Monopropellanta

Monopropellant is a type of rocket propellant that consists of a single chemical compound. Unlike bipropellants, which require two separate components (fuel and oxidizer) to combust, monopropellants contain both fuel and oxidizer within the same molecule or mixture. When passed over a catalyst or exposed to a high-temperature source, the monopropellant decomposes exothermically, producing hot gas that is expelled through a nozzle to generate thrust.

The primary advantage of monopropellants is their simplicity. They require less complex plumbing and fewer storage tanks compared to bipropellant systems, leading to lighter and more compact rocket engines. This makes them well-suited for applications where simplicity, reliability, and ease of operation are paramount, such as in spacecraft attitude control thrusters, small satellite propulsion, and auxiliary propulsion systems.

Common examples of monopropellants include hydrazine (N2H4) and hydrogen peroxide (H2O2). Hydrazine, in particular, has been widely used due to its high performance and stable nature. However, monopropellants generally have lower specific impulse (a measure of propellant efficiency) compared to bipropellants, meaning they produce less thrust for a given amount of propellant. This makes them less suitable for primary propulsion systems on larger rockets or spacecraft requiring high-energy maneuvers. The decomposition of monopropellants can also be highly energetic and requires careful handling and storage.