WHY THIS MATTERS IN BRIEF
There are no spare parts in the deep universe to repair broken robots with, but there’s plenty of ice …
“It was right around dawn on the frigid world of Enceladus, the sixth-largest moon of Saturn, when the ice robots began to stir. Receiving their marching orders from half a billion miles away, the frozen rovers twitched and hummed and cracked in temperatures hundreds of degrees below freezing point. These were not robots that had simply been covered in a thin layer of ice, like a car that’s been left out on a cold winter’s night. Instead, they were hewn almost exclusively out of great chunks of ice; giant, frozen sculptures that moved and probed the surface of one of the solar system’s most tantalizingly unexplored worlds, animated by the search for life.”
A dramatic, science fiction way to open an article about a new concept for building robots? Quite possibly. But if researchers from the GRASP Lab at the University of Pennsylvania in Philadelphia are correct, this may not remain science fiction for too much longer – just as crystal robots, which used to be science fiction have now also become science fact.
Remote-controlled rovers have been used as part of space exploration going back decades. NASA included Lunar Roving Vehicles in three of its Apollo missions, starting with Apollo 15, which landed on the moon in July 1971. The Mars Exploration Rover Opportunity was in active service on red planet for a decade-and-a-half, from 2004 until early 2019.
But while these kinds of exploratory robots are built to be robust, there’s a limit to their survivability. The car-sized Curiosity picked up some severe tire damage while making its way across the Martian surface, peppered as it is with sharp rocks.
“If there were mechanics on Mars, NASA may have taken the Curiosity rover into the shop by now,” opined Space.com.
Meanwhile, the long-running Opportunity mission went dark for good following an intense dust storm in 2018. This obscured its solar panels, leaving it to run out of battery. NASA clung on for another year before finally admitting the mission had come to an early, unceremonious end. Its identical twin, Spirit, was previously pronounced dead in 2011 after becoming stuck in Martian sand.
This is a problem because, while the robots may cost millions to make they’re at the center of missions that can cost in the billions of dollars. If they suffer damage or technical misfortune, no matter if it’s just damaged tires or dust on the solar panels, it means that all the effort up until then — the construction process, the rocket launch, the landing — is for naught. It’s like having to abandon your new supercar for good at the side of the road because you’ve suffered a flat.
That’s why researchers want to build modular robots that can repair or otherwise augment themselves in scenarios where shipping in a replacement simply isn’t feasible from a cost and logistics perspective. They could even, in theory, build replicas of themselves or other robots entirely. To do this, they would utilize local materials — like, say, ice on an ice moon. This is where the GRASP Lab’s ice robot IceBot project comes into the picture.
“IceBot is a first-of-its-kind robot made from ice,” said Devin Carroll, lead author on the project. “[In our new work, we present] a proof-of-concept, two-wheeled robot to show the feasibility of building robots from ice. Our intent with this technology is to advance the self-repair, self-reconfiguration, and self-replication capabilities of exploration robots. In making a robot like this, we are one step closer to a true self-replicating system – one that can use materials from the local environment to repair, augment, and replicate itself.”
Carroll and collaborator Mark Yim began their project by exploring ways to build robots using found materials. This would help expand the robustness of such systems operating in distant or hostile locations by allowing them to recycle and reuse equipment that was found in the local environment.
“We chose to use ice as our primary building material because of its design flexibility,” Carroll continued. “Interest in icy environments is relatively high due to research relating to climate change, as well as extra-terrestrial exploration. Using ice as a building material allows us to repair the robot on the fly, extending the total operational life of the system as it collects data in these remote and harsh environments.”
This wouldn’t have to be somewhere as far-flung as Enceladus, of course. It could be somewhere closer to home, like Antarctica, where remote-controlled robots can also be useful for conducting research. In either case, when the elements begin to wear away or break down, new ones could be created as replacements, much in the same way that biological bodies can regenerate.
The researchers have so far built a proof-of-concept demo robot that’s able to operate for periods in both room-temperature and subzero environments, traveling over hard rubber surfaces and climbing icy, inclined ramps. Along with the ice body, it utilizes an Arduino Micro microcontroller, Bluetooth module, and a few other manufactured components.
It’s still early days, however. Proving that a robot with a body made out of ice can function is one thing. But a big, and very difficult, part of the project — manufacturing the ice components autonomously — has yet to be demonstrated. The researchers are considering multiple approaches, including 3D printing, moulding, and machining, each of which has its pros and cons.
“Our immediate goal is to design a module joint that will allow us to automate the assembly process,” Carroll said. “We will be able use automation to join our actuators with the ice rather than building the robot by hand. In conjunction with this, we are developing an end effector to manipulate blocks of ice without permanently deforming them, as would happen through the use of traditional fasteners like screws.”
He continued: “An interesting design challenge we must solve with both of these directions is ensuring that we maximize the connection strength while the amount of energy used to join the components with the ice is minimized. In remote environments, energy is a valued commodity. Systems like IceBot will only be effective if we consider energy usage when designing them.”
Projects like this are only going to become more important. In the pioneer tradition, being able to utilize new, local materials for everything from growing food and fuel to building habitats is a crucial part of surviving — and thriving — in space. Robots that don’t have to be shipped, at vast expense, from Earth to wherever they need to go is one more piece of the puzzle.
A paper describing the IceBot project, titled “Robots Made From Ice: An Analysis of Manufacturing Techniques,” was recently presented at IROS.