Propellant utilization efficiency

Propellant utilization efficiency refers to how effectively a rocket engine converts its stored propellant into useful thrust. It measures the percentage of this propellant that actively contributes to pushing the spacecraft forward, rather than being lost as unused exhaust. Higher efficiency means more of the propellant's energy is used to generate movement, which can extend the spacecraft’s mission duration or reduce fuel costs. Essentially, it reflects how well the engine maximizes the value of the propellant from launch to arrival at the destination.