On February 24, 2026, engineers at NASA’s Jet Propulsion Laboratory fired up a prototype lithium-fed magnetoplasmadynamic (MPD) thruster in Southern California, achieving 120 kilowatts of power during five separate vacuum chamber runs. This milestone marks a significant leap for deep-space propulsion, delivering more than 25 times the power of current systems like those pushing the Psyche spacecraft toward a metal-rich asteroid.
The 120-Kilowatt Milestone and Thermal Realities
Deep inside a specialized 26-foot-long vacuum chamber at JPL’s Electric Propulsion Lab, the prototype’s tungsten electrode glowed white-hot, exceeding 5,000 degrees Fahrenheit. Researchers observed a vibrant red plume emerging from the nozzle-shaped outer electrode, confirming stable operation under extreme conditions. This setup utilized a unique condensable metal propellant facility engineered specifically to handle metal vapor tests scaling up to megawatt levels.
Developing this hardware took two and a half years of collaborative effort led by JPL alongside Princeton University and NASA’s Glenn Research Center. Senior research scientist James Polk observed the test firsthand, calling it a huge moment after years of preparation and noting that the engineering team successfully met their targeted power levels. NASA Administrator Jared Isaacman emphasized the broader implications of the trial, stating that it represented real progress toward sending an American astronaut to set foot on the Red Planet.
Electromagnetic Plasma Versus Electrostatic Ion Engines
Understanding the architectural jump requires looking closely at how different propulsion systems accelerate mass. Magnetoplasmadynamic systems differ fundamentally from traditional electrostatic ion engines. While ion engines ionize and electrically accelerate inert gases like xenon, MPD systems use high currents and magnetic fields to electromagnetically propel lithium plasma.
Lithium metal vapor serves as the propellant in this new prototype, offering distinct efficiency advantages over the xenon used in conventional solar-powered systems. Electric propulsion overall consumes up to 90% less propellant than chemical rockets, building up speed gradually over long operational durations. Although researchers have studied lithium MPD technology since the 1960s, it has never flown on an operational space mission.
| Feature | Lithium MPD Prototype | Psyche Thrusters |
|---|---|---|
| Power Level | Up to 120 kW | ~4.5 kW per thruster |
| Propellant | Lithium metal vapor | Xenon gas |
| Power Source | Nuclear (future) | Solar |
| Thrust Type | Electromagnetic plasma | Electrostatic ions |
To put this raw scale into perspective, NASA’s Psyche spacecraft currently relies on Hall-effect thrusters representing the pinnacle of active spaceflight electric propulsion. Those systems operate at around 4.5 kilowatts each, expelling charged atoms of xenon gas and creating a characteristic blue glow while providing up to 240 millinewtons of thrust—roughly the force of holding a single AA battery. Psyche carries seven 22-gallon tanks of xenon to sustain its journey toward the asteroid, powered by cross-shaped solar arrays that generate 21 kilowatts near Earth but drop sharply during transit.
The 120-kilowatt lithium prototype dwarfs those operational figures, delivering massive power density that could eventually enable heavier payloads and vastly reduced transit times for deep-space crews.
Scaling Toward Megawatt-Class Nuclear Systems
Funded under NASA’s Space Nuclear Propulsion project since 2020, this development effort targets megawatt-class systems tailored explicitly for human exploration. A crewed mission to Mars will likely demand between 2 and 4 megawatts of total power, supplied by clusters of MPD thrusters running continuously for over 23,000 hours.
Pairing these thrusters with space nuclear reactors will help overcome the severe limitations of solar power far from the Sun, slashing launch mass while maximizing capacity for human habitats and life support supplies. Severe heat management remains a primary hurdle given the extreme temperatures generated during extended operations. To conquer this, the JPL team plans to push individual thrusters even further, scaling targets up to 500 kilowatts and eventually 1 megawatt in upcoming trials.
