The RL10B is a rocket engine developed by Aerojet Rocketdyne, primarily used in upper-stage propulsion for various launch vehicles. It operates on liquid hydrogen and liquid oxygen, providing high efficiency and performance for missions that require precise orbital insertion. This engine is an evolution of the original RL10 design, featuring improvements in reliability and thrust. The RL10B has been utilized in notable launch systems, including the Centaur upper stage, and plays a crucial role in delivering payloads to space, such as satellites and interplanetary missions.