The Falcon 9 v1.1, which first flew in September 2013, stretched both stages of the vehicle, introduced Merlin-1D engines in place of the earlier Merlin-1Cs, and rearranged the first stage engines ...

Falcon 9’s second stage is also powered by a Merlin-1D engine, which is optimized for operation in the vacuum of space. This Merlin Vacuum (MVac) engine ignited one second after stage separation ...

SpaceX on Wednesday night launched a Spanish communications satellite from the Kennedy Space Center in Florida and retired the first-stage booster rather than landing on a drone.