Inside a water-cooled vacuum chamber 26 feet (8 meters) long, a nozzle-shaped electrode glowed red and the tungsten rod at its center burned white. Engineers at NASA’s Jet Propulsion Laboratory had just lit a lithium-fed thruster, and the people watching knew what they had been building toward for the better part of three years.
The prototype reached up to 120 kilowatts, the highest power any U.S. test of an electric propulsion system has achieved. That is more than 25 times what the electric thrusters on the Psyche mission draw. Psyche launched in 2023 on its way to a metal-rich asteroid.
“Designing and building these thrusters over the last couple of years has been a long lead-up to this first test,” said James Polk, a senior research scientist at JPL. “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.”
What it is
The device is a lithium-fed magnetoplasmadynamic (MPD) thruster. Large currents interact with a magnetic field and drive lithium plasma out the back. Most electric engines flying now use solar power to push propellant, building speed slowly through a gentle, continuous thrust. This one runs on lithium metal vapor instead.
NASA says electric propulsion in general needs up to 90% less propellant than high-thrust chemical rockets. Lithium thrusters, according to the agency, could run at high power while using propellant efficiently and delivering more thrust power than current electric designs. Paired with a nuclear power source, a mature MPD might trim launch mass and let human Mars missions carry bigger payloads.
The test included five ignitions. Temperatures climbed past 5,000 degrees Fahrenheit (2,800 degrees Celsius).
The distance still to go
JPL has spent two and a half years on the thruster with Princeton University and NASA’s Glenn Research. Funding comes from NASA’s Space Nuclear Propulsion project, which aims to support a megawatt-class nuclear electric propulsion program for a human mission to Mars.
NASA Administrator Jared Isaacman said in a statement: “At NASA, we work on many things at once, and we haven’t lost sight of Mars.” He called the result real progress toward putting an American astronaut on the Red Planet.
The gap between the lab and a spacecraft is wide. A crewed ship bound for Mars might need 2 to 4 megawatts, which would take several MPD thrusters running for more than 23,000 hours. The team is aiming for 500 kilowatts to 1 megawatt per thruster in the coming years, and the data from this first firing will shape the next round of tests. Heat is the stubborn problem. Engineers have to show the components can survive it for hours at a time.
Sources
Sources
- NASA's Lithium-Fed Nuclear Thruster Flares to Life in First of Its Kind…
- Google News – NASA tests 120-kilowatt lithium thruster for Mars…
