NASA JPL Fires Up 120-Kilowatt Lithium-Fed Magnetoplasmadynamic Thruster, a 25x Power Leap Over the Psyche Engines
On Feb. 24, a JPL-led team ran a lithium-vapor magnetoplasmadynamic thruster at 120 kilowatts inside the CoMeT vacuum chamber, more than 25 times the power of the electric engines on NASA's Psyche spacecraft.
Overview
On Feb. 24, engineers at NASA’s Jet Propulsion Laboratory in Southern California fired up a prototype electric thruster that runs on lithium metal vapor and reached power levels of up to 120 kilowatts, according to JPL. The agency disclosed the test results publicly in late April and early May, calling it the first time in years that an electromagnetic thruster of this design had operated at such power levels in the United States.
The device is a magnetoplasmadynamic, or MPD, thruster — a class of electric engine that uses high electrical currents interacting with a magnetic field to accelerate plasma. In this case, the plasma is made from lithium vapor, as ScienceDaily described, with the engine fueled by lithium vapor and driven by intense magnetic forces.
What We Know
The test took place inside JPL’s Electric Propulsion Lab, in the condensable metal propellant (CoMeT) vacuum facility, according to JPL’s release. SpaceWar reported that the chamber is a 26-foot-long, water-cooled vacuum vessel designed to handle metal-vapor propellants at up to megawatt-class power levels.
The 120-kilowatt figure is the headline result. NASA said that is over 25 times the power of the thrusters on Psyche, which is currently operating the highest-power electric thrusters of any NASA spacecraft. During five ignitions, the tungsten electrode at the thruster’s center glowed bright white, reaching over 5,000 degrees Fahrenheit (2,800 degrees Celsius), according to JPL.
James Polk, senior research scientist at JPL, framed the test as a milestone for the team. “Designing and building these thrusters over the last couple of years has been a long lead-up to this first test,” Polk said in JPL’s announcement. “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.”
NASA Administrator Jared Isaacman framed the result more broadly. “At NASA, we work on many things at once, and we haven’t lost sight of Mars,” Isaacman said, as Gizmodo reported. SpaceWar quoted Isaacman as saying, “This marks the first time in the United States that an electric propulsion system has operated at power levels this high, reaching up to 120 kilowatts.”
The MPD thruster program is led by JPL in collaboration with Princeton University in New Jersey and NASA’s Glenn Research Center in Cleveland, JPL said. SpaceWar reported that the program has been in development for approximately two and a half years. The work is funded by NASA’s Space Nuclear Propulsion project, Gizmodo reported, with the aim of supporting a megawatt-class nuclear electric propulsion program for a future crewed mission to Mars.
Why Lithium and Why MPD
Electric propulsion is more efficient than chemical propulsion but produces far less thrust. Gizmodo noted that electric propulsion uses up to 90% less propellant than traditional, high-thrust chemical rockets. To make a crewed Mars trip practical, NASA wants engines that can run for very long periods at much higher power than today’s flight hardware. ScienceDaily reported that a crewed mission to Mars could require between 2 and 4 megawatts of total power, with multiple thrusters needed.
The MPD architecture uses strong electrical currents and magnetic fields to accelerate plasma made from lithium, as ScienceDaily described, producing greater thrust at higher power levels. The CoMeT chamber exists precisely because metal-vapor propellants are difficult to test safely; ordinary vacuum chambers are not built to absorb condensing lithium. Gizmodo described the chamber as a 26-foot-long water-cooled vacuum chamber at JPL’s Electric Propulsion Lab.
What’s Next
The team’s near-term goal is to reach power levels between 500 kilowatts and 1 megawatt per thruster in the coming years, JPL said. Gizmodo reported that a Mars-bound mission would require multiple such thrusters operating for more than 23,000 hours.
Once fully developed and paired with a nuclear power source, Gizmodo wrote, the MPD could help reduce launch mass to support larger payloads for human Mars missions — the reason the program sits under NASA’s Space Nuclear Propulsion office rather than its solar-electric propulsion line.
What We Don’t Know
The public materials do not disclose specific impulse figures, mass, or efficiency numbers for the Feb. 24 firing, leaving an external comparison to existing flight-proven electric thrusters incomplete. NASA has not published a target launch date for a crewed Mars mission using the technology, and the published material does not detail how the nuclear power source pairing — a separate, unbuilt piece of hardware — would be integrated with the lithium plasma engine. The 23,000-hour operating requirement implies a durability target the prototype has not yet been tested against; the Feb. 24 result is a power milestone, not an endurance milestone.