Bad news if you want to move to the Moon or Mars – accommodation is a bit hard to come by.
Bad news if you want to move to the Moon or Mars: accommodation is a bit hard to come by. Fortunately, NASA (as always) is thinking ahead and has just unveiled a self-building robotic structure that could be a crucial part of off-planet living.
Published today in Science Robotics, the NASA Ames Research Center paper describes the creation and testing of what they call "self-programmable mechanical metamaterials," which is a very precise way of describing a building that constructs itself. The inevitable acronym for it is "Adaptive Robotic Materials Assembly Digital Assemblers for Reconfigurable Automated Missions," or ARMADAS.
"We think this kind of building technology could serve many very general applications," said first author Christine Gregg to TechCrunch. "In the short term, the robust autonomy and lightweight structures of our approach strongly benefit applications in austere environments, such as the lunar surface or space. This includes constructing communication towers and shelters on the lunar surface that will be necessary before astronauts arrive, as well as in-orbit structures like arms and antennas."
The basic idea of the self-building structure relies on a smart synergy between the building material - cuboctahedral frames called voxels - and the two types of robots that assemble them.
One type of robot walks along the surface with two legs, apparently inspired by kinetic transport molecules in our biology, carrying a voxel like a backpack. When put in position, a fixing robot that lives in the frame itself like a worm crawls over and tightens the reversible attachment points. Neither needs a powerful sensing system, and the way they work means high precision isn't required.
You can see a couple of walkers and a fixing worm in most of the images in this post. And here's a transport walker delivering a voxel to a positioning walker, with the fixing robot lurking below ready to slide and lock the frame into place.
The shape of the pieces allows them to be joined at different angles while maintaining good structural integrity. You probably wouldn't want to keep rocks off with a dome made of these things, but they'd be excellent as a base to which you add insulation and sealing to make a habitat.
"We think this kind of construction is particularly suited for very long-duration and/or very large infrastructures, including habitats, instrumentation, or any other infrastructure in orbit or on the surface of the moon (service towers, landing structures for vehicles)," said co-author Kenneth Cheung. "For us, the structures and all of the robotic systems are resources that can be optimized over space and time. It seems like there will always be situations where the best thing is to leave just the structure in place (and maybe visit it periodically with a robot), so we started from there."
The pieces themselves might also be built on site, Gregg noted:
"The voxels can be made with many different materials and manufacturing processes. Ultimately, for space applications, we'd like to make voxels out of materials that we find in situ on the moon or other planetary bodies."
Of course, these videos of the robots at work are heavily sped up, but unlike work in a factory or on a sidewalk, speed isn't necessarily essential when it comes to building things in space or on another planet.
"Our robots can work faster than shown in this article, but we didn't find it essential to achieve the primary goals," Cheung said. "Basically, the way to make this system work faster is to use more robots. The general strategy for scalability (in speed and size) is to be able to push complexity to the algorithms, for planning and scheduling, as well as fault detection and repair during execution."
The lab's robots took 256 voxels and assembled them into a habitable structure over a total of 4.2 days' worth of work. Here's how it started (again, far from real time):
If we were to send them ahead to Mars or the Moon a year before a crew arrived, they could build a dozen or so double-sized structures in that time. Or they could attach the necessary plates on the outside later and seal them - that's somewhat beyond the scope of the paper published today, but it's a clear next step.
While the robots have cables providing them with power in this lab environment, they're designed with battery or on-site power use in mind. The fixing robot is already battery-powered, and researchers are looking at ways to keep the walkers charged between operations or even during them.
"We think the robots could be recharged autonomously at charging stations or even through wireless power. As you mentioned, power could also be routed through the structure itself, which might be useful for equipping the structure and powering the robots," Gregg said.
Versions of the robot have already been sent to space and have worked in microgravity, so there are no concerns on that front. And there's nothing in principle stopping them from working in non-Earth gravity like that of the Moon. That said, this is just the beginning — revealing that axes and nails exist. There's more on the potential and concept illustrations of what they could build in this NASA news post.
"Future versions of our lab environment robots will be faster and more reliable, based on lessons learned with the early versions. We are very interested in understanding how different types of building blocks can be integrated into structures to provide functional outfitting," Gregg said.
Research will also continue on structures that employ swarms of robots, not just a handful; a rough shelter might take two transport walkers four days, but something 10 times larger might take 100 times longer. But many hands — especially robotic ones — make light work.
