Falcon 1 became the first privately developed liquid-fueled rocket to reach orbit.
Its successful fourth flight launched from Omelek Island in the Pacific Ocean on 28 September 2008. Falcon 1 carried a mass simulator and demonstrated that SpaceX could build and operate an orbital launch vehicle after three earlier failures.
The rocket used liquid oxygen and RP-1 kerosene propellants. Its first stage was powered by a Merlin engine, while the second stage used a Kestrel engine. Falcon 1 was small compared with Falcon 9, but its development provided the engineering foundation for SpaceX’s later vehicles.
The distinction matters because privately built solid-fuel rockets and government-developed liquid-fueled launchers existed earlier. Falcon 1’s achievement specifically combined private development, liquid propulsion and successful orbital insertion. SpaceX retired the vehicle after five launches, with two successes.