NASA Ignites Prototype Thruster Designed to Put Humans on Mars

by Aaron Leong — Wednesday, April 29, 2026, 10:26 AM EDT

NASA has tested a lithium-fed thruster that could become a workhorse for future Mars missions, and the key milestone is not just that it fired, but that it did so at power levels no previous electric thruster test in the United States ever reached. The experiment is a small but meaningful step toward nuclear electric propulsion, a system NASA says could move heavy cargo and eventually crews more efficiently across deep space.

On February 24 at the Jet Propulsion Laboratory in Southern California, engineers ignited a prototype lithium-fed magnetoplasmadynamic, or MPD, thruster inside a specialized vacuum chamber built for metal-vapor propulsion tests. The device reached up to 120 kilowatts, which NASA says is more than 25 times the power of the highest-power electric thrusters now flying on any NASA spacecraft. In all five firings, the central electrode glowed above 5,000°F (2,800°C).

What makes the test important is not only the power level but the efficiency the system could eventually deliver. MPD thrusters use strong electric currents and magnetic fields to accelerate lithium plasma, a design NASA has championed since the 1960s but never flown operationally. Compared with current electric propulsion systems, the promise is higher thrust at high power and better propellant efficiency, two qualities that matter when the goal is to move massive spacecraft rather than tiny probes.

mpd comet — *The prototype thruster is enclosed in JPL’s condensable metal propellant (CoMeT) vacuum facility (Credit: NASA/JPL-Caltech)*

NASA says a manned Mars mission could require 2 to 4 megawatts of power, which would mean multiple thrusters operating for more than 23,000 hours. That is a punishing durability problem, and it explains why the recent firing is only the opening chapter of a much longer test campaign. The team now aims to push individual thrusters toward 500 kilowatts and eventually 1 megawatt, while test-proving the hardware to survive heat and stress of thousands of hours of operation.

The work is led by JPL in partnership with Princeton University and NASA’s Glenn Research Center, under the latter's Space Nuclear Propulsion project. Based at Marshall Space Flight Center, the program has spent years laying groundwork for megawatt-class nuclear electric propulsion, which would pair advanced thrusters with a compact nuclear power source. In practical terms, that combo could reduce launch mass, free up payload capacity, and make crewed Mars travel less constrained by the limits of chemical rockets.

Of course, there's still a gulf between a promising test and a flight-ready engine, but the result shows that a once-theoretical propulsion concept has moved into the realm of serious engineering.

Main photo: JPL senior research scientist James Polk peers into the CoMeT vacuum facility at JPL’s Electric Propulsion Lab (Credit: NASA/JPL-Caltech)