The RL10 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. Originally designed in the 1950s, the RL10 has undergone multiple upgrades and improvements over the years. It is capable of producing around 22,000 pounds of thrust and has been instrumental in launching payloads into orbit, contributing to missions by organizations like NASA and United Launch Alliance.