Falcon 9
SpaceX's workhorse rocket. SpaceX calls it the world's first orbital-class reusable rocket: its first stage lands on a ship at sea or a landing pad and flies again.
Why it matters
Falcon 9 launches SpaceX's own Starlink satellites, Dragon crew and cargo flights to the space station, national security missions and commercial satellites. Landing and reflying first stages, first done in 2015 and 2017, is now a routine part of its flights.
How the technology works
A two-stage rocket burning rocket-grade kerosene and liquid oxygen. Nine Merlin engines power the first stage, which separates, uses its engines to turn around and slow down, and touches down on four legs on a drone ship or a landing zone.
A single Merlin Vacuum engine on the second stage, which can restart several times, carries the payload to orbit. SpaceX recovers the nose fairing for reuse.