- First gen: NASA, governments
- Second gen: Lockheed, Boeing, Raytheon, General Dynamics etc. as contractors
- Third gen: SpaceX, Orbital, Virgin Galactic as private companies
- The first gen was NASA and their subcontractors Boeing, Lockheed, Rocketdyne,
and other military contractors.
- The second gen arrived with 'Star Wars' and the need to put lots of
things in orbit, Rotary Rocket, the DC-X, and a host of other
Single-stage-to-orbit companies.
- The third stage is SpaceX, Virgin Galactic, Blue Origin, Armadillo, Etc.
