The Dual-Mode Propulsion Breakthrough
Space exploration has long been constrained by a simple, frustrating math problem: mass. To travel deep into the solar system, a spacecraft needs the raw, high-thrust power of chemical propulsion to navigate complex maneuvers, yet it also requires the extreme fuel efficiency of electrical thrusters to survive the long, slow trek across the void. Historically, carrying both systems meant doubling the weight of the fuel tanks, a luxury that briefcase-sized CubeSats simply cannot afford.
Researchers at MIT have effectively solved this engineering bottleneck by creating a system that runs both thruster types on a single, shared propellant. The discovery centers on the use of ASCENT, a green, low-toxicity monopropellant originally developed by the U.S. Air Force for chemical rockets, as reported by Gizmodo. By adapting this salt-based liquid to also feed electrospray thrusters—which rely on electric fields to accelerate charged particles—the team has created a hybrid platform that functions with significantly less mass.
“If you can have chemical and electrical propulsion in one small package, it’s the best of both worlds,” Amelia Bruno, a former postdoc in MIT’s Department of Aeronautics and Astronautics, said in a statement.
How the Hybrid Thruster Functions
The mechanics of this system rely on the versatility of the propellant. In chemical mode, the system converts energy stored in the chemical bonds of the propellant into hot gas, generating the powerful, short-duration bursts necessary for rapid orbital changes. In contrast, the electrospray thrusters operate on a much smaller scale, using dime-sized rockets to emit a fine, efficient spray of charged particles. According to Tomorrow’s World Today, the team validated the design by placing a thruster inside a vacuum chamber that mimics the environment of space, confirming that the propellant successfully generated the necessary spray to rotate the satellite.
This integration creates a new class of mission capability. A satellite equipped with this technology could use the electrical mode for the months-long cruise toward a target like an asteroid, then switch to the chemical mode to perform high-speed corrections or reach specific orbital vantage points.
“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.
Expanding the Reach of CubeSats
The implications for deep-space science are substantial. By reducing the weight and complexity of propulsion, the MIT design lowers the barrier to entry for planetary exploration. Paulo Lozano, a professor of aeronautics and astronautics at MIT and co-author of the study, noted that the flexibility provided by this dual-mode system changes the fundamental mission profile for small spacecraft.
“We could send CubeSats to Mars, or the asteroid belt, where they could make the journey slowly, using electrospray thrusters,” Paulo Lozano, a professor of aeronautics and astronautics at MIT and co-author of the study, said in a statement. “You could then use your chemical thrusters to quickly move to look at interesting features. You could have a lot more flexibility to do a lot more things.”
As Interesting Engineering highlights, the current era of space exploration is defined by the tension between increasingly ambitious scientific goals and the harsh physical constraints of orbital mechanics. Missions must be designed to survive radiation and extreme temperatures without the possibility of repair. By simplifying the propulsion architecture, the MIT team is addressing the practical reality of space flight: the need for systems that deliver long-term reliability while maximizing the limited volume available on small satellite platforms.
Future Mission Outlook
The collaboration with NASA on the “Green Propulsion Dual Mode” mission represents a critical step in moving this technology from the lab to the vacuum of space. While current orbital activity is marked by a surge in commercial operators and a crowded low-Earth orbit, this engine design is specifically aimed at the frontier beyond.
By enabling CubeSats to maintain precise control throughout an interplanetary journey, the researchers are effectively transforming these tiny, low-cost satellites from simple observers into active, agile explorers. The next phase of development will focus on the flight-testing of the integrated four-thruster array, a milestone that could finalize the feasibility of briefcase-sized units for missions that previously required much larger, more expensive hardware. The project suggests a future where the cost of deep-space research is determined more by the ingenuity of the propulsion design than by the sheer weight of the fuel carried on launch.
