MIT researchers 3D-printed RPAs for orbiting satellites. These operate similarly to expensive semiconductor sensors. (Image Credit: MIT)
MIT researchers developed 3D-printed plasma sensors, also called retarding potential analyzers (RPAs) for satellites. RPAs are responsible for measuring the atmosphere's chemical composition and ion energy distribution. The 3D-printed sensors performed similarly to top-of-the-line costly semiconductor plasma sensors that undergo a fabrication process for weeks at a time. In comparison, these 3D-printed sensors can be made in just a few days for tens of dollars, which means they could have Cubesats applications.
The team fabricated these RPAs with a glass-ceramic material, more durable compared to silicon and thin-film coatings. This process allowed them to develop uniquely shaped sensors that can handle temperature variations a spacecraft experiences in low Earth orbit.
“Additive manufacturing can make a big difference in the future of space hardware. Some people think that when you 3D-print something, you have to concede less performance. But we’ve shown that is not always the case. Sometimes there is nothing to trade off,” says Luis Fernando Velásquez-García, senior author of the paper.
Ceramics are usually 3D-printed via lasers targeting ceramic powder, fusing it into varying shapes. However, this results in a coarse material while generating weak points from high laser heat. So the team applied vat polymerization, a process that fabricates a 3D structure layer-by-layer via submerging it in Vitrolite. The ultraviolet light then cures the material after adding each layer, submerging the platform in the vat again. One layer measures just 100 microns thick, making it possible to create complex, smooth, pore-free ceramic shapes.
Objects in a design file for digital manufacturing can be quite complicated. So the precise process allowed the researchers to produce laser-cut meshes featuring unique shapes, perfectly aligning the holes as they were placed inside the RPA housing. In effect, more ions can pass through for higher-resolution measurements.
(Image Credit: MIT)
The team was able to prototype four unique designs thanks to the quick and inexpensive fabrication process. One design effectively captured and measured varying plasmas, similar to those satellites detect in orbit. Another was ideal for detecting ultra-dense and cold plasmas, which rely on ultraprecise semiconductor devices for measurements.
Overall, the tech could lead to 3D-printed sensors for fusion energy research or supersonic flight. The quick process can also prompt additional satellite and spacecraft design innovations. “If you want to innovate, you need to be able to fail and afford the risk. Additive manufacturing is a very different way to make space hardware. I can make space hardware and if it fails, it doesn’t matter because I can make a new version very quickly and inexpensively, and really iterate on the design. It is an ideal sandbox for researchers,” Velásquez-García says.
The team wants to improve the fabrication process even though they feel pleased with the results. Making the layers or pixel size in glass-ceramic vat polymerization thinner could lead to more precise, complex hardware. Additionally, fully additively fabricating the sensors makes them compatible with in-space manufacturing. The researchers also want to use AI for sensor design optimization to reduce their mass and make them structurally stable.
Have a story tip? Message me at: http://twitter.com/Cabe_Atwell