A team of MIT engineers is designing a kit of universal robotic parts that an astronaut could easily mix and match to rapidly configure different robot ‘species’ to fit various missions on the moon. Once a mission is completed, the robots can be disassembled and their parts used to configure new robots to meet a different task, thusavoiding a situation where the moon base becomes overrun by a zoo of machines, each with its own unique parts and protocols.
The team calls the system WORMS: Walking Oligomeric Robotic Mobility System. Its parts include worm-inspired robotic limbs that an astronaut can easily snap onto a base and that work together as a walking robot. Depending on the mission, parts can be configured to build, for instance, large ‘pack’ bots capable of carrying heavy solar panels up a hill. The same parts could be reconfigured into six-legged spider bots that can be lowered into a lava tube to drill for frozen water.
‘You could imagine a shed on the Moon with shelves of worms,’ said team leader George Lordos, a PhD candidate and graduate instructor in MIT’s Department of Aeronautics and Astronautics, in reference to the independent, articulated robots that carry their own motors, sensors, computer and battery. ‘Astronauts could go into the shed, pick the worms they need, along with the right shoes, body, sensors and tools, and they could snap everything together, then disassemble it to make a new one. The design is flexible, sustainable and cost-effective.’
WORMS was conceived in 2022 as an answer to NASA’s Breakthrough, Innovative and Game-changing (BIG) Idea Challenge – an annual competition for university students to design, develop and demonstrate a game-changing idea. In 2022, NASA challenged students to develop robotic systems that can move across extreme terrain without the use of wheels.
A team from MIT’s Space Resources Workshop took up the challenge, aiming specifically for a lunar robot design that could navigate the extreme terrain of the Moon’s South Pole – a landscape that is marked by thick, fluffy dust, steep, rocky slopes and deep lava tubes. The environment also hosts ‘permanently shadowed’ regions that could contain frozen water, which, if accessible, would be essential for sustaining astronauts.
As they mulled over ways to navigate the Moon’s polar terrain, the students took inspiration from animals. In their initial brainstorming, they noted that certain animals could conceptually be suited to certain missions: a spider could drop down and explore a lava tube, a line of elephants could carry heavy equipment while supporting each other down a steep slope, and a goat, tethered to an ox, could help lead the larger animal up the side of a hill as it transports an array of solar panels.
‘As we were thinking of these animal inspirations, we realised that one of the simplest animals, the worm, makes similar movements as an arm, or a leg, or a backbone, or a tail,’ said deputy team leader and graduate student Michael Brown. ‘And then the lightbulb went off – we could build all of these animal-inspired robots using worm-like appendages.’
‘Our idea was that, with just a few parts, combined in different ways, you could mix and match and get all these different robots,’ said undergraduate student Brooke Bensche.
The system’s main parts include the appendage, or worm, which can be attached to a body, or chassis, via a ‘universal interface block’ that snaps the two parts together through a twist-and-lock mechanism. The parts can be disconnected with a small tool that releases the block’s spring-loaded pins. Appendages and bodies can also snap into accessories such as a ‘shoe’, which the team engineered in the shape of a wok, and a LiDAR system that can map the surroundings to help a robot navigate.
‘In future iterations we hope to add more snap-on sensors and tools, such as winches, balance sensors and drills,’ said undergraduate student Jacob Rodriguez.
The team developed software that can be tailored to coordinate multiple appendages. As a proof of concept, the team built a six-legged robot about the size of a go-cart. In the lab, they showed that once assembled, the robot’s independent limbs worked to walk over level ground. The team also showed that they could quickly assemble and disassemble the robot in the field, on a desert site in California.
In its first generation, each WORMS appendage measures about one metre long and weighs about nine kilograms. In the Moon’s gravity, which is about one-sixth that of Earth’s, each limb would weigh about 1.4 kilograms, which an astronaut could easily handle to build or disassemble a robot in the field. The team has planned out the specs for a larger generation with longer and slightly heavier appendages. These bigger parts could be snapped together to build ‘pack’ bots, capable of transporting heavy payloads.
‘There are many buzz words that are used to describe effective systems for future space exploration: modular, reconfigurable, adaptable, flexible, cross-cutting, et cetera,’ said Kevin Kempton, an engineer at NASA’s Langley Research Center who served as a judge for the 2022 BIG Idea Challenge. ‘The MIT WORMS concept incorporates all these qualities and more.’