The United States is developing a restartable solid‑fuel engine for rockets to simplify and increase the reliability of satellites.

New Approach to Solid‑Fuel Rockets: Restartability and Thrust Regulation

Traditional solid‑fuel engines operate only once—from launch until the propellant is completely burned. For multiple launches and maneuvering, complex, expensive liquid systems are required. In the United States, people are considering how to make space more accessible if a solid‑fuel engine could be turned on, off, and throttled by command.

Who’s working on the solution?

The collaboration involves specialists from Aerospace Corporation, the University of Southern California (USC), and the Naval Postgraduate School (NPS). Their goal is to create a restartable solid‑fuel engine with plasma control.

How will it work?

The idea is based on nanosecond pulsed plasma discharge (NPPD). Inside the engine, ultra‑short high‑voltage pulses (< 100 ns) generate low‑temperature plasma. This plasma can enhance or initiate combustion, and most importantly allows electronic control of the process: turning it on, off, and throttling thrust.

New Materials for Propellant

The team is also developing “ion‑liquid” polymers—a blend of heat‑resistant ionic liquids with the strength of conventional polymer. This propellant remains stable over a wide temperature range while being electrochemically active, which is crucial for plasma control.

Practical Value of the Project

The result is a compact, simple, and potentially safer engine suitable for both satellites and interplanetary vehicles. It doesn’t require complex fuel pumping systems or high‑pressure tanks but enables multiple maneuvers, orbit corrections, and mission extension.

Researchers are even considering mounting such engines on CubeSats—small satellites that typically can’t afford expensive liquid systems. This opens new opportunities for small companies and academic institutions aiming for space projects without large financial outlays.