Could Future Mars Settlers Print Their Own Tools?

If humans one day settle Mars, they will need tools and parts to build structures on the planet. Carrying heavy, bulky supplies 34 million miles from Earth would be impractical. A better plan, says Zane Mebruer, a recent graduate of the University of Arkansas, would be 3D printing items on the Red Planet. His new research, completed while he was an honors undergraduate in mechanical engineering at the U of A, suggests it may be possible. 

The research, which Mebruer completed under the direction of Wan Shou, assistant professor of mechanical engineering, was published in the Journal of Manufacturing and Materials Processing. 

Typically, 3D printing of metal is done in a chamber filled with argon, a non-toxic gas that prevents oxidation. Mebruer wanted to see if 3D printing of metal could be done successfully in a carbon dioxide atmosphere, which makes up 95% of Mars atmosphere. If it could, argon would not have to be transported to or manufactured on Mars. 

Mebruer's research used laser beam powder bed fusion, often abbreviated as PBF-LB. In this method of 3D printing of metal, a metal powder is spread in a single layer across a plate. A laser fuses the powder into a solid layer. The plate lowers, another layer of powder is applied, and the laser fuses it into the next layer of the object. 

The process is efficient. The unused metal from each layer can be collected and recycled. The metal, however, can quickly oxidize during the production process. Unlike rust on the outside of a metal object, oxidation that occurs during additive manufacturing can weaken the internal structure of the part. 

"The cohesion between layers is going to be a lot worse. The material strength is going to be impacted," Mebruer said. 

In the experiment, simple, single-layer metal lines were printed in atmospheres of argon, carbon dioxide and the ambient air. The results were examined at the microscopic level for imperfections and how nearly the single-layer parts achieved a uniform, flat surface. While printing in argon produced the best results, the parts printed in CO2 showed promise and were superior to those produced in the ambient atmosphere. 

"It's a proof of concept," said Shou, who helped Mebruer conceptualize the work and oversaw the research in his lab. 

The work is a small step toward human settlement of Mars. For Mebruer, the work he completed as a U of A undergraduate — and getting the results published in a peer-reviewed journal — was a giant leap in his career. 

Mebruer is now a doctoral student in mechanical engineering at the Georgia Institute of Technology. When he interviewed for the program, his current advisor wanted to know about the work and his undergraduate research at U of A. 

"Almost all we talked about was this research project. He was impressed. He sent an offer pretty quickly after that," Mebruer said.