During a mission, satellites constantly battle Earth’s gravity to stay aloft and maintain orbit. It’s no easy feat and usually requires expensive, bulky propellant tanks to generate sufficient thrust, which are too large and overdesigned for the needs of a small satellite.
A promising alternative to standard chemical propulsion is vacuum arc thrusters, a micro-propulsion system that creates plasma to generate thrust and is compact enough to fit inside small satellites, which are increasingly being researched to enhance mission capabilities while reducing costs. However, these thrusters remain largely experimental as they must endure millions of firings–or pulses– during a mission to maintain orbital stability without sacrificing performance.
How do we design and operate a vacuum arc thruster to reliably deliver millions of pulses without losing performance?
This is the question that first-year PhD student Guru Sankar Duppada, M.S. ‘24, set out to answer as he began his doctoral research in the Micropropulsion and Nanotechnology Laboratory, led by the A. James Clark Professor in Engineering, Michael Keidar. Now, less than a year later, he’s developed a thruster that can reach 15 million pulses–moving them one step closer to real missions.
“Demonstrating 15 million pulses experimentally is a big milestone because lifetime has always been the toughest challenge for micro-propulsion systems, and 15 million is just the start,” said Duppada. “It’s one thing to make a thruster fire a few times in the lab, but in space, a satellite might need millions of firings over its mission for tasks like orbit corrections or formation flying.”
To reach this milestone, Duppada explored how the thruster behaves under different conditions, changing materials, electrode shapes, and how power is delivered to understand what works versus what breaks down over time. The process wasn’t easy and required lots of trial and error and adjustments before he uncovered a setup that could sustain operation at this scale.
The biggest challenges Duppada faced were refining the power delivery system and preventing electrode erosion. His lab peers were a strong support system for him as he worked through these obstacles to ensure every pulse was consistent and reliable over long runs, and to optimize the system’s design to avoid pulses slowly wearing down the cathode.
“It hasn’t just been about running tests in the lab; it has been about problem-solving when things didn’t go as planned, learning from setbacks, and slowly building a system that could keep going where earlier designs would have failed. Hitting this milestone feels like proof that the long hours and constant adjustments are paying off,” Duppada said.
Demonstrating 15 million pulses experimentally proves that Duppada’s vacuum arc thruster can withstand the endurance a real mission demands. Being early in his doctoral program, this achievement is especially significant for Duppada as it proves the questions he’s chasing about making vacuum arc thrusters more reliable and long-lasting are not just theoretical but achievable in practice and can have real implications for future space missions.
Duppada shared that Keidar’s guidance also helped him see the long-term impact of his work, as Keidar’s ability to connect fundamental science and practical applications has influenced his research approach. This mindset encourages him to look at the thruster as more than just a lab experiment, but rather a system that can become flight hardware.
“It’s not just about proving a thruster can pulse millions of times; it’s about opening the door for small satellites to take on bigger, longer, and more ambitious missions,” Duppada stated.
By replacing traditional bulky setups, these simple, lightweight, scalable thrusters could reshape our thinking about propulsion for the next generation of small satellites, like CubeSats. They not only provide effective propulsion for tasks like orbit control, constellation management, and safe de-orbiting but also open up new mission possibilities–all while reducing cost and complexity for satellite developers and without sacrificing mass or volume that could be used for payloads.
As Duppada continues his doctoral program, this milestone encourages him to continue developing his vacuum arc thruster. He will focus on improving its propellant utilization efficiency, refining the electrode design to extend its lifetime, and testing ways to integrate the system into CubeSat platforms.
“The ultimate goal is to take what we’ve proven in the lab and move closer to a version that can be commercialized and flown in space. For me, this project is about building the bridge between research and real missions, and that’s the path I want to keep moving forward on,” said Duppada.