MIT engineers are developing a dual-mode propulsion system that allows small satellites to use a single fuel source for both high-thrust chemical maneuvers and high-efficiency electric propulsion. By utilizing the U.S. Air Force’s ASCENT propellant, researchers aim to replace the need for separate fuel systems, potentially enabling CubeSats to conduct complex deep-space missions that were previously restricted by weight and volume constraints.
How Dual-Mode Propulsion Works
Traditional satellite design requires separate tanks and hardware for chemical thrusters—used for rapid orbital changes—and electric thrusters, which provide fuel-efficient, long-duration propulsion. MIT’s approach, led by researchers in the Department of Aeronautics and Astronautics, consolidates these functions. According to a study published in the Journal of Propulsion and Power, the team successfully utilized Advanced SpaceCraft Energetic Non-Toxic (ASCENT) propellant to power both chemical and electrospray thruster systems. Electrospray thrusters use electric fields to accelerate ions from a liquid, providing precise, low-force movement suitable for long-distance interplanetary travel. By using one propellant for both, engineers can reduce the mass and mechanical complexity of small satellite buses.
The Role of ASCENT Propellant
The U.S. Air Force developed ASCENT as a safer, more stable alternative to hydrazine, a highly toxic chemical traditionally used in spacecraft propulsion. As an ionic liquid, ASCENT remains stable in the vacuum of space, which is critical for electrospray thruster performance.
"ASCENT happens to be an ionic liquid mixture," said Amelia Bruno, lead author of the study and former MIT AeroAstro postdoc. "Theoretically, this should work. Let’s go figure out how."
Laboratory testing conducted by Bruno, Paulo Lozano, and Matthew Corrado confirmed that ASCENT performs at levels comparable to conventional ionic liquid fuels in electrospray systems. During 100-hour continuous operation tests inside a vacuum chamber, the thrusters successfully generated the necessary thrust to maneuver a test platform, verifying that the fuel is compatible with miniaturized hardware.
Upcoming NASA Mission Milestones
The technology is scheduled for its first orbital demonstration via NASA’s Green Propulsion Dual Mode mission. This mission will deploy a CubeSat equipped with a single shared propellant tank feeding both chemical and electric thrusters.
According to Paulo Lozano, the Miguel Alemán Velasco Professor of Aeronautics and Astronautics at MIT, this flight represents a significant shift in small satellite capabilities. If the mission succeeds, it will demonstrate that CubeSats can perform deep-space exploration to locations like Mars or the asteroid belt while maintaining the agility to perform high-speed observations upon arrival.
Comparison of Propulsion Capabilities
| Feature | Chemical Thrusters | Electrospray Thrusters |
|---|---|---|
| Primary Use | Rapid acceleration/maneuvering | Long-duration, precise travel |
| Thrust Level | High | Very Low |
| Efficiency | Lower (Higher fuel consumption) | High (Lower fuel consumption) |
| Propellant Type | ASCENT (Dual-mode compatible) | ASCENT (Dual-mode compatible) |
Future Implications for Satellite Constellations
Beyond deep-space exploration, this dual-mode capability offers practical benefits for Earth-orbiting satellite constellations. Operators tasked with climate or weather monitoring often struggle to position assets quickly when dynamic events, such as developing storms, occur. With dual-mode propulsion, a satellite could use its chemical system to reach a specific area rapidly and then rely on its electric system for precise station-keeping. This research, supported in part by NASA, provides a pathway for smaller, more affordable platforms to perform mission profiles previously reserved for large, expensive spacecraft.
