Brian Trease, JPL Mechanical Engineer, uses origami principles to design large-scale and small-scaled deployable structures. In 2013, Trease collaborated with experts to develop an 82-ft circular solar array that folds up to be 8.9 feet in diameter.
NASA Tech Briefs: How can the principles of origami be used to design spacecraft?
Brian Trease: We started looking at origami as a way of doing storable and deployable large-scale structures. Most of the time when we do these things, like the Space Station panels, we use simple accordion folds. I’d like to say that we really went outside of the box to use origami, but really I think that's the next logical step when you're looking for any novelty in your folding schemes. Origami has been around — there might be references that go back a thousand years — for maybe a few centuries. A lot of the art that was done for a long time was very simple: the things that we're familiar with from elementary school, like the cranes and fish. It was only about 100 years ago when the art really took a new dimension. Someone came up with a diagrammatic way of capturing origami folds. Even more recently – I'd say about 40 years ago – the mathematicians dove in and really explored where they could go with it, and not necessarily knowing to what end they were doing it; it was just kind of an interest. It enabled the artists to do much more inspired and advanced designs, and the engineers kept watching. Everyone worked together. It's a really neat field. It's at the nexus of engineering and art and culture, and all sides are benefitting along the way. Recently, there have been some new applications demanding more advanced packaging schemes for various arrays. We started off by contacting one of the preeminent minds in origami engineering.
NTB: What'd you first develop that used the origami principles? Was it the solar array?
Brian Trease: Yes, it was that solar array, based on a paper design that's called a flasher. When you pull two edges of it, it flashes up into a big circle, then shrinks again. That's the paper design. That's one of the challenges of doing anything with origami. Origami always assumes a zero-thickness material, a paper. Our challenge is to build something that actually has thickness. That pushed us immediately right into the math, and we had to write algorithms and code that allowed us to accommodate the thickness of panels. At every fold line, if you have multiple folds, the bend thickness accumulates. You have to plan for that ahead of time or else you get all kinds of jamming in origami. We developed a nice, robust means of doing that as we were fabricating the solar array. We’re calling it the HanaFlex now. Hana is the Japanese word for "flower." If you watch this deploy, it actually looks like a flower blooming. It expands out radially from a central hub and kind of rotates as it's doing it. As you watch it with all the panels in there, it looks like a complex motion. All of the panels there are "rigidly deployable". That means they're not necessarily flexing, and if you want to put something delicate on there, like solar cells, the origami techniques can accommodate that without putting extra stresses into them.
NTB: So what can be done with the finished product of these foldable solar arrays?
Brian Trease: One of the things that inspired us was looking at solar electric propulsion. There was a call out from NASA looking for how we can do large arrays with alternate means. And we're talking arrays that might have a 150-300 kilowatts output. For reference, the International Space Station is putting out about 84 kilowatts. We're looking at a design to generate similar kilowatts. The application here is solar electric propulsion, where you use energy collected to potentially drive ion thrusters for something like an asteroid retrieval mission. To get this kind of large structure, some people are using typical fan folds to get that kind of area. We like our packaging. We offer a unique alternative, in the way that we can stow around the hub of the spacecraft. If you look at the fairing of an Atlas V rocket or even something bigger like SpaceX's Falcon 9, the panels can wrap around the hub of the spacecraft. When it deploys, it can deploy out to 30 or 40 meters flat. What’s nice is it deploys out symmetrically, radial out from the spacecraft. If you're worried about spacecraft dynamics, you don't have awkward panels hanging off like appendages. And if you want to rotate your spacecraft, all of your momentum is more balanced. In fact, saying that, here's another possibility: The deployment itself could be centrifugally based, where we spin the spacecraft to either fully deploy or assist the deployment of the panels to the final configuration.
NTB: What are you working on now with these types of designs?
Brian Trease: Going big made origami potentially of interest. Going small makes origami of interest as well. Right now there's a lot of interest in the SmallSats. There's the whole CubeSat movement going on with all the universities, and we're increasingly interested in those as well. Everything that we're experts in for traditional spacecraft engineering doesn't necessarily scale down to a package like a CubeSat, which is roughly 10 centimeters on a side - up to 30 centimeters on a side for the longer ones. All the hinges and hardware that would go with a traditional deployable just don't scale down. In fact, origami, with the simplicity and elegant and efficient use of material, might be the only solution for some of the deployables we're looking at. We're looking at deployable antennas, with a possibility to do a deployable reflectarray, which is a kind of tuned antenna. One question that we don’t know the answer yet to is: How can we do deployable structures that have a parabolic shape? We recently had a workshop here at JPL discussing origami engineering and directions to go, and that was one of the key questions on what we can do, to do a parabolic reflector that deploys in a similar fashion.
NTB: What is the challenge with a parabolic shape structure?
Brian Trease: Getting a precision parabolic shape for a reflector or antenna dish. Right now, the deployable we're doing deploys out to a flat sheet, which does have some applications, but there's many more if we can get precision-engineered shapes, such as curved reflectors. The latest project that we’re working on now: NASA has a big technology program called the Starshade. I just started on this program. I'm not the expert in it, but I'm learning a lot right now. The Starshade is going to be a 34-meter deployable disc up in space that works in tandem with a telescope. It's a precision optical system for doing imagery of the planet’s orbiting distant stars. It works in tandem with a telescope that’s about 10,000 miles away, both in orbit. The disc blocks the starlight so that the telescope can see the planets orbiting it. It's a big precision deployable, and right now there are a lot of elements to it, including deployable trusses. What we have less experience in is the actual covering: the blanket that's going to block the light and how that stows in tandem with this large truss structure. Initial thoughts are we're looking at some of the origami techniques for a design that’s similar to the HanaFlex design.
NTB: Can the origami principles be used for utilizing space solar power for Earth-based purposes? How realistic is that?
Brian Trease: I think an architecture like we're looking at makes it much more realistic. Right now it's a field of interest to a lot of people, but there are a lot of high hurdles that need to be overcome. One is generating lots of these large deployable structures that can be put up high into orbit, perhaps geosynchronous orbit, simply and at a cost level that’s economical for generating power. The premise is that these structures collect solar power and then beam it back down to Earth via microwave to stationary collectors on the Earth. It can operate on solar 24 hours a day, depending where you place your satellite. Each one of these collectors that we send up would be done in one launch. The entire array can deploy in one launch and have the right circular shape. Other architectures would propose having a robotic assembly in space or something like that.
NTB: Have you always had an interest in origami, or did this occur later when you were doing your engineering work?
Brian Trease: I had an interest in origami. It was a long time ago. It's been a discontinuous interest, but definitely in the elementary and junior high and high school I was always grabbing books out from the library and studying the different patterns and trying things out. In fact, I was even in Japan as an exchange student in high school 20 years ago. I was recently looking through a photo album, and there's a picture of me in a Japanese McDonald's in the city of Himeji. I'm folding origami cranes out of a burger wrapper. I have a documented history in the field! I took all the years of graduate and undergraduate in mechanical engineering, and never thought of it again as having real engineering potential until we started working with some of the experts here. I had the same perception problem that a lot of people have. I saw it as a toy, a child's item, and didn’t see the promise that it holds. That’s where we're at now: doing these demos and showing people that it’s much more than a toy. It can be very elegant in solving some of our engineering problems. Once we show that, then it flips; the public becomes very inspired. A lot of people can relate to the origami array when they see it, and know they can fold something like that on their own in their free time.
NTB: What are your short-term goals for this? Is it about demonstrating the possibilities?
Brian Trease: We're definitely trying to find the possibilities and more applications. The prototypes we've done right now have been done with dummy solar panels. One of the things we'd like to explore is the electrification of these panels and all of the issues that come with that. For example: How do you run power across fold lines? We can think of a lot of solutions that we want to work at. That'll be the next steps. We also want to do something on the CubeSat scale, the little 10-cm satellites. They offer a good platform to try novel, new things without the cost of large spacecraft. I think some of these small antennas and curved antennas can be done at that scale. We’re working on some designs for that and trying to find the right partners and missions that would be willing to fly that.
NTB: What is most exciting to you about this work?
Brian Trease: Right now we're just folding one material and maybe putting some solar panels on it. But I see everything being done in that 2D process, where you have the material, you have the fold lines, and you could have your electronics printed on to it. There are companies that print solar panels; you could have your solar printed on to it. You could do all your batteries, various shielding, and all of these 2D manufacturing processes very simply and then have it folded into your three-dimensional structure when you're done. 3D printing is the big buzz right now, but I think there's a lot that can still happen with 2D printing that we enable with origami techniques. 2D manufacturing processes are much easier to translate and potentially put up in space, or bring to another planet if you want to do fabrication in other extreme locations.
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