Technological Advancements of Hybrid Rocket Engines for Sustainable and Competitive In-Space Propulsion Applications

Hybrid rocket propulsion systems, utilizing liquid oxidizers in conjunction with solid hydrocarbon fuels, are recognized for their safety, environmental compatibility, operational simplicity, and capacity for precise control over thrust and impulse profiles. Thus, this emerging technology offers a promising alternative for future space propulsion applications. In the last decade, the Utah State University Propulsion Research Laboratory (PRL) has developed hybrid propulsion technologies for a diverse array of space mission applications. This paper summarizes key progress in the PRL’s green-hybrid propulsion research, offers insights for scalable design future strategies, and presents a road map for future applications.

At the PRL, significant advancements in hybrid rocket technology have addressed both performance and sustainability requirements. Among the key technological advances are a patented low-energy arc-ignition system, which ensures reliable and consistent ignition, and a digital throttle control that enables precise and deep throttling. These advancements significantly enhance flexibility in missions requiring orbital transfer, attitude control, and rendezvous operations. These advances enable hybrid propulsion systems to serve as viable competitors to conventional chemical and electric propulsion methods for space applications.

PRL research also focuses on environmental sustainability alongside ignition and throttling improvements. A key objective is to substitute toxic and hazardous hydrazine-based propellants with safer, environmentally friendly options for in-space propulsion. By leveraging modern additive manufacturing methods, PRL research has enabled fast, affordable solid-fuel production by using recycled and bio-based plastics. These advances have optimized fuels, resulting in lowered production costs, minimized environmental impact, and increased motor efficiency. These advanced fuel blends exhibit advantageous regression rates, consistent mechanical strength, and compatibility with current ignition and oxidizer-feed systems. This research shows that sustainable materials can be used in propulsion without compromising performance, enabling hybrid rocket engines to be competitive in this market space.