Page 45 - 2021cnc2-3web

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 kinds of nickel parts
are called superalloys because they maintain their strength even at very high temperatures,” said 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.”
he outer shell of PIXL, one of the instruments aboard NASA’s Perseverance Mars rover, includes several parts that were made of 3D-printed titanium. The inset shows the front half of the two-piece shell part it was finished.
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 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 material is printed, and how it evolves to make this functional part that’s flying to Mars – that’s very cool.”
More About the Mission
A key objective of Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith (broken rock and dust).
Subsequent missions, currently under consideration by NASA in cooperation with ESA (the European Space Agency), would send spacecraft to Mars to collect these cached samples from the surface and return them to
Earth for in-depth analysis.
The Mars 2020 mission is part of a larger program
that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with returning astronauts to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through NASA’s Artemis lunar exploration plans.
JPL, which is managed for NASA by Caltech in Pasadena, Southern California, built and manages operations of the Perseverance and Curiosity rovers.
CNC WEST February/March 2021
www.CNC-West.com 43
This X-ray image shows the inside of a 3D-printed part inside of Perseverance’s MOXIE instru- ment. Martian air will be carried inside the tiny channels in the center of this part, where they’ll be pre-heated. X-ray images like these are used to check for defects inside of parts; in this case, engineers checked to make sure the channels were free of 3D printing powder.