MIT's Green Propulsion Dual Mode cubesat will test whether one fuel can handle both high thrust burns and low thrust electric station keeping, freeing mass for instruments and longer missions.
Small satellites have always faced a binary choice in propulsion: chemical thrusters for the high-thrust, short burns needed for orbit insertion or collision avoidance, or electric thrusters for the gentle, long-duration pushes that hold a satellite in position. Running both on a single spacecraft has meant carrying two propellant feeds, two sets of tanks, and the mass and volume penalties that come with doubling a propulsion system on a platform that has neither mass nor volume to spare.
A cubesat mission heading to orbit late this year suggests a different design pattern. The Green Propulsion Dual Mode mission, a NASA flight demo built around hardware from MIT's Space Propulsion Laboratory, uses a single propellant to feed both chemical thrusters and electric (electrospray) thrusters on the same spacecraft, according to Space.com. The architecture, if it works in space the way MIT's ground tests suggest, collapses a tradeoff that has shaped small-sat mission design for two decades.
The propellant at the center of the demo is AF-M315E, a hydroxylammonium nitrate-based fuel developed through U.S. Air Force research as a less-toxic alternative to hydrazine, the long-standing standard for satellite monopropellant thrusters. MIT's lab chose AF-M315E because the same fluid can be ignited catalytically for impulsive chemical burns and ionized and accelerated through an electrospray emitter for low-thrust electric thrust, as Space.com reports. A satellite no longer has to choose between two propulsion systems or carry two separate propellant loads to do both kinds of work.
That matters for the missions that have become routine in low Earth orbit. Smallsats used for Earth observation, constellation maintenance, and in-orbit inspection need to perform impulsive maneuvers and stay precisely positioned for months at a time. Today they often do that with cold-gas thrusters, which are simple but inefficient, or with hybrid architectures that pair a chemical system for big burns with a separate electric system for station-keeping. Each subsystem eats into the mass and volume budget a small satellite could otherwise spend on instruments, antennas, or longer-duration hardware. Doubling up on propulsion also means doubling the propellant budgets, which is the binding constraint on what a cubesat can carry into orbit at all.
The Green Propulsion Dual Mode design, often shortened to GPDM, replaces that pair of subsystems with one. The MIT team has delivered four flight-unit electrospray thrusters to NASA in preparation for the cubesat demo, Space.com reported. The work was led by Amelia Bruno, a former postdoctoral researcher at MIT, and was partially funded by NASA. The flight test is also a check on AF-M315E itself, which has been characterized extensively on the ground but has only a small number of in-space heritage missions to its name.
The demo is not a product launch. It is an in-space validation of a design pattern that has been ground-tested in the lab. The cubesat was originally slated to fly in October 2025 and has slipped to no earlier than November, a schedule shift that is itself a useful data point: small-sat missions are still waiting on launch capacity and final integration milestones, and GPDM is no exception. Readers should treat the upcoming flight as a test, not as a deployment.
What to watch next is whether the demo clears two thresholds. The first is performance: the in-space electrospray thrusters need to fire reliably through repeated station-keeping cycles without the catalyst bed or emitters degrading in ways the ground tests could not capture. The second is the second-order effect on small-sat mission planning. If a single propellant can credibly do both jobs, the next question is which mission classes start to treat that capability as a default assumption rather than an exotic option, and which incumbents in the small-sat propulsion market, from cold-gas thruster vendors to Hall-effect electric thruster makers, have to rethink their own roadmaps in response.