JPL Prototype Lithium MPD Thruster Reaches 120 kW in Ground Test

NASA’s Jet Propulsion Laboratory said a prototype lithium-fed electric thruster reached 120 kilowatts during a ground vacuum test on Feb. 24, a power level the agency says marks the highest-power electric-propulsion test yet conducted in the United States. The result is an early laboratory milestone, not a flight-ready engine for Mars missions.

JPL announced the test in an April 28 news release, later posted by NASA, framing it as a step toward much higher-power electric propulsion for deep-space travel. NASA has said that kind of technology could eventually support crewed Mars mission concepts, but the significance here is the jump in test power, not a demonstration that the system is ready for space.

The prototype is a lithium-fed magnetoplasmadynamic, or MPD, thruster, a type of electric propulsion that uses very high electrical currents and magnetic fields to accelerate plasma and generate thrust. The concept has been studied since the 1960s, but this kind of MPD thruster has not been used operationally on deep-space missions.

The Feb. 24 test took place at JPL’s Electric Propulsion Lab in the CoMeT vacuum facility, a 26-foot, water-cooled chamber built for high-power testing with metal-vapor propellants. During the initial test series, the team completed five ignition cycles. JPL said the thruster’s central tungsten electrode exceeded about 5,000 degrees Fahrenheit, or roughly 2,800 degrees Celsius, during those firings.

JPL and NASA said the 120-kilowatt result is more than 25 times the power of the electric thrusters now flying on NASA’s Psyche mission, which is using Hall-effect thrusters to travel to a metal-rich asteroid. That comparison helps explain why the test matters: current flight electric propulsion typically operates in the single- to low-kilowatt range per thruster, while NASA says future human Mars missions could require a total of 2 to 4 megawatts of electrical power and likely multiple MPD thrusters running for more than 23,000 hours.

The work is led by JPL, with collaborators at Princeton University and NASA’s Glenn Research Center in Ohio. Funding comes from NASA’s Space Nuclear Propulsion project, part of the agency’s Space Technology Mission Directorate.

Still, the biggest questions are unresolved. This thruster has not flown in space, and JPL and NASA have not publicly released detailed thrust, efficiency, erosion or lifetime data from the Feb. 24 test. Those are central measures for judging whether a high-power electric thruster can be scaled into something practical for long missions, where hardware would have to operate for thousands of hours without unacceptable wear.

For now, JPL is presenting the result as an opening benchmark rather than proof of mission readiness. “Designing and building these thrusters over the last couple of years has been a long lead-up to this first test,” James Polk, a senior research scientist at JPL, said in the release. “It’s a huge moment for us because we not only showed the thruster works, but we also hit the power levels we were targeting. And we know we have a good testbed to begin addressing the challenges to scaling up.”

The next goal, JPL said, is to push the technology much further, to between 500 kilowatts and 1 megawatt per thruster.