​3D Printing in Space Is Really Hard

One day in the future, humans might jump ship from Earth and move to space. But with resupply missions from Earth proving both lengthy and costly, we'll need to produce our supplies in space. What will we need for that? The answer: a 3D printer.

In September 2014, NASA engineers working for the "3D Printing in Zero-G Project" sent a 3D printer up to the International Space Station on SpaceX's​ fourth mission. The a​im was to demonstrate that a 3D printer could still work in microgravity conditions. This was proved when images of astronaut Barry Wilmore proudly clutching a 3D printed wrench made Reddit's space page go bers​erk.

The experiment tests how the ISS's microgravity environment will affect the additive manufacturing process.It's also testing out the idea of having an in-station space shop, where in-space manufacturing will be possible. This will be critical in enabling deep space missions, as astronauts won't have to wait for lengthy resupply missions to arrive from Earth.

The 21 parts 3D-printed in space came back to Earth earlier ​this month. So what have the team learned so far? What kind of challenges does 3D space printing pose? And what kind of objects will astronauts need? I spoke to principal investigator for the 3D printing in Zero-G Project, Quincy Bean to find out more.

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MOTHERBOARD: You're the principal investigator for the 3D Printing in Zero-G Project at the NASA Marshall Space Flight Center. What does your job entail?
Quincy Bean: ​As the principal investigator, I make up the test plans for the parts that were built on orbit as well as on the ground. I also conducted an ABS (Acrylonitrile Butadiene Styrene—a type of plastic polymer) characterization study that made similar mechanical samples to the ones that were built in space, and the ground control samples. I made large batches of those samples to test, so that I have a good statistical basis to compare the data to, when we get back the data from the flight and the ground samples back.

[ABS is the] material we use to make the parts. We made compression samples and flexer samples, and then we made large batches of each of those using different ABS feedstocks and different machines to build them on. This was mostly to try and see if there's a difference from machine to machine, or from feedstock to feedstock, or to see if there's any difference in mechanical properties.

What kind of scientist are you and how did you get involved in 3D printing in space?
​I'm a materials engineer. My specific job title is aerospace engineer and my education is in spacecraft propulsion. I have a master's in Astronomical Engineering from USC.

My supervisor is Ken Cooper, and I started working in his lab two years ago. He passed the principal investigator responsibility onto me. Ken Cooper spearheaded the concept of 3D printing in space back in the 1990s. For some of his early experiments they took a 3D printer on the KC-135—that's the parabolic flight that NASA does. They tried 3D printing in zero gravity and the results that they got from that were pretty successful from the parts that they got made within the limited microgravity in the parabolic flight. They thought this warranted further study, so they called it the Small Business Innovation Research and put out a call for different companies to build a 3D printer and put it on the space station. A company called Made in Space based in California won the contract.

Could you explain the process of 3D printing in space?
​We used a filament deposition modelling process. There are several companies that make filament deposition modelling machines here on the ground—for example, Makerbot, 3D Systems, Cube Printer. The process works by taking a plastic filament which is extruded through a hot tip (basically it's like a computer-controlled hot glue gun), which heats up the plastic almost to melting point to get it malleable.

The extruder head is computer-controlled. When you put a file into it, the file tells the extruder head exactly where it needs to go to extrude out material and build the part. The extruder head passes back and forth in a hatch pattern that makes the one layer of the part, then the build tray drops down a little, and the extruder goes back over and makes the next layer, as it moves it extrudes out the plastic like a tube of toothpaste. As the extruder passes the plastic cools and hardens. Once it's done you have your part built.

The reason why this process was chosen for use in space was because the filament is very easy to control in zero gravity. A lot of the other additive manufacturing processes use a powder or a liquid resin. Those would be very hard to control in microgravity. For instance, for the powder, you'd require a flat bed of powder. Without gravity that powder bed would just be a powder cloud, so you wouldn't be able to make anything with that. The powder would also be extremely hard to handle in microgravity.

The space station is very strict about what you can put up there. If that powder got out it would be a bad day for the space station. The liquid resin would be similarly hard to handle because the additive process that uses the resin requires a vat of resin. Without gravity that vat would just be a big ball floating around.

What are some of the challenges you face? Can anything go wrong?
​We haven't seen anything go too terribly wrong with the process that we use. The biggest problems we've seen are the parts sticking too well to the build plate that the 3D part is built upon. We need a flat build surface to build the part and a lot of times the part would be too stuck and kind of broke off as the astronauts were taking the parts of the build plate.

For the next phase we're going to investigate why they stuck too much. We're going to see if that's the microgravity effect, or not. If it's a microgravity effect, we can learn to work around it and design our parts accordingly so we don't have that problem in the future. Ultimately this is why we do these experiments, so that we can learn from it and do better on the next iteration.

What are the most important objects that astronauts will need to print out in space?
​Right now we're looking at replacement crew tools for the astronauts. Things like wrenches and screwdrivers or just any sort of tool that they might need. There's a lot of nooks and crannies that they can't get into so we're working on designing a better vacuum cleaner attachment to get into the smaller cracks. Imagine living in your cars for years and years, and having to clean that now and then.

We're also looking into replacement parts for life support systems. We're start out with less mission critical systems first, so not necessarily life support systems, but little things like cabinet knobs. Simple things like that that might break or come off, and then we'll work into more critical systems like life support. We issued a challenge a couple months ago to the GrabCAD community (a group for CAD designers) to make a handrail clamp. There is an existing handrail clamp that the astronauts use made out of metal. We issued a challenge to design a plastic filament deposition modelled handrail clamp that would go over the same handrail in space.

Handrails are a standard part that's all over the station. They help astronauts navigate through the station. What this handrail clamp does is it clamps on and has a seat track connection, which is also standard connection in aerospace. Even all the airline seats are connected with the same seat track rails. It's a clamp that has one of these rails on it so that they can attach something like a camera mount to that if they need to mount a camera there.

What's up next, and what excites you most about 3D printing in space?
​We're working on implementing a phase two in a couple of months. For that I'm drawing together the parts list and deciding which samples to build.

So we'll print another round of parts. Phase one was 21 parts, this will be about 35 parts. There will be a few more mechanical samples. Most of the parts will have more practical applications like the handrail clamp or the vacuum cleaner attachment.

I grew up watching Star Trek and Star Wars. I'm a big sci-fi nut in general, so what excites me most about 3D printing in space is that if we really want to have increased human presence in space, we really have to have the capability of building what we need in space, instead of having to launch spares over and over again. So to really increase our range as to where we can explore, when we go back to the moon or mars or to asteroids of wherever we want to go.

If we have the 3D printer on the spacecraft, the astronauts can build what they need when they want it and ultimately increase their range and self-sufficiency because there's probably not going to be a resupply mission to Mars if they forget something or if they lose something. Ultimately, if you want to build anything big in space, you're going to have to manufacture things in space and not launch them from the ground all the time.