MIT Engineers Develop Revolutionary Spacecraft Engine Combining Chemical and Electric Propulsion

MIT researchers have developed a groundbreaking spacecraft propulsion system that combines the rapid thrust of chemical rockets with the fuel efficiency of electric thrusters, using a single propellant for both functions. The innovation could dramatically expand the capabilities of small satellites, allowing them to perform both quick maneuvers and long-duration missions without the weight and complexity of separate fuel systems. A NASA-supported CubeSat mission will soon test this dual-mode technology in orbit.

The breakthrough centers on a specialized "green monopropellant" originally developed by the U.S. Air Force for chemical propulsion that can also power miniature electric thrusters called electrospray thrusters. Lead author Amelia Bruno, a former postdoc in MIT's Department of Aeronautics and Astronautics, explained that this represents the best of both worlds for spacecraft design. "If you can have chemical and electrical propulsion in one small package, it's the best of both worlds," Bruno said. "This opens the door for small satellites to do even more science, more observations, and more interesting missions, all on a smaller and cheaper platform."

Electrospray thrusters, roughly the size of a dime, use electric fields to charge particles in liquid propellant and eject them into space for thrust. While extremely fuel-efficient and well-suited for precise, gradual maneuvers over long distances, they cannot provide the powerful bursts needed for rapid acceleration or major orbital changes. Chemical thrusters fill this gap by delivering high-power propulsion, but they consume fuel much more quickly and are designed for short, intense operations rather than sustained flight.

The MIT team is currently working with NASA on the Green Propulsion Dual Mode mission, featuring a briefcase-sized CubeSat equipped with one chemical thruster and four electrospray thrusters, all drawing from a single fuel tank. If successful, the technology could enable small satellites to venture far beyond Earth orbit on interplanetary missions. "We could send CubeSats to Mars, or the asteroid belt, where they could make the journey slowly, using electrospray thrusters," said study co-author Paulo Lozano, the Miguel Alemán Velasco Professor of Aeronautics and Astronautics at MIT. "You could then use your chemical thrusters to quickly move to look at interesting features."

The implications extend beyond scientific missions to commercial satellite operations and space exploration. Traditional spacecraft require separate propellant systems for different types of maneuvers, adding significant weight, cost, and complexity. By eliminating this constraint, the dual-mode system could make sophisticated space missions accessible to smaller organizations and enable new types of scientific investigations. The technology could also prove valuable for larger spacecraft, providing greater operational flexibility while reducing the logistical challenges of managing multiple fuel systems in the harsh environment of space.