Recyclable 3D Printing Preps for the Space Station
Michael Molitch-Hou posted on September 18, 2017 | 9222 views

In-space manufacturing is a very young industry, but the space race is already heating up. With two 3D printers aboard the International Space Station (ISS), Made In Space would have seemed to have the field on lockdown. However, another firm, Tethers Unlimited Inc. (TUI), has also been involved in developing space technology is now—through its in-space manufacturing division Firmamentum—prepping to send its own 3D printer to the ISS.

The mini fridge-sized Refabricator is capable of recycling and 3D printing with space-grade ULTEM plastic. (Image courtesy of NASA/MSFC/Emmett Given.)
The mini fridge-sized Refabricator is capable of recycling and 3D printing with space-grade ULTEM plastic. (Image courtesy of NASA/MSFC/Emmett Given.)

Firmamentum’s Refabricator system is no ordinary space printer. The machine, which is currently slated to head to the Space Station next year, can both recycle and 3D print the high-performance plastic known by the brand name ULTEM.

The Refabricator project is just one part of a much larger venture into in-space manufacturing by the Seattle-based firm. ENGINEERING.com spoke to Tethers Unlimited CEO Rob Hoyt and Allison Porter, the project manager for the Refabricator project and the Flight Mission Manager for TUI.

The Refabricator

The Refabricator project was initiated in 2014 with a $125,000 Phase I Small Business Innovation Research (SBIR) grant, with which the company was able to develop its Positrusion recycling system, which would go on to form the recycling half of the Refabricator project. Since then, TUI has garnered multiple grants that it has used to extend the project and develop other in-space manufacturing techniques.

Now, according to Hoyt, Firmamentum is preparing its Refabricator system for a potential launch next year. “NASA is getting comfortable with the project and it’s getting close to being ready to fly,” Hoyt said. “They have continued funding and, at this point, we’re funded through launch and operations.”

A graphic illustrating the Refabricator project from TUI’s Firmamentum division. (Image courtesy of TUI.)
A graphic illustrating the Refabricator project from TUI’s Firmamentum division. (Image courtesy of TUI.)

The Refabricator will stand out among the other additive manufacturing (AM) machines on board the ISS in that it will not only 3D print parts, but also recycle them. And it does this as part of one continuous process that will, for example, enable an astronaut to drop a used plastic component into the Refabricator, which will then convert the material into filament for 3D printing.

Hoyt and Porter explained that the Refabricator’s Positrusion process is designed to meet the safety requirements of the microgravity environment of the ISS and the performance needs of space equipment. Recycling systems typically associated with 3D printing on Earth grind used plastics down into fine granules, which are then fed into an extruder to be converted into filament.

“We don’t use a grinding process because that can actually degrade the quality of the plastic,” Porter said. “It maintains some of the strength properties better if you perform more of a melt process, which is what we’re using for our recycler.”

Hoyt added, “On the space station, everything has to be extremely safe. In addition, astronaut time on the station is an extremely precious resource. It’s very difficult to get even a few minutes of astronaut time per month. So, we had to design the system to be highly autonomous to require absolutely minimal interaction by the astronauts and we had to design it to be very safe.”

The Positrusion process avoids the risk of dust that might occur with a grinding process by instead melting the plastic down. And, while typical recycling systems require a great deal of user intervention and the exposure of hot melted plastic, the Positrusion system is highly automated. As a result, recycling and 3D printing with the Refabricator requires very little astronaut time.

“An additional benefit is that it produces filament that has much higher dimensional quality or consistency than you see even with the high-end commercial 3D printer filament. We believe that that will translate into better build quality and strength out of the parts that we make,” Hoyt said.

The Refabricator was designed, from the start, to work with ULTEM, an engineering-grade plastic that not only has a very high melting temperature and very low outgassing properties, but also is already approved for use in space applications. By demonstrating the technology’s ability to recycle and print ULTEM, the Firmamentum team knows that it will also work with other plastics.

3D Printing for Long-Duration Space Missions

Among those other materials that the Refabricator can work with would be food- and medical-grade plastics that could be used to 3D print new utensils and implements. Dubbed the ERASMUS project (named after the patron saint of sailors and stomach ailments), this technology would go a step beyond the Refabricator by integrating a dry heat sterilizer that can sterilize pre-used materials and then recycle them into 3D printer filament.

This technology would be key for long duration space flight to Mars, according to Hoyt, because there are a number of medical and food items that would need to be reused throughout the trip.

“For example, recently we have been fabricating a whole lot of urinal funnels for the space toilet,” Hoyt relayed.“Not a very glamorous job, but on a mission to Mars, the astronauts would need hundreds or thousands of these things over a period of a couple years and launching them all from Earth and using them a few times and throwing them away would be extremely expensive and wasteful.”

Another item that the team is working on are ear specula, those little black cones your doctor uses to shine a light into your ear. “On the space station, the astronauts’ ears have to be checked fairly frequently—roughly once a month—to make sure that the microgravity environment isn’t causing degradation of their hearing and balance,” Hoyt said.

With ERASMUS, it would be possible to take used ear specula or urinal funnels, clean and sterilize them, and then melt them down to 3D print more for subsequent use. If NASA wants to perform deep space, long duration missions in the mid-to late 2020s, the organization has to get the technology prepared now. By getting the Refabricator onto the ISS next year, Firmamentum will be more likely to see something like it sent on the first deep space mission.

Manufacturing Satellites in Space

The Refabricator and ERASMUS will both go along way toward reducing reliance on launching costly, heavy payloads from Earth, but in-space 3D printing is just one part of a larger strategy for constructing objects in orbit, which includes something called SpiderFab.

Initially funded by a NASA Innovative Advanced Concepts (NIAC) grant, the SpiderFab program seeks to fabricate and assemble key satellite components in space. Originally, TUI aimed to rely heavily on 3D printing for the project, but, analyses showed that 3D printing would be too slow and produce parts that were too weak for building a kilometer-scale antenna.

The Trusselator is meant to fabricate trusses, which would be robotically assembled into large-scale structures. (Image courtesy of TUI.)
The Trusselator is meant to fabricate trusses, which would be robotically assembled into large-scale structures. (Image courtesy of TUI.)

With NIAC Phase I and II funding, TUI developed the Trusselator, a system for producing trusses that are made from fiber composite materials using what Hoyt described as a combination of 3D printing, composite filament layup and robotic assembly. In the videos below, you can see several demonstrators: the first shows the Trusselator fabricating a 10-meter-long, 340-gram carbon fiber truss; the second demonstrates a Baxter robot using machine vision to manipulate a truss; and the third exhibit shows how a thin, film-based solar array might unfold out of the Trusselator system.

 

 

By using carbon fiber, with fibers oriented for optimized strength, the company has demonstrated that it’s possible to create remarkably strong, lightweight structures.

Though the NIAC funding has since ended, the SpiderFab project has continued in various forms. For instance, Firmamentum is also working with Space Systems Loral (SSL) to demonstrate in-space robotic assembly of geostationary (GEO) communications satellites through SSL’s Dragonfly program, which is funded under NASA’s Tipping Point initiative. The Dragonfly program will be the first to validate Firmamentum’s Trusselator technology.

Hoyt said that the company recently performed thermal vacuum testing of the Trusselator and that, once SSL signs a commercial customer to fly the Dragonfly project, or Firmamentum obtains the necessary funding, the company could have a flight demonstration ready to fly in about 18-24 months.

Demonstrating the abilities of the Trusselator would lay the foundation for even grander projects. Last May, Firmamentum received a DARPA SBIR award with SSL, NanoRacks LLC, and Vulcan Aerospace to create a persistent GEO orbit satellite platform. Under this project, Firmamentum hopes to launch “suitcase-sized modular elements” and robotically assemble them to create a space station for “providing power, communications, station-keeping and other services.” The ability to fabricate trusses and reflectors on orbit would make it possible to create “large, stable platforms” that could be expanded over time.

Under a recent DARPA Direct-to-Phase II SBIR contract, Firmamentum is developing OrbWeaver, a system meant to combine a variety of technologies developed at TUI. The OrbWeaver would take an aluminum structural element of the rocket that sent it into space and create a large, high-precision antenna reflector. OrbWeaver would then connect the antenna to an array of radios to create a small satellite that would runon TUI software.

OrbWeaver’s ability to recyclea portion of the rocket on which it was launched would help the company demonstrate the ability to manufacture using materials found in space. Hoyt explained,“The initial plan is to launch raw materials into orbit from Earth, but longer term, we want that architecture to be adaptable to use resources that we can acquire in space—ultimately, resources like asteroid material, regolithor whatever else we can get out there. An intermediate stage is to gather and reprocess materials that we already launched into space—space trash, waste on the space station, old satellite parts—and turn them into feedstock we can use to build stuff.”

To tackle the issue of recycling and manufacturing with metal, TUI was awarded a NASA SBIR grant this past April. With it, the company will develop Metal Advanced Manufacturing Bot-assisted Assembly (MAMBA), a metal version of the Refabricator that will be configured as an EXPRESS-Rack payload for the ISS.

3D Printing on Earth

Once the Refabricator heads up to the ISS, the Firmamentum team will begin studying how well recycled material stands up over time in a microgravity environment, according to Porter. Tests have already been conducted on the recycled material back on Earth, which suggest that, even after being recycled numerous times, 3D-printed plastic will retain much of its original qualities.

“So far, we’ve done about seven cycles of recycling on Earth with this plastic using the Positrusion recycling technology, and we’ve demonstrated that minimal degradation [occurred] over the seven cycles, about a 20 percent loss in strength properties, which is really good,” Porter said.

The recycling and 3D printing portions of the system are each about the size of a shoe box and, together, the entire Refabricator is about the size of a mini fridge, said Porter. This fact makes it not so difficult to imagine the system being used in your office. In fact, Hoyt said that TUI does have plans to eventually commercialize the technology for the industrial and prosumer markets.

Once such a machine did hit the market, it would give users an unprecedented ability to recycle plastic parts while maintaining much of the integrity of the original material. Before you can get the Refabricator in your office, however, Hoyt said that the company is focused on getting one up to the space station.


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