The RL10A is a rocket engine developed by Aerojet Rocketdyne that uses liquid hydrogen and liquid oxygen as propellants. It is known for its high efficiency and reliability, making it suitable for upper-stage propulsion in various space missions. The engine has been used in several launch vehicles, including the Centaur upper stage. This engine is part of the RL10 family, which has a long history of successful flights since its first use in the 1960s. The RL10A variant features a simple design and is capable of multiple ignitions, allowing it to perform complex maneuvers in space.