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One of the promises of 3D printing is its ability to deliver a wide array of objects to difficult-to-reach locations where supplies are scarce. Companies like Made in Space are taking that principle to space — arguably the most difficult and expensive location to deliver supplies of any kind.
Tethers Unlimited is moving beyond printing basic supplies and into printing full-scale spacecraft components. Right now, structures like satellites are carried into space within another spacecraft and then launched into orbit. That puts constraints on how those vehicles are manufactured, as they have to pack well. Some larger structures must be assembled in space after making the trip.
Tethers Unlimited recently received $500,000 from NASA to continue developing Spiderfab, a robotic 3D printing and assembly system that could build structures larger than half a mile wide in orbit. CEO and chief scientist Robert Hoyt believes that within two to three years Tethers Unlimited will be ready to demonstrate the technology above Earth. Within 10 to 20 years, depending on funding, there will be robots capable of assembling entire spacecraft.
Tethers Unlimited is based about a half hour outside of Seattle in the unassuming town of Bothell, Wash., its headquarters tucked into an office park off the highway. It is all business in the front, but CEO and chief scientist Robert Hoyt showed me into the laboratories in the back where well-worn consumer and custom 3D printers sat among scattered tools and scale models of 3D printed space structures.
One machine, traditionally used to weave lace and other complex fabrics, is used to make the highly customized tethers — which are basically ropes for maneuvering large objects in space — for which the company is known. Hoyt said with pride that it is the only machine of its kind in the United States.
So far, Tethers Unlimited has done studies that show it makes sense money-wise to manufacture and assemble certain parts in space. While it would be possible to build an entire spacecraft in space, right now it is cost effective to make large, light parts in space and build everything else on the ground. That includes parts like solar panels, but not electronics, which are already compact enough that it doesn’t make much of a difference.
“Eventually, in the distant future, hopefully we’ll have electronics foundries and stuff on the space station and elsewhere in orbit and we can start building that stuff on orbit as well,” Hoyt said.
Tethers Unlimited has already produced small prototypes of different parts of the Spiderfab robotic system. It will use the NASA money to begin putting the parts together and demonstrating them on a larger scale. It will also build the first prototypes of the tools the robot will use to extrude material and assemble spacecraft components.
When you send a 3D printer into space, you need to account for how things work in zero gravity. Made in Space CTO Jason Dunn, whose company will send a 3D printer to the International Space Station next year, explained to me recently that if the cogs and belts built into printers float even a fraction of an inch, it can ruin a print. And there isn’t room for error when you’re in space.
While Tethers Unlimited will have to overcome the same problem for its printer, Hoyt thinks it can actually use the lack of gravity to its advantage.
“That itself is not going to be a huge challenge. You have to tweak little things to get it to work right,” Hoyt said. “In fact, it makes a lot of things easier. On the ground, if you want to build up a complex shape that has overhanging components, you have to support that against gravity. In zero g, you don’t have to do that. You’re freer to extrude long slender things in three-dimensional space without having to build up a whole lot of support structure for it.”
Unlike Made in Space, Tethers Unlimited’s robot won’t be working within the protective walls of the ISS. Instead, it will be exposed in space.
“What is going to be be really challenging is the thermal environment in space,” Hoyt said. “In orbit, you don’t have an atmosphere … helping to cool things off and keep temperatures fairly stable. You can have huge temperature variations and that can cause shape deformations and stresses in the structure. We have to figure out how to keep everything within the right temperature range and either prevent or accommodate the stresses that are inevitably going to be there due to the different solar conditions.”
If the technology becomes a reality, it has applications far beyond Earth’s orbit. If a spacecraft wasn’t reliant on Earth for fuel or materials, it could travel farther than man has ever reached before, building communication outposts and more spacecraft as it goes.
“I’d love to be able to send a chrysalis package out to a distant star and have it get there and harvest material from that star to build a giant [structure] that it would need to both survey that (solar) system and beam the data back to us,” Hoyt said. “To communicate with really distant probes, you need really big [structures] and it is extremely expensive to send it all out there. It would be better to get there and build it itself. I think this could fit into systems for building habitats out on Mars or other planets, out at the asteroids. A whole bunch of different potential applications.”