected by gravity changes. But at the time, Werkheiser said, patents covering 3D printing made doing things with the technology more complicated.

That meant the space station didn't get its first 3D printer until 2014. Its successor, the Additive Manufacturing Facility, was launched last year, also run by a commercial company, called Made in Space. The machine prints both for NASA and for customers on Earth.

But those machines still need to be fed fresh plastic, with its large launch price tag. "If you have to launch all of the raw feedstock, how is that really helping?," Werkheiser says.

That's where the Refabricator's recycling side comes in. Recycling plastic on Earth is both expensive and inefficient—and that's before you add in the unique constraints of the space station, like microgravity and strict safety rules.

Typically, plastic recycling first pulverizes the material into a powder (Rachel Muhlbauer, who leads research and development at Tethers Unlimited, Inc., compares it to a coffee grinder), then uses a different machine to turn it into new base plastic.

But that isn't an option in space, where the absence of gravity makes any form of powder a serious danger to astronauts. So the Refabricator instead melts the plastic down to create a new base material, called filament—and it turns out that does less damage to the plastic itself, which means the same material can be used more times, without needing to be diluted by fresh, non-recycled plastic. "A lot of the terrestrial ways of making filament generates a lot of waste," Muhlbauer said. The Refabricator avoids that. "You put the material in and you get that material right back out."

Another quirk of the space station means these devices benefit from being as autonomous as possible, since there's limited staff to watch over their work. "Astronaut time is very valuable and very hard to come by," Werkheiser said. In fact, the Refabricator will be run entirely from Earth, only relying on astronauts to take new products out of the machine.

But the heavily controlled environment of the space station does save the Refabricator from having to deal with one major challenge of recycling plastic on Earth. Here, each different flavor of plastic, from the flimsy rarely-recycled compound in shopping bags to the hefty formula in milk jugs, behaves slightly differently during the recycling process. That means they must be sorted, at least into general categories before going to the recycling machines, and even still, recyclers often have to discard batches because of contamination.

Instead, the Refabricator works with only one type of plastic, called Ultem, which is particularly sturdy. When space recycling takes on more flavors of recycling, the sorting problem will remain.

Nevertheless, that's NASA's next goal, particularly to incorporate a type of plastic called HDEP, which can be used for medical purposes. In the longer term, Werkheiser hopes proposals to a project called FabLab—short for fabrication laboratory—will be able to mix plastics with metal and even electronics printing, since more than a quarter of issues on the space station have to do with electrical components.

The FabLab will build both on the tests she and her team are running on the Refabricator between now and its launch next year and on how the machine performs in space. "I didn't want to jump the shark off into Star Trek world and bite off something that was impossible," Werkheiser said.

Both Werkeiser and Muhlbauer think the advances coming from the Refabricator and its successors will prove valuable on Earth, as well. Werkheiser says the Department of Defense is following NASA's work, since although troops don't deal with microgravity, they do work in small spaces with limited skills, safety concerns and tight timelines.

"All those things that we are designing to make it perform on station in a safe way only makes it safer on the ground," Muhlbauer said.