Researchers from the Department of Energy’s Oak Ridge National Laboratory (ORNL) and NASA have 3D printed a wheel similar to that of NASA’s robotic lunar rover – showcasing the technology’s potential for creating specialized components vital for space exploration.
The 3D printed wheel was based on the design used in the Volatiles Investigating Polar Exploration Rover (VIPER), a robot that NASA intends to deploy in 2024 to map ice and other resources at the moon’s south pole. VIPER’s mission will help scientists understand the origin, distribution, and potential harvesting capacity of the moon’s water to support human habitation.
Although the wheel prototype isn’t destined for the moon, it matches the design criteria of NASA’s VIPER wheels. Further tests will evaluate this design and its fabrication method for use in future space missions.
Additive manufacturing, which can cut down energy consumption, material wastage, and lead time, also supports intricate designs and allows customization of material properties. The DOE’s Manufacturing Demonstration Facility (MDF), having spearheaded such technology for over a decade, developed the wheel prototype in 2022, using a unique 3D printer. This printer, large enough to fit a person, deploys two synchronized lasers and a spinning build plate to selectively melt metal powder into the desired structure. Unlike standard metal powder bed systems, this one works continuously, with the processes happening simultaneously.
“This dramatically increases the production rate with the same amount of laser power,” said Peter Wang, who leads MDF development of new laser powder bed fusion systems, adding that deposition occurs 50% faster. “We’re only scratching the surface of what the system can do. I really think this is going to be the future of laser powder bed printing, especially at large scale and in mass production.” Wang and project team members recently published a study analyzing the scalability of the technology for printing components like electric motors.
Wang emphasized that the printer’s uniqueness is matched by the team’s expertise in automation and machine control. The researchers utilized ORNL-developed software to slice the wheel’s design into vertical segments – evenly distributing the work between the two lasers – resulting in an efficient production rate. This approach leverages a computational technique recently proposed for patenting.
The prototype wheel, composed of a nickel-based alloy, measures 8 inches in width and 20 inches in diameter – larger than parts usually printed with metal powder systems. Using 3D printing, the team achieved intricate rim designs without extra cost or fabrication challenges. In contrast, VIPER’s wheels, set to roll on the moon soon, underwent numerous manufacturing and assembly procedures – making them complex and labor-intensive.
“A lot of these wheel features were put in just to highlight what you can do with additive manufacturing,” said Richard Hagen, a mechanical design engineer for NASA and additive manufacturing lab manager at NASA’s Johnson Space Center, in Houston. “It lets you easily implement design features that are hard to implement with traditional tooling or even a traditionally machined part.”
If the 3D printed wheel matches the robustness of traditionally built ones, future rovers might opt for this single-printed wheel rim, which took only 40 hours to produce at ORNL. The 3D printing process introduced features like angled sidewalls, domed shapes, and wavy treads – enhancing wheel stiffness.
However, there are limitations. The printer works only with specific materials – resulting in the 3D printed wheel being 50% heavier than VIPER’s aluminum one when printed with similar thickness.
NASA intends to test this 3D printed wheel’s performance on a rover, either at NASA’s Johnson Space Center or a specialized testing facility – evaluating various performance metrics.
Crewed research stations placed on the moon as part of the agency’s Artemis Program will need off-planet manufacturing capability. “Being able to build parts in space for repairs will be important, because you just can’t take enough spares,” said Hagen. “Powder, pellets, or filament for printing are a lot easier to pack and would allow for more flexibility.”
“Additive manufacturing offers the flexibility that if you have the feedstock, you could make any replacement part you need, whether in space or on Earth,” said Brian Gibson, the researcher who led the rover wheel project for ORNL. This is a reason additive manufacturing has generated significant interest for a range of replacement needs, from rapidly manufactured tooling to hard-to-source castings and forgings. For space exploration and habitation, 3D printers could eventually use local material from the moon or Mars as a feedstock.