

MOFFETT FIELD, Calif. (NASA PR) — Assembling large structures in space is an enormous undertaking, and the International Space Station, or ISS, which is longer in length than a football field, is the prime case in point. Its construction was challenging. First, the modules, or compartments, had to be built on Earth, where engineers have access to tools for piecing together an agglomeration of parts. Then, apart from being of suitable size to fit within the rocket fairing, each module had to be structurally reinforced to withstand the violent turbulence of launch. Once in space, a tricky rendezvous-and-docking sequence was employed to join them all together.

The ISS is no doubt an out-of-this-world wonder of ingenuity, but NASA is exploring another technology that could turn the current paradigm of giant spacecraft and aircraft manufacturing on its head.

As a graduate student at the Massachusetts Institute of Technology (MIT), Kenny C. Cheung, now a structural materials research scientist at Ames Research Center in Moffett Field, Calif., was looking for a new approach to constructing intricate things such as spacecraft and airplanes, which require many specialized parts that must be put together like an insanely complicated jigsaw puzzle. “Take a Boeing 747,” Cheung says. “It requires 6 million parts to build one of them, and about a million of them are unique parts. Spacecraft are made the same way, with a lot of specialized pieces that cost a lot of time and money to make.”

With goals of simplifying and reducing the costs of the manufacturing process while maintaining flexibility of use, Cheung and his advisor developed flat, geometric carbon-fiber composites that can be linked together into a three-dimensional lattice, forming any kind of object on any scale. They’re also lightweight, strong (10 times stiffer than other ultralight materials), and can be disassembled and reassembled in order to repair damage or to take on new contours and shapes. What’s more, these components can be affordably mass-produced and, because of their simplicity, are cheaper to simulate because only a single analytical model is needed, whereas traditional methods use thousands or more.

“You can build the hull of an entire aircraft using these kinds of parts,” Cheung says, adding that when these composites fail, they fail incrementally rather than suddenly, making them safer and more easily repairable than their conventional counterparts.

With funding from NASA’s Aeronautics Research Institute, Cheung and collaborators at Ames and NASA’s Langley Research Center in Hampton, Va., have already tested a prototype 4-foot wing using only eight different composite types. Wind tunnel tests show that the prototypes hold up well to aerodynamic forces, so much so that the model wouldn’t break even when the team purposefully tried risky dynamics tests that could tear them apart. The next step, besides automating the process, will be applying shape-morphing technology to the wing, which by itself is an entirely up-and-coming technology that aims to increase maneuverability and fuel efficiency while also reducing noise pollution.

As if that concept isn’t innovative enough, Cheung’s current work under the Space Technology Mission Directorate’s Game Changing Development Program has an even more ambitious end goal: to design a self-assembling and -repairing spacecraft using what are called digital materials.

Imagine a crewed spacecraft, a huge one, built with the same composite components, only each panel is computerized, possessing a processor chip, sensors and its own power source. The panels are able to pass along information, whether it’s payload data for a research mission or damage taken by radiation or space debris, to antennas and other nerve centers that store information and give marching orders to other computers. In case of structural damage, robots are sent to replace panels and heat shields and anything else that’s needed to repair the spacecraft, which means that astronaut extravehicular activities are not necessary. But the robots do much more than repair the spacecraft; they build it, reconfigure it and do nearly everything else in the way of manufacturing and upkeep.

“You can basically flat-pack all the parts like furniture stores do and send them into space,” Cheung explains, adding that such a method removes the constraints imposed by having to launch fully built structures into space, as had been done with the ISS modules. By his reckoning, robots, sent along with the materials, would first build other robots, forming a small army that would then be able to work together in constructing whatever the blueprint dictates. Cheung says, “They can snap these panels together like LEGOs into an effectively infinite number of structures.”

While the concept sounds ahead of its time, Cheung says the technology for all of the pieces of the system are readily available, and to demonstrate that, he has built a proof-of-concept prototype called the Modular Rapidly Manufactured Small Spacecraft, or MRMSS. It’s a nanosatellite assembled with a collection of panels that can talk to each other and distribute power. One panel has a research payload attached to it: a science experiment out of MIT that will test functional electronic components. The spacecraft is expected to launch on a sounding rocket this year to show that all the equipment works in space. “We also want to show that such a spacecraft can survive launch, even though in the long term, the idea is that these things would be manufactured in orbit, because many of the manufacturing benefits still apply to premade spacecraft,” Cheung says.

In the more distant future, he envisions robots mining for raw minerals, which would then be used to manufacture components in order to build more spacecraft or even a spaceport. Cheung notes, “We’ve seen that we’re capable of landing on a comet, so the idea isn’t at all far-fetched.”

LaNetra Tate, principal technologist for the Space Technology Mission Directorate, is equally excited by the prospect. “These digital materials have the potential to revolutionize not only how we get to space, but also what we’ll be able to do once we get there,” she says, “and that’s why NASA is investing in this technology.”