3D printed MOXIE experiment makes oxygen on Mars
We’ve written extensively about the 3D printed parts on NASA’s incredibly successful Perseverance Mars mission, now we are seeing what those functional parts actually do and it’s not a minor detail: the MOXIE system, which was produced internally via metal L-PBF technology at JPL, was able to transform the carbon dioxide in Mars’ atmosphere into Oxygen.
According to Douglas Hofmann, Principal at NASA Jet Propulsion Laboratory/California Institute of Technology, this experiment was a pathfinder for larger-scale O2 generation on future missions. “The exciting part for our section is that the demonstration was enabled by several 3D printed Inconel 625 parts in the heater assembly,” he explained. “These were printed by Andre Pate and his team on an EOS M290. It represents our first home-built metal parts flown in space. And, if I’m not mistaken, this is one of the first demonstrations of ISRU (In-Situ Resource Utilization) on another planet.”
Perseverance’s six other 3D printed parts can be found in an instrument called the Mars Oxygen In-Situ Resource Utilization Experiment, or MOXIE. This device will test technology that, in the future, could produce industrial quantities of oxygen to create rocket propellant on Mars, helping astronauts launch back to Earth.
To create oxygen, MOXIE heats Martian air up to nearly 1,500 degrees Fahrenheit (800 degrees Celsius). Within the device are six heat exchangers – palm-size nickel-alloy plates that protect key parts of the instrument from the effects of high temperatures. While a conventionally machined heat exchanger would need to be made out of two parts and welded together, MOXIE’s were each 3D printed as a single piece at nearby Caltech, which manages JPL for NASA.
“These […] superalloys […] maintain their strength even at very high temperatures,” said at the time of launch Samad Firdosy, a material engineer at JPL who helped develop the heat exchangers. “Superalloys are typically found in jet engines or power-generating turbines. They’re really good at resisting corrosion, even while really hot.”
Although the new manufacturing process offers convenience, each layer of alloy that the printer lays down can form pores or cracks that can weaken the material. To avoid this, the plates were treated in a hot isostatic press – a gas crusher – that heats the material to over 1,832 degrees Fahrenheit (1,000 degrees Celsius) and adds intense pressure evenly around the part. Then, engineers used microscopes and lots of mechanical testing to check the microstructure of the exchangers and ensure they were suitable for spaceflight.
“I really love microstructures,” Firdosy said. “For me to see that kind of detail as the material is printed, and how it evolves to make this functional part that’s flying to Mars – that’s very cool.”