Lucas Erich, a second-year materials PhD student at UC Santa Barbara, has received a prestigious NASA Space Technology Graduate Research Opportunities (NSTGRO) Fellowship. Sponsored by NASA’s Space Technology Mission Directorate, the NSTGRO program supports researchers pursuing ideas that show significant potential to contribute to the agency’s goal of creating innovative space technologies.
 
“I am extremely excited and grateful,” said Erich, who earned his bachelor’s degree in materials science and engineering from Penn State University. “I’ve been fascinated by space for a while, so I feel fortunate to receive an opportunity from NASA to merge my passions for powder metallurgy and nuclear propulsion with my interest in space.” 

As an NSTGRO Fellow, Erich will receive up to $84,000 annually to cover his stipend, tuition, fees, travel, and health insurance for up to four years, and to pursue innovative, space-technology research at UCSB with his advisor, Daniel Oropeza, an assistant professor in UCSB’s Materials Department. He will also complete internships every summer at a NASA Center, where he will be matched with a NASA Subject Matter Expert who will serve as his research collaborator and act as a conduit into the larger technical community.

“Lucas is an incredibly intelligent and passionate student,” said Oropeza, who received a NASA Space Technology Research Fellowship himself when he was a graduate student at Massachusetts Institute of Technology in 2017. “This fellowship gives him the chance to work on exactly what he wants to do, complete summer rotations at up to four different NASA Centers, and develop deep connections at NASA. It’s a unique, amazing, and well-deserved opportunity.”

Erich’s research project is related to NASA’s pursuit of nuclear thermal and nuclear electric propulsion rocket-engine systems, technologies that draw energy from nuclear fission instead of traditional chemical reactions. In a nuclear thermal propulsion system, a fission reactor generates extremely high temperatures. The engine transfers the heat produced by the reactor to a liquid propellant, which is then converted to a gas and exhausted to propel the spacecraft. In nuclear electric propulsion systems, the energy produced from the reactor is converted to electricity by means of a steam turbine and used to generate a high voltage across two electrodes. This causes emission of electrons from the cathode which ionize a liquid propellant as it is ejected out the back of a thruster as a plasma. Nuclear rockets can be three or more times more efficient than conventional chemical propulsion spacecrafts and allow for faster transit times. NASA sees nuclear propulsion as a way to make a manned mission to Mars possible.  

“I think of the technology as miles to the gallon for your car,” explains Erich. “Nuclear propulsion would be like an electric or hybrid car, whereas chemical propulsion is like a diesel truck or muscle car.”

The main challenge to nuclear propulsion is finding materials that can withstand the intense reactor temperatures that are key to a nuclear rocket’s efficiency. Materials in direct contact with the reactor fuel and in sections of the thrusters must be able to survive temperatures above 4,500 degrees Fahrenheit. 

“The big issue with refractory metal alloys, or high-temperature metals, that are 3D printed is that they crack, which is not good,” said Erich, who previously worked at a powdered-metal plant and the Naval Nuclear Laboratory. “The goal in my project is to study metal powders for printing that could be used in space nuclear propulsion system components.”

Erich will use a key instrument in the Oropeza lab, the Amazemet rePowder, an ultrasonic atomization unit capable of processing metallic elements and metal alloys having melting points of up to 6300 degrees Fahrenheit. Lab members use the equipment to fabricate their own metal powders.

“During ultrasonic atomization, you melt a metal rod, then you vibrate the molten metal at extremely high frequencies,” explained Erich. “The tiny droplets expelled in the process then solidify into powder that can be printed.”

3D printing, referred to as additive manufacturing, offers a level of customization that traditional manufacturing methods cannot match. Although slower than other manufacturing techniques, it allows for the creation of complex geometries and structures, rapid prototyping, and cost reduction. 3D printing metal involves spreading a layer of powder over an area, then melting the layer with a laser to obtain the desired geometry. That two-step process is repeated continuously, creating layer upon layer, until the material becomes thick enough and solid. Erich says that he is thrilled to be working on a process that has the potential to revolutionize the next era of space travel. 

“I’m not going to be printing rocket nozzles for NASA during my PhD, but if I can develop metal powders for printing that demonstrate properties that prompt future development by NASA, that would be great,” said Erich. “I can’t wait to get started, and I am grateful for the guidance and support of Professor Oropeza; without him, this probably wouldn’t have been possible. I realize how very few graduate students are able to immerse themselves in the research opportunities and expertise at NASA.”