As soon as the end of September, Jason Budinoff, an aerospace engineer at NASA, says his team will have completed the first imaging telescopes ever assembled almost entirely from 3D printed and manufactured components.
"As far as I know, we're the first to attempt to build an entire instrument with 3D printing," Budinoff says of his work for NASA's Goddard Space Flight Center in Greenbelt, Maryland.
The NASA experiments involve small space cameras, some of them designed to fit inside a four-inch CubeSat, which will put into service once they've undergone vacuum and vibrational testing.
The cameras and telescopes will be constructed from powdered aluminum and titanium via sintering and Budinoff says the advantage of creating parts using AM is that the printer can produce several parts in a single run. He added that a telescope made using AM techniques could theoretically contain five to 10 times fewer parts than a similar device made from solid metal using reductive methods, and that the process results in a more stable instrument.
While conventional manufacturing techniques will still be used to make the necessary mirrors and lenses, Budinoff says he's developing techniques to make mirrors from aluminum powder.
The project was funded by the Internal Research and Development (IRAD) program at Goddard, and Budinoff says he's also currently assembling a 350-millimeter, dual-channel telescope as part of the research for the Pathfinder Project.
"This is a pathfinder. When we build telescopes for science instruments, it usually involves hundreds of pieces. These components are complex and very expensive to build. But with 3D printing, we can reduce the overall number of parts and make them with nearly arbitrary geometries," Budinoff says. "We're not limited by traditional mill and lathe fabrication operations."
He calls the project a proof-of-concept of sorts, but sees applications for the techniques in the not too distant future.
"I basically want to show that additive machined instruments can fly. We'll have mitigated the risk, and when future program managers ask, 'Can we use this technology?' we can say, 'Yes, we already have qualified it,'" Budinoff says.
The plan also calls for the creation of a 3D-fabricated unpolished mirror blank which will be placed inside a pressure chamber filled with inert gas. The gas pressure will be increased to 15,000 psi within a heated chamber to "squeeze" the mirror to reduce the surface porosity, a technique referred to as "hot isostatic pressing."
"We think this, combined with the deposition of a thin layer of aluminum on the surface and Goddard-developed aluminum stabilizing heat treatments, will enable 3D printed metal mirrors," says Budinoff of the concept.
Upcoming experiments also include printing instruments from 'Invar' alloy. Invar is a an iron-nickel alloy which offers extreme dimensional stability through a wide range of temperature variations and that makes it ideal for building stable, lightweight frameworks to support telescopes and other instrumentation.
"Anyone who builds optical instruments will benefit from what we're learning here. I think we can demonstrate an order-of-magnitude reduction in cost and time with 3D printing," Budinoff adds.