Descent Propulsion System

The Descent Propulsion System (DPS) or LMDE (Lunar Module Descent Engine) is a variable throttle hypergolic rocket engine developed by Space Technology Laboratories (TRW) for use in the Apollo Lunar Module Descent Stage. It used Aerozine 50 fuel and N₂O₄ oxidizer. This engine used a pintle injector, a design also used later in the SpaceX Merlin engine.