Merlin is a family of rocket engines developed by Space Exploration Technologies Corporation, doing business as SpaceX. They are currently a part of the Falcon 9 Block 5 partially reusable two-stage-to-orbit, medium-lift launch vehicle and Falcon Heavy super heavy-lift launch vehicle, and were formerly used on the Falcon 1 two-stage small-lift launch vehicle. Merlin rocket engines use RP-1 and LOX as rocket propellants in a gas-generator power cycle. The Merlin engine was originally designed for sea recovery and reuse, but since 2016 the entire Falcon 9 booster is recovered for reuse by landing vertically on a landing pad using one of its nine Merlin 1D engines.
